manualshive.com logo in svg

Keithley 2701, Руководство пользователя

Поделиться
Скачать
Keithley 2701 Скачать руководство пользователя страница 58

Model 2701 User’s Manual

Close/Open Switching Module Channels

2-3

NOTE

The Model 2701 can scan switching module channels. Each channel in the scan 
can have its own unique setup configuration. Scanning is covered in Section 7. 

NOTE

When a setup is saved as a user setup (SAV0, SAV1, SAV2, SAV3, or SAV4), 
closed channels are also saved. When the setup is restored, those channels (and 
only those channels) will be closed (see “Defaults and user setups,” page 1-21).

2701-900-01.book  Page 3  Wednesday, August 3, 2011  9:43 AM

Содержание 2701

Страница 1: ...P2701 900 01G 2701 900 01G A Greater Measure of Confidence www tek com keithley Model 2701 Ethernet Based DMM Data Acquisition System User s Manual 2701 900 01 Rev G February 2016...

Страница 2: ...sed DMM Data Acquisition System User s Manual 2002 2016 Keithley Instruments All rights reserved Cleveland Ohio U S A Document Number 2701 900 01 Rev F February 2016 2701 900 01 book Page 1 Wednesday...

Страница 3: ...uld be performed only by service personnel Service personnel are trained to work on live circuits perform safe installations and repair products Only properly trained service personnel may perform ins...

Страница 4: ...surface capable of withstanding the voltage being measured The instrument and accessories must be used in accordance with its specifications and operating instructions or the safety of the equipment m...

Страница 5: ...ther components that are not safety related may be purchased from other suppliers as long as they are equivalent to the original component note that selected parts should be purchased only through Kei...

Страница 6: ...ower up sequence 1 17 Keyclick 1 19 Display 1 19 Status and error messages 1 19 Remote programming display 1 19 Defaults and user setups 1 21 Saving and restoring setups 1 21 Remote programming defaul...

Страница 7: ...switching module 2 36 Switching module capabilities 2 36 Schematic diagram 2 37 3 Basic DMM Operation 3 1 DMM measurement capabilities 3 2 High energy circuit safety precautions 3 3 Performance consid...

Страница 8: ...sic measurements 3 51 Basic measurement commands 3 51 Basic measurement programming examples 3 57 Measurement queries 3 58 FETCh 3 58 READ 3 59 MEASure function 3 60 SENSe 1 DATA FRESh 3 60 SENSe 1 DA...

Страница 9: ...alling readings 6 6 Buffer statistics 6 7 Remote programming buffer 6 8 Buffer commands 6 8 Programming example 6 15 7 Scanning 7 1 Scanning fundamentals 7 2 Channel assignments 7 3 Sequential and non...

Страница 10: ...ith BNC connections 8 14 Remote programming triggering 8 16 Trigger model remote operation 8 16 Trigger model operation 8 18 Triggering commands 8 19 Programming example 8 20 9 Limits and Digital I O...

Страница 11: ...words 10 21 Query commands 10 23 Case sensitivity 10 23 Long form and short form versions 10 23 Short form rules 10 24 Program messages 10 24 Response messages 10 27 Message exchange protocol 10 27 RS...

Страница 12: ...4 SYSTem PRESet 14 4 SYSTem VERSion 14 4 SYSTem KEY NRf 14 4 SYSTem BEEPer STATe b 14 5 15 SCPI Reference Tables 15 1 Reference tables 15 2 Model 2701 Ethernet Data Acquisition System A 2 Model 7700...

Страница 13: ...TCh D 10 READ D 10 MEASure D 10 CALC 1 DATA LATest D 10 CALC 1 DATA FRESh D 10 CALC3 LIM1 FAIL D 11 CALC3 LIM2 FAIL D 11 TRACe DATA D 11 CALC2 IMM D 12 CALC2 IMM D 12 CALC2 DATA D 12 Continuous measur...

Страница 14: ...Model 2701 Ethernet Based DMM Data Acquisition System Table of Contents ix Visual Basic and CVI C examples G 2 LabVIEW examples G 12 2701 900 01 book Page ix Wednesday August 3 2011 9 43 AM...

Страница 15: ...dules Summarizes the capabilities of the Keithley Model 77xx series switching modules QS1 Front and rear panel familiarization Summarizes the controls and connectors of the instrument Rack mounting Co...

Страница 16: ...contact with these voltages The WARNING heading used in this manual explains dangers that might result in personal injury or death Always read the associated information very carefully before performi...

Страница 17: ...ories Plug inswitchingmodules NOTE Table 1 1 provides a side by side comparison of the following Keithley switchinging modules All multiplexer modules can be configured as two independent multiplexers...

Страница 18: ...single pole dual 1 4 RF Multiplexer module eight channels no measurement capability This 1 4 multiplexer is a cascad ing tree design one of the channels of each is always connected to a common out It...

Страница 19: ...igger cable Lets you connect trigger link lines one Volt meter Complete and one External Trigger of Model 2701 to instruments that use BNC trigger connectors Model 8503 is one meter long Model 7009 5...

Страница 20: ...Setup storage Seven instrument setups five user RST defaults and factory defaults can be saved and recalled Offset compensated ohms A two measurement process for 4 wire ohms to cancel the effects of...

Страница 21: ...2701 This feature allows you to configure your system without having the actual switching module installed in the unit There is a pseudocard for every Keithley Model 77xx series switching module For...

Страница 22: ...Unique features All DMM functions All DMM functions except amps All DMM functions All DMM functions except amps Model 7705 Model 7706 Model 7707 Model 7708 2 pole Operation N A 20 channels 10 channels...

Страница 23: ...r type 1 female DB 50 1 female DB 25 3 5mm removable screw terminals 10 SMA Configuration2 6 x 8 matrix Multiplexer Multiplexer Unique features Rows 1 2 connect to DMM system channel operation High sp...

Страница 24: ...on and operation keys Top Row Unshifted DCV Selects DC voltage measurement function ACV Selects AC voltage measurement function DCI Selects DC current measurement function ACI Selects AC current measu...

Страница 25: ...able disables monitor channel CH OFF Disables channel for a scan must be in scan channel setup mode CARD Identifies switching modules installed in mainframe Set up switching modules that require confi...

Страница 26: ...ading has reached or exceeded the enabled high limit HOLD 2701 in hold mode LOW Reading has reached or exceeded the enabled low limit MATH mX b percent or reciprocal 1 X calculation enabled MED Medium...

Страница 27: ...rear panel of Model 2701 is shown in Figure 1 2 As shown a slot cover is installed on slot 2 Figure 1 2 Model 2701 rear panel 5 6 1 2 3 4 KEITHLEY SLOT COVER TRIGGER LINK ETHERNET 10 100 BaseT Link Ac...

Страница 28: ...ection 10 Ethernet connections 4 RS 232 Female DB 9 connector for RS 232 operation Use a straight through not null modem DB 9 shielded cable 5 Power module Contains the AC line receptacle power line f...

Страница 29: ...rrect line voltage may cause dam age to the instrument possibly voiding the warranty 2 Before plugging in the power cord make sure that the front panel power switch is in the off O position 3 Connect...

Страница 30: ...ed from the AC line and other equipment before changing the line voltage setting or replacing the line fuse 1 Place the tip of a flat blade screwdriver into the power module by the fuse holder assembl...

Страница 31: ...shing it in until it locks in place Power up sequence NOTE If a problem develops while the instrument is under warranty return it to Keithley Instruments for repair A short description of any displaye...

Страница 32: ...talled in both slots the following messages will be displayed 1 7700 2 7700 If a slot is empty the message NONE will be displayed instead If the saved power on setup is not the factory defaults setup...

Страница 33: ...1 10 for a complete listing of display annunciators NOTE The display test allows you to test display digit segments and annunciators The key test checks the functionality of front panel keys These tes...

Страница 34: ...e message and disables the text message mode DISPlay ENABle ON OFF Control display circuitry This command is used to enable and disable the front panel display circuitry When dis abled the instrument...

Страница 35: ...set the instrument The RST command returns the instrument to the RST defaults and for the most part the SYSTem PRESet command returns the instrument to the factory default conditions The exceptions ar...

Страница 36: ...asetup 1 Press SHIFT and then SETUP to access the restore setup menu 2 Press to place the cursor on the present RESTORE setup FACT RST SAV0 SAV1 SAV2 SAV3 or SAV4 3 Use the or key to display the desir...

Страница 37: ...ast 0 01 PLC Fast 0 01 PLC Threshold level 10 10 Current AC and DC Bandwidth AC 30 30 Digits AC 5 digits 5 digits Digits DC 6 digits 6 digits Filter On Off Window 0 1 0 1 Count 10 10 Type Moving Repea...

Страница 38: ...Off Reference 1 0 1 0 1 X Reciprocal Off Off Monitor Off Off Output Beeper Never Never Digital Output Off Off Logic Sense High High Pulse No off No off Ratio Off Off Resistance 2 and 4 Digits 6 digit...

Страница 39: ...effect No effect Advanced scan Setup No effect No effect Immediate trigger On On Limit triggers Off Off Timer Off Off Reading count No effect No effect Temperature Digits 5 digits 5 digits Filter On O...

Страница 40: ...its AC 5 digits 5 digits Digits DC 6 digits 6 digits Filter On Off Window 0 1 0 1 Count 10 10 Type Moving Repeat Range Auto Auto Rate DC Slow 5 PLC Slow 5 PLC Rel Off Off Note With a Model 7700 7706 o...

Страница 41: ...hey exclude most optional command words and query commands Optional command words and query commands are summarized as follows Optional command words In order to be in conformance with the IEEE 488 2...

Страница 42: ...e readings See Internal web page in Section 10 for details WARNING For the exercises it is not necessary to connect an input signal or DUT to the instrument front panel inputs or switching module inpu...

Страница 43: ...s measurement mode Most of the other settings for factory and RST defaults are the same For remote programming the following command is used to select function NOTE Items in brackets are optional and...

Страница 44: ...ngs Press EXIT to exit recall mode CALC1 DATA 1 To avoid problems with remote programming it is good practice to routinely clear the buffer TRAC CLE at the begin ning of a program that performs multip...

Страница 45: ...unction the resistance DUT would be connected to DMM Input as shown Figure 1 4 For a 4 wire function i e 4 a channel pair is connected to the DMM when a system channel is closed The system channel is...

Страница 46: ...displayed on the Model 2701 The slot number for the module is also displayed For example 103 indicates that system input channel 3 for a module in slot 1 is closed The paired channel for a 4 wire func...

Страница 47: ...el 3 for a module in slot 1 the following command would be sent ROUTe CLOSe 103 2 Only the closed system channel is returned by ROUTe CLOSe The paired channel for a 4 wire function is not returned For...

Страница 48: ...stem channel 101 Press the key Channel 1 connects to DMM Input see Figure 1 4 ROUT CLOS 101 4 Close system channel 102 Press the key Channel 2 connects to DMM Input ROUT CLOS 102 5 Close system channe...

Страница 49: ...umber of scans to perform and is best explained by an example Assume there are 10 channels in the scan list i e 101 through 110 If you set the reading count to 10 or less one scan of the 10 channels w...

Страница 50: ...y SIMPLE option and press ENTER Specify minimum channel XXX and press ENTER SHIFT SCAN STE CONFIG Press SHIFT Press CONFIG STEP MAX CHAN YYY Specify maximum channel YYY and press ENTER TIMER NO YES Di...

Страница 51: ...ONFIG select INT SIMPLE set MIN CHAN101 set MAX CHAN 108 select TIMER NO set RDG CT 000008 ROUT SCAN 101 108 SAMP COUN 8 4 Enable and start scan2 ROUT SCAN LSEL INT Press STEP INIT 5 Halt disable scan...

Страница 52: ...ercise 6 Return a single reading continuous triggering Details on the commands to trigger and return readings are provided in other sections of this manual For details refer to the following sections...

Страница 53: ...r state Set 2701 to perform one measurement 1 If a MATH function mX B percent or 1 X is enabled the result of the calculation will be returned MATH functions are covered in Section 5 3 FETCh CALC DATA...

Страница 54: ...ffer Statistics for buffer readings are also stored in the buffer CALC2 commands are used to calculate and return buffer statistics see Section 6 for details TRAC CLE Clear buffer1 Trigger and Return...

Страница 55: ...rigger state OR OR Return basic reading2 3 Return result of MATH calculation1 2 1 If a MATH function mX B percent or 1 X is enabled the result of the calculation will be returned If there is no MATH f...

Страница 56: ...operation Provides detailed information for using system channel operation Multiple channel operation Provides detailed information for using multiple channel operation Due to safety considerations th...

Страница 57: ...odule and other equipment Multiple channel operation should only be used by experienced test engineers CAUTION To prevent damage to a switching module do not exceed the maximum signal level input for...

Страница 58: ...have its own unique setup configuration Scanning is covered in Section 7 NOTE When a setup is saved as a user setup SAV0 SAV1 SAV2 SAV3 or SAV4 closed channels are also saved When the setup is restore...

Страница 59: ...nnected to DUT make sure power is removed from all external circuitry Module installation WARNING Slot covers must be installed on unused slots to prevent personal contact with high voltage circuits P...

Страница 60: ...ted to the front panel input the test lead insulation for the switching module must also be rated for 1000V WARNING Dangerous arcs of an explosive nature in a high energy circuit can cause severe pers...

Страница 61: ...docard in slot 1 SYSTem PCARd2 name Install pseudocard in slot 2 name C7700 C7701 C7702 C7703 C7705 C7706 C7707 C7708 C7709 C7710 C7711 or C7712 Programming example The following command sets up the M...

Страница 62: ...ation include the following There can only be one system channel This is the channel that is presently displayed and closed on the Model 2701 When a channel is not displayed there is no system channel...

Страница 63: ...em channel close keys both the Channel 1 relay and the backplane isolation relay Channel 25 close to connect the channel to the DMM The complete simplified schematic of the Model 7700 is provided in F...

Страница 64: ...on such as 4 is selected When channel 101 is closed using the system channel close keys the Channel 1 relay and the input backplane isolation relay Channel 25 closes to connect the channel to DMM Inpu...

Страница 65: ...ve measurement channels For example the Model 7705 switching module does not have any measurement channels Those channels cannot be internally connected to the DMM NOTE The and keys can also be used t...

Страница 66: ...connected to the DMM Trying to close an amps channel while on a non amps function The DCI or ACI function must be selected in order to close an amps channel Trying to close a paired channel while on...

Страница 67: ...y OPEN ALL 2 Press OPEN a second time or press ENTER to open all channels NOTE Opening the system channel disables Ratio or Channel Average Ratio and Channel Average operation are covered in Section 5...

Страница 68: ...including paired channels for 4 wire functions This query command will not return non measurement channels such as backplane isolation channels and the pole mode channel d ROUTe OPEN ALL This command...

Страница 69: ...r channels on the module will open Non ampsswitchingmodules NOTE Presently non amps Keithley modules include the Models 7701 7703 7706 7707 7708 and 7709 You can check the Keithley website www keithle...

Страница 70: ...modules Keep the following in mind when using a non measure module For a non measure card no channels are connected to the internal DMM the channels cannot be connected to the backplane Multiple chan...

Страница 71: ...damage to the switching modules and external circuitry Multiple channel operation should be restricted to experienced test engineers who recognize the dangers associated with multiple channel closures...

Страница 72: ...el operation can result in corrupt measurements For example assume two Model 7700s installed in slots 1 and 2 and a 2 wire function selected If you use multiple channel operation to close channels 201...

Страница 73: ...LOSE key and then use the or key to display the CLOSE MULTI message 2 Press ENTER to display the prompt to close a channel CLOSE MLT XXX 3 Using and key in the three digit channel you want to select 4...

Страница 74: ...OPEN ALL message will be displayed 2 Press the or key to display the OPEN MULTI message 3 Press ENTER to display the prompt to open a channel OPEN MLT XXX 4 Using and key in the three digit channel y...

Страница 75: ...the integrity of the temperature reading will be questionable ERR annunciator on See Temperature measurements page 3 33 for details NOTE OPC or OPC should be used with ROUT MULT CLOS if the clist is...

Страница 76: ...y channel specified in the clist It is valid for both measurement and non measurement channels For example assume channel 125 is closed and you use this command to query channels 101 104 and 125 clist...

Страница 77: ...channel 101 instead of channel 102 1 Use the ALL option for the OPEN key to open all channels in the mainframe Remote programming ROUT OPEN ALL 2 Press the key to close and display channel 101 This cl...

Страница 78: ...1 from channel 111 The Model 2701 will display the 1k reading for system channel 101 Remote programming ROUT CLOS 101 3 Using the MULTI option for the OPEN key open channel 111 This opens the connecti...

Страница 79: ...for details A multiplexer switching module is configured as two multiplexers by using multiple channel operation to close the 2 pole 4 pole relay The Model 7700 is configured as two independent multi...

Страница 80: ...1 Ch 10 Ch 11 Ch 20 Ch 23 Closed Ch 24 Ch 25 Multiplexer A 1x10 Multiplexer B 1x10 For the dual multiplexer configuration Ch 23 must be closed and Ch 24 must remain open HI LO HI LO Channels 2 9 HI L...

Страница 81: ...closed while testing DUT Opening channel 24 isolates the external source from the backplane of the Model 2701 This channel must remain open while testing DUT Closing channel 25 connects an input chann...

Страница 82: ...er application connections Ch 1 DUT 1 H1 LO Ch 2 DUT 2 H1 LO Ch 10 DUT 10 H1 LO Ch 11 H1 LO Ch 12 H1 LO Ch 20 H1 LO Ch 23 Closed Ch 25 Ch 24 H1 LO External Source Model 7700 Switching Module Model 270...

Страница 83: ...asurements with the INTernal or EXTernal reference junction selected The SIMulated reference junction will instead be used resulting in invalid readings The ERR annunciator will turn on to indicate th...

Страница 84: ...anel operation Press CLOSE Select MULTI Key in 101 Press ENTER Press CLOSE Select MULTI Key in 111 Press ENTER Remote programming ROUT MULT CLOS 101 111 4 Measure DUT 1 Front panel operation Take read...

Страница 85: ...nalog outputs for switching modules that have one or more of those capabilities i e Models 7706 and 7707 View the analog input channels that are presently closed Also read digital input ports digital...

Страница 86: ...ilt into a string that scrolls the display Four dots identify the end of the string Model 7700 example Slot 1 Assume the 4 function is selected and system channel 101 is closed The following string wi...

Страница 87: ...commands to acquire general information about the installed modules OPT For remote operation the OPT command can be used to determine which switching modules or pseudocards are installed in the Model...

Страница 88: ...ble voltage Determine if the module supports multiplexer or isolated channels Determine if the module has built in temperature sensors for internal cold junction thermocouple temperature measurements...

Страница 89: ...Table 2 3 Details follow the table NOTE The relay closure count can be reset to zero For details see the Model 2701 Service Manual Plug in module relay closure count Table 2 3 Relay closure count com...

Страница 90: ...t time interval which is initially set to 15 minutes at the factory or whenever the counts are queried Valid intervals set in integer number of minutes are between 10 and 1440 minutes 24 hrs The lower...

Страница 91: ...hannel or channel pair can be closed at the same time When you close a channel or channel pair all other measurement channels will open The user has no control of channels 23 24 and 25 The open close...

Страница 92: ...n a 2 wire function i e DCV is selected channel 23 opens 2 pole position to allow any of the 20 channels to be connected to the input backplane When a 4 wire function is selected channel 23 closes 4 p...

Страница 93: ...Pole Open 4 Pole Closed See Note 3A 3A To Model 2701 Backplane Channel 25 See Note Backplane Isolation Channel 24 See Note Backplane Isolation Channels 23 and 25 in this schematic refer to the design...

Страница 94: ...ements Current measurements DCI and ACI Provides detailed information for making basic DC and AC current measurements Resistance measurements Provides detailed information for making resistance measur...

Страница 95: ...10nA to 3A ACI AC current measurements from 1 A to 3A 2 2 wire resistance measurements from 100 to 120M 4 4 wire resistance measurements from 100 to 120M FREQ Frequency measurements from 3Hz to 500kHz...

Страница 96: ...for hands off measurements Do not use test leads that decrease voltage spacing These diminish arc protection and create a hazardous condition WARNING For the front panel inputs the maximum common mod...

Страница 97: ...calculate the reading of the input signal This process is known as autozeroing When autozero is disabled the offset gain and internal temperature measurements are not performed This increases the meas...

Страница 98: ...the power line cycle If the next trigger Trigger 2 occurs during the negative cycle then the measurement process also starts with the positive going zero crossing Figure 3 1 Line cycle synchronizatio...

Страница 99: ...Description Default Autozero command SYSTem AZERo STATe b Enable or disable autozero b ON or OFF ON Line synchronization command SYSTem LSYNc STATe b Enable or disable LSYNC b ON or OFF OFF After ena...

Страница 100: ...nframe slot number 1 or 2 CH Switching module channel number must be 2 digits Examples 101 Slot 1 Channel 1 101 203 Slot 1 Channel 1 and Slot 2 Channel 3 101 110 Slot 1 Channels 1 through 10 Throughou...

Страница 101: ...gh voltage probe must be terminated to a 10M load The input divider cannot be enabled from the front panel For remote programming the following command controls the input divider VOLT IDIVider b Enabl...

Страница 102: ...100V ranges 10G on 10V 1V and 100mV ranges Caution Maximum Input 1000V peak A DCV Connections B ACV Connections Model 2701 DC Voltage Source Model 2701 AC Voltage Source F 500V PEAK FRONT REAR 3A 250...

Страница 103: ...3C one DC voltage source is connected to a primary channel i e 104 and the other source is connected to its paired channel i e 114 NOTE The ratio and channel average calculations are covered in Secti...

Страница 104: ...WARNING If both the front panel terminals and the switching module terminals are connected at the same time the test leads must be rated to the highest voltage that is connected For example if 1000V i...

Страница 105: ...ed waveform with an average value of zero The reason to consider crest factor in accuracy of RMS measurements is because the meter has a limited bandwidth Theoretically a sine wave can be measured wit...

Страница 106: ...RMS 1 VAVG VAVG VP VRMS VP CF 2 V 0 V AC coupled RMS V VP 1 1 V VP VP D 2 VP 2 VP 2 VRMS D 2 1 2 VP D 2 D 2 CF D 2 1 2 1 VRMS Crest Factor VP 0 Full Wave Rectified Sine RMS VP 2 VRMS CF 2 AC coupled R...

Страница 107: ...VP Rectified square AC coupled RMS VP 2 VRMS CF 2 VP 0 Pulse t T VRMS VP where D duty cycle D 1 D t T D 1 D 1 CF AC coupled RMS 0 AC coupled pulse AC coupled peak CF V V V VP 1 D V VPD VP 0 Triangular...

Страница 108: ...es The voltage induced due to magnetic flux is proportional to the area of the loop formed by the input leads Therefore minimize the loop area of the input leads and connect each signal at only one po...

Страница 109: ...aused by the offset of the TRMS converter This offset will not affect reading accuracy and should not be zeroed out using the REL feature The following equation expresses how this offset VOFFSET is ad...

Страница 110: ...switching modules it must be in the R in position WARNING To prevent electric shock never make or break connections while power is present in the test circuit Frontpanelinputs When using the front pa...

Страница 111: ...or ACI 3 Use the RANGE and keys to select a measurement range consistent with the expected current or press AUTO to select autoranging AUTO annunciator turns on Details on range are provided in Sectio...

Страница 112: ...nd other equipment before replacing the AMPS fuse 1 Turn off the power and disconnect the power line and test leads 2 From the front panel gently push in the AMPS fuse holder with a flat blade screwdr...

Страница 113: ...can use offset compensated ohms on the 100 1k and 10k ranges for the 4 function Measurement methods For the 100 to 1M ranges the Model 2701 uses the constant current method to measure resistance The...

Страница 114: ...ce current flows from the INPUT HI to INPUT LO terminals Shielded Cable Optional Shield Resistance Under Test Optional Shield Resistance Under Test Shielded Cable Note Note F 500V PEAK FRONT REAR 3A 2...

Страница 115: ...aired to channel 12 and so on Figure 3 9 2 and 4 connections for Model 7700 switching module Shielding To achieve a stable reading it helps to shield resistances greater than 100k As shown in Figure 3...

Страница 116: ...tching module Do not apply more than 300V DC or 300V RMS 425V peak for AC waveforms between input high H or input low L or switching module damage may occur 5 If using a switching module perform the f...

Страница 117: ...ent I and measures the voltage V The resistance R is then calculated R V I and the reading is displayed For offset compensated ohms two measurements are performed one normal resistance measurement and...

Страница 118: ...Standard resistance measurements page 3 23 procedure NOTE The OCOMP annunciator will flash when the instrument is on an invalid range 100k through 100M ranges for offset compensated ohms Normal ohms m...

Страница 119: ...he constant current method is shown in Figure 3 10 The test current sourced to the DUT depends on the selected measurement range For example for the 100 range the test cur rent is 1mA Since the voltme...

Страница 120: ...to 1M ranges DUT V ISOUR VMEAS Input Hi Input Lo 2701 DUT V ISOUR VMEAS Input Hi Input Lo 2701 Sense Hi Sense Lo A 2 wire ohms 2 measurements 100 through 1M ranges RDUT VMEAS ISOUR RDUT VMEAS ISOUR B...

Страница 121: ...g this process the precision 0 7 A current is sourced through RREF with an open input This reference voltage VREF is measured and RREF is then calculated RREF VREF 0 7 As shown in Figure 3 11B the 4 f...

Страница 122: ...4 measurements 10M and 100M ranges IDUT ISOUR IREF IDUT VMEAS RDUT VMEAS 10M 0 7 A 10M VMEAS Eq 2 V VMEAS ISOUR 0 7uA RREF 10M IREF 2701 RDUT Input Hi Input Lo IDUT V VMEAS ISOUR 0 7uA RREF 10M IREF E...

Страница 123: ...the selected measurement range see resistance specifications in Appendix A When an input lead Hi or Lo is open as shown in Figure 3 12B voltage rises to the open circuit level which trips the OVRFLW m...

Страница 124: ...Lo S W Detection I Source 100 DUT 1mA 6 6V Open Input Lead Sense HI Input HI Input Lo Sense Lo S W Detection I Source 100 DUT 1mA 15mV Open Sense Lead OVR FLW 2701 Reading 100 range OVR FLW 2701 Readi...

Страница 125: ...channel 11 channel 2 is paired to channel 12 and so on This configuration allows up to 10 DUT to be tested The 7701 module has 32 input channels For normal 4 wire ohms measurements up to 16 DUT can be...

Страница 126: ...thermistor is the most sensitive and the 4 wire RTD is the most stable Thermocouples For thermocouples temperature measurement range depends on which type of thermocouple is being used Thermocouples t...

Страница 127: ...two ways for the Model 2701 to acquire the cold junction temperature It can measure the cold junction using a thermistor or 4 wire RTD or the known temperature value can be entered by the user There...

Страница 128: ...measure temperature Be sure to electrically insulate the transducer leads to keep them from making contact with other conductors When you close channel 1 to measure the cold junction temperature that...

Страница 129: ...sitive It can quickly detect minute changes in temperature It is a good choice when measuring very small changes in temperature The downside for this increased sensitivity is the loss of linearity Sin...

Страница 130: ...changes with changes in temperature The Model 2701 measures the resistance and calculates the temperature reading When using default RTD parameters the resistance of the RTD will be 100 at 0 C Of all...

Страница 131: ...not have to be maintained at the simulated reference temperature i e immersed in ice bath For the Model 7700 switching module you can also use a simulated reference junction as shown in Figure 3 14B...

Страница 132: ...eference junction Model 7700 Thermocouple Thermocouple Thermocouple C Internal reference junction Model 7700 H L CH 1 20 Model 7700 Switching Module Thermocouple Ice Bath Copper wire to thermocouple w...

Страница 133: ...ue DIN Red Black Japanese Red White Japanese Red White French Yellow Black French Yellow Blue K U S Yellow Red R U S Black Red British Brown Blue British White Blue DIN Red Green DIN Red White Japanes...

Страница 134: ...are connected to its paired channel 11 through 20 Channel 1 is paired to channel 11 channel 2 is paired to channel 12 and so on Figure 3 16 4 wire RTD connections Model 2701 Input HI Input LO A Front...

Страница 135: ...provided in Table 3 3 After pressing SHIFT and then SENSOR the menu starts at step 1 to select measurement units Each time you press ENTER to make a selection the menu will automatically go to the nex...

Страница 136: ...Select thermocouple type 4 JUNC SIM INT or EXT Select the SIMulated INTernal or EXTernal reference junction SIM 000 C to 065 C 273K to 338K or 032 F to 149 F For the SIMulated reference junction set t...

Страница 137: ...own in Table 3 6 you can select the USER sensor type but you cannot change the USER parameters from the front panel The parameters for the USER type can only be set using remote programming see TEMPer...

Страница 138: ...perform the following steps to close the desired channel Keep in mind that for 4 wire RTD measurements you will close the primary INPUT channel 1 through 10 The channel that it is paired to will close...

Страница 139: ...d This method generates constant measurement resolution for any input frequency The multimeter s AC voltage measurement section performs input signal conditioning Gate time The gate time is the amount...

Страница 140: ...odel7700switchingmodule Connections for the Model 7700 switching module are shown in Figure 3 18 For this 2 wire measurement channels 1 through 20 can be used Figure 3 18 FREQ and PERIOD connections u...

Страница 141: ...nnel a Press the CLOSE key b Use and to key in the channel number and press ENTER The previously closed channel if there is one will open and the specified channel will close NOTE While in the normal...

Страница 142: ...he INPUTS switch must be in the F out position For switching modules it must be in the R in position Frontpanelinput When using the front panel input terminals connect the test leads to the INPUT HI a...

Страница 143: ...play the resistance readings If the measured circuit is above the threshold level the instrument will not beep and either display the resistance reading or the message OPEN If the reading is below 110...

Страница 144: ...Select measurement function SENSe 1 Optional root command FUNCtion name clist Select measurement function name VOLTage DC VOLTage AC CURRent DC CURRent AC RESistance FRESistance CONTinuity FREQuency o...

Страница 145: ...TEMPerature THERmistor NRf clist Set thermistor type in ohms NRf 1950 to 10050 5000 TEMPerature FRTD TYPE name clist Select FRTD type name PT100 D100 F100 PT3916 PT385 or USER PT100 e TEMPerature FRTD...

Страница 146: ...FETCh Return reading s READ Trigger and return reading s Channel list parameter clist SCH where S Mainframe slot number 1 or 2 CH Switching module channel number must be 2 digits Examples 101 Slot 1 C...

Страница 147: ...Invalid function in scanlist will occur when trying to query the state of offset compensated ohms for that channel FRES OCOM ON 101 Details on scanning are provided in Section 7 b FRESistance OCOMpen...

Страница 148: ...sed to specify the expected input level The instrument will then automatically select the most sensitive current or voltage threshold range g FREQuency APERture n clist PERiod APERture n clist The rat...

Страница 149: ...are automatically stored in the buffer In order to return multiple reading strings continuous initiation must be disabled INIT CONT OFF so that the sample count SAMPle COUNt which specifies the number...

Страница 150: ...using the example named Ohmm in Table G 1 of Appendix G RST One shot measurement mode INIT CONT OFF FUNC FRES Select 4 function FRES RANG 1e3 Select 1k range FRES OCOM ON Enable offset compensated oh...

Страница 151: ...entqueries NOTE For more information on read commands see Section 8 Triggering Section 13 SCPI Signal Oriented Measurement Commands and Appendix D Signal Processing Sequence and Data Flow FETCh Whatit...

Страница 152: ...e ABORt command take the trigger model out of idle equivalent to the INIT command and return a reading equivalent to a FETCh query This command will always return a new reading since aborting the trig...

Страница 153: ...if the default settings for a measurement are appropriate and speed is not a requirement SENSe 1 DATA FRESh Whatitdoes This query is similar to FETCh in that it returns the latest reading from the ins...

Страница 154: ...to readings that have math applied to them e g MX B scaling Examples One shotreading DCvolts notrigger fastestrate RST SENSe FUNCtion VOLTage DC SENSe VOLTage DC RANGe 10 Use fixed range for fastest...

Страница 155: ...ger DELay AUTO ON Note Auto trigger delay only takes effect with trigger source set for BUS or EXTernal SENSe FUNCtion VOLTage DC SENSe VOLTage DC RANGe AUTO ON INITiate external trigger SENSe DATA FR...

Страница 156: ...etails on selecting display resolution Includes the commands for remote programming Rate and bandwidth Provides details on integration rate and bandwidth for AC measurements Includes the commands for...

Страница 157: ...ncy measurements from 3Hz to 500kHz and period measurements from 2 s to 333 s can be made on the ACV ranges TEMP There is no range selection for temperature measurements Temperature measurements are p...

Страница 158: ...matically selects the best range to measure the applied signal Auto ranging should not be used when optimum speed is required Note that the AUTO key has no effect on temperature TEMP Up ranging occurs...

Страница 159: ...ON CURRent AC RANGe n clist Select ACI range n 0 to 3 A 3 CURRent AC RANGe AUTO b clist Control ACI auto range b ON or OFF ON RESistance RANGe n clist Select 2 range n 0 to 120e6 120e6 RESistance RAN...

Страница 160: ...the automatically selected range value When auto range is disabled the instrument remains at the selected range When a valid RANGe n command is sent auto ranging disables Rangeprogrammingexamples NOTE...

Страница 161: ...on To set display resolution press the DIGITS key until the desired number of digits is displayed Scanning When a simple scan is configured the present digits setting will apply to all channels in the...

Страница 162: ...mands Commands Description Default SENSe 1 Optional root command VOLTage DC DIGits n clist Set of digits for DCV n 4 to 7 7 VOLTage AC DIGits n clist Set of digits for ACV n 4 to 7 6 CURRent DC DIGits...

Страница 163: ...PLC from the bus results in increased reading noise and fewer usable digits while the slowest integration time 5 PLC from the front panel 50 PLC from the bus provides the best common mode and normal...

Страница 164: ...ium and SLOW NPLC settings are ignored see Bandwidth page 4 10 for details From the front panel setting the rate for one function affects all the other functions For example if you set DCV for medium...

Страница 165: ...1200 digitized samples 1 2s When the Medium bandwidth 30Hz to 300kHz is chosen the same circuit is used However only 120 samples 120ms are needed for an accurate calculation because the analog RMS con...

Страница 166: ...002 to x 2 4 5 0 VOLTage AC APERture n clist Set rate for ACV in secs n 3 333e 5 to 1 4 Note 3 CURRent DC NPLCycles n clist Set rate for DCI in PLCs n 0 002 to x 2 5 0 CURRent DC APERture n clist Set...

Страница 167: ...Rf 3 to 3e5 5 30 Channel list parameter clist SCH where S Mainframe slot number 1 or 2 CH Switching module channel number must be 2 digits Examples 101 Slot 1 Channel 1 101 203 Slot 1 Channel 1 and Sl...

Страница 168: ...the normal A D conversion method is used therefore the integration rate commands can be used The default bandwidth setting is 30 for both ACV and ACI If you want to set an integration rate for an AC f...

Страница 169: ...wo digital filter types moving and repeating The moving average filter uses a first in first out stack where the newest reading conversion replaces the oldest An aver age of the stacked reading conver...

Страница 170: ...filter resets and the filter starts processing again starting with a new initial conversion value from the A D converter The noise window which is expressed as a percentage of range or maximum temper...

Страница 171: ...ature reading The maximum temperature depends on which thermocouple is being used For example for a Type J thermocouple the maximum reading is 760 C a 10 window means that the filter window is 76 C Fo...

Страница 172: ...A3 A2 A1 A1 A1 Rdg 3 A4 A3 A2 A1 A1 Rdg 4 A5 A4 A3 A2 A1 Rdg 5 A6 A5 A4 A3 A2 Rdg 6 B1 B1 B1 B1 B1 Rdg 7 B2 B1 B1 B1 B1 Rdg 8 B3 B2 B1 B1 B1 Rdg 9 B4 B3 B2 B1 B1 Rdg 10 B5 B4 B3 B2 B1 Rdg 11 Filter co...

Страница 173: ...splay the number of readings to filter 1 to 100 and press ENTER 5 Use the or key to display the desired filter type moving or repeating and press ENTER The filter turns on and the instrument returns t...

Страница 174: ...nd if the moving filter is selected the filter will not enable when the scan is run For the advanced scan filter state on or off and count can be set for each channel You cannot set unique filter coun...

Страница 175: ...ONtrol name Select filter type name MOVing or REPeat Note 2 VOLTage AC AVERage WINDow NRf Set filter window in NRf 0 to 10 0 1 VOLTage AC AVERage COUNt n clist Specify filter count n 1 to 100 10 VOLTa...

Страница 176: ...filter window in NRf 0 to 10 0 1 TEMPerature AVERage COUNt n clist Specify filter count n 1 to 100 10 TEMPerature AVERage STATe b clist Enable or disable the filter Note 3 Channel list parameter clis...

Страница 177: ...r window to 0 01 CURR AVER COUN 10 Set to filter 10 readings CURR AVER ON Enable filter Example 2 The following command sequence configures channels 101 through 115 of the Model 7700 to use the repeat...

Страница 178: ...or remote programming Ratio and channel average Explains how to use these calculations to display the ratio or average of two switching channels dB Explains how to use remote programming to configure...

Страница 179: ...range Selecting a range that cannot accommodate the rel value does not cause an overflow condition but it also does not increase the maximum allowable input for that range For example on the 10V range...

Страница 180: ...e rel setting Details to configure and run a scan are provided in Section 7 For an advanced scan the following general procedure shows how to configure a scan channel to use rel 1 While in the normal...

Страница 181: ...rel value Rel commands for ACV SENSe 1 Optional root command VOLTage AC REFerence n clist Specify rel value n 757 5 to 757 5 V 0 VOLTage AC REFerence STATe b clist Enable disable rel b ON or OFF OFF V...

Страница 182: ...rence n clist Specify rel value n 0 to 1 5e7 Hz 0 FREQuency REFerence STATe b clist Enable disable rel b ON or OFF OFF FREQuency REFerence ACQuire clist Use input signal as rel value Rel commands for...

Страница 183: ...n the DCV function the only valid acquire command is VOLT DC REF ACQ Also if the instrument is overflowed OVERFLOW or a read ing has not been triggered an execution error 200 occurs when ACQuire is se...

Страница 184: ...d from the MATH menu mX b percent and reciprocal 1 X Figure 5 1 shows the MATH menu tree Note that the settings shown in the menu tree are the factory defaults NOTE The various instrument operations i...

Страница 185: ...ement the digit value To change range place the cursor on the multiplier and use the and keys m 0 001 1 K 1000 and M 1 000 000 With the cursor on the polarity sign the and keys toggle polarity 4 Press...

Страница 186: ...ay the present reference value REF 1 000000 factory default 3 Key in the reference value The and keys control cursor position and the and keys increment decrement the digit value To change range place...

Страница 187: ...be displayed 0 4 R Reciprocal 1 X configuration 1 Press SHIFT and then MATH to display the math menu 2 Press the RANGE or key to display 1 X and press ENTER The MATH annunciator will turn on and the...

Страница 188: ...d 22 are available for DCI and ACI Channels 1 through 20 are available for all other functions 4 If using a switching module REAR inputs selected use the or key to select close the input channel If us...

Страница 189: ...1 CALCulate 1 KMATh MBFactor NRf clist Set mX b b factor NRf 4294967295 to 4294967295 0 CALCulate 1 KMATh MUNits char clist Set mX b units see Setting mX b units X CALCulate 1 KMATh PERCent NRf clist...

Страница 190: ...e value is set using PERCent NRf the PERCent query command returns the programmed value When reference is set using ACQuire the PERCent query com mand returns the acquired reference value Reading math...

Страница 191: ...nable math calculation ROUT CLOS 101 Close channel 101 CALC DATA Read mX b result for channel 101 ROUT CLOS 102 Close channel 102 CALC DATA Read mX b result for channel 102 Example 2 The following com...

Страница 192: ...ary channel It then opens the primary channel and closes and measures the paired channel Ratio or channel average is then calculated from the two readings and displayed If the Model 2701 is configured...

Страница 193: ...l average calculation To disable channel average again press SHIFT and then CH AVG 5 When finished there are two ways to disable the calculation Press the OPEN key The calculation will disable and the...

Страница 194: ...a scan are provided in Section 7 Advanced scan configuration notes 1 When a calculation ratio or channel average is enabled for a primary scan chan nel the following setup actions occur The calculatio...

Страница 195: ...t panel The 0 5s default delay keeps the relays from cycling too fast Setting a shorter delay may shorten the life of the relays It does not matter which of the two commands you use to set the delay T...

Страница 196: ...he result of the calculation Example 2 The following command sequence configures channels 103 and 105 for the ratio and channel average calculations When channel 103 is scanned the ratio calculation i...

Страница 197: ...the ratio VIN VREF The largest negative value of dB is 160dB This will accommodate a ratio of VIN 1 V and VREF 1000V dBconfiguration Remote programming must be used to configure the Model 2701 for dB...

Страница 198: ...e Table 5 4 dB commands Commands Description Def DCV dB commands UNITs VOLTage DC name Select DCV measurements name V or DB V UNITs VOLTage DC DB REFerence n Set reference in volts n 1e 7 to 1000 1 AC...

Страница 199: ...eadings Discusses the various statistics available on buffer data including minimum and maximum values average mean standard deviation and peak to peak values Remote programming buffer Summarizes the...

Страница 200: ...buffer operations occur Frontpanelbuffer Auto clear With buffer auto clear enabled the buffer is cleared readings lost before a new storage operation starts The buffer can be manually cleared by sett...

Страница 201: ...owever front panel FACTory defaults enables buffer auto clear Enabling disablingbufferautoclear 1 Press SHIFT and then SETUP 2 Use the and keys to display the present state of buffer auto clear BUF AU...

Страница 202: ...when the instrument is turned back on If you have readings stored in the buffer and auto clear is disabled when the unit is turned off subsequent stored readings will be appended to the old group of r...

Страница 203: ...ress ENTER Storingreadings Perform the following steps to store readings 1 Set up the Model 2701 for the desired configuration 2 Press the STORE key 3 Use the and keys to specify the number of reading...

Страница 204: ...ting the buffer reading number by 100 and then finally by 1 000 When you get close to the desired reading number release the or key Again press and hold in the or key to scroll one reading at a time F...

Страница 205: ...ate mean where y is the average Xi is a stored reading n is the number of stored readings RDG NO 10 Reading Value Time Date RDG NO 9 Reading Value Time Date RDG NO 8 Reading Value Time Date RDG NO 7 R...

Страница 206: ...h readings in the buffer that were stored in that manner you cannot use the INIT or READ command if sample count is 1 error 225 out of memory NOTE The measurement event register can be read to check w...

Страница 207: ...name Set buffer control name NEVer NEXT or ALWays NEV h TRACe DATA Read all readings in the buffer i TRACe DATA SELected start count Specify readings to be returned start starting point count number o...

Страница 208: ...STem TSTamp TYPE and TRACe TSTamp TYPE Both of these commands query the timestamp type However SYSTem TSTamp TYPE queries the timestamp that will be used for the next storage operation while TRACe TST...

Страница 209: ...timestamp at a time NOTE Changing the timestamp format clears the buffer The timestamp will only be included with a returned buffer reading if it is specified as a data element see FORMat ELEMents h...

Страница 210: ...u can use TRACe NEXT to determine the buffer location for the next stored reading For example if the last reading is stored at memory location 36 TRACe NEXT will return the value 37 This query is usef...

Страница 211: ...rned by TRACe DATA can include from one to all five data elements shown in the above item list For example if you want the units and reading number included with the reading you would send this comman...

Страница 212: ...stamp will be included in the output data m CALCulate2 FORMat name Select buffer statistic CALCulate2 STATe ON OFF Control on off buffer statistic CALCulate2 IMMediate Calculate datain buffer CALCulat...

Страница 213: ...named BufStats in Table G 1 of Appendix G Store readings TRAC CLE AUTO ON Enable buffer auto clear TRAC POIN 20 Set buffer size to 20 TRAC FEED SENS Select raw readings for storage TRAC FEED CONT NEXT...

Страница 214: ...scan Covers other scan options including delay monitor auto configuration saving setups and auto scan Scan operation Provides the step by step procedures to perform a basic scan a manual external tri...

Страница 215: ...and exercise its operation before the switching module is installed in the Model 2701 Use the following commands to install 7700 pseudocards in empty slots SYSTem PCARd1 C7700 Install 7700 pseudocard...

Страница 216: ...m the front panel For a sequential scan the scan proceeds from the lowest numbered channel to the highest For example assume channels 101 102 105 108 and 109 are selected for a scan The scan will run...

Страница 217: ...process is to 1 open any closed channels 2 close the primary displayed channel and perform a measurement 3 open the primary channel 4 close the paired channel and perform a measurement 5 calculate an...

Страница 218: ...and Figure 7 2 for SCAN operation Figure 7 1 Trigger model with STEP function Enable Scan Control Source Immediate External Timer Event Detection Output Trigger Another Reading Trigger Counter Reading...

Страница 219: ...er Scan Trigger Counter Yes No Close First Chan in List Open Last Chan Close Next Chan in List Ratio Chan Average Delay Measurement Process Device Action Output Trigger Another Reading Yes No Sample C...

Страница 220: ...701 outputs a trigger pulse If programmed to again scan the channels in the scan list the Model 2701 will wait at the control source for another trigger event After all the scan list channels are agai...

Страница 221: ...conds The timer resets to its initial state when the scan is completed STEP operation As shown in Figure 7 1 the timer control source affects the timing between scanned channels SCAN operation As show...

Страница 222: ...us With manual delay selected the user can set the delay period from 0 seconds to 99 hours 99 minutes 99 999 seconds However if you set a delay shorter than the corresponding auto delay period measure...

Страница 223: ...scan list If you set the reading count to 10 or less one scan of the 10 channels will be performed If you set the reading count to any value from 11 to 20 two scans will be performed A reading count f...

Страница 224: ...d channel to the highest Non sequential backward scanning is only intended to be performed using remote programming Unexpected results may occur if a non sequential scan is run from the front panel Fo...

Страница 225: ...he configured scan can be saved in a user saved setup SAV0 SAV1 SAV2 SAV3 or SAV4 For a front panel configured scan the reading count and timer values are also saved B04 and later software However if...

Страница 226: ...annel MAX CHAN for the scan These settings determine the number of channels in the scan For example if you set MIN CHAN to 101 and MAX CHAN to 110 there will be 10 channels in the scan list The starti...

Страница 227: ...tup menu the displayed information indicates the present setup for the selected channel The position of the decimal point in the SETUP message indicates present range Examples S ETUP V 101 1V range fo...

Страница 228: ...channels 101 through 120 will assume the DCV setup Note that channels for slot 2 are not affected When you press the 4 function key for a primary channel the subsequently paired channels will be disp...

Страница 229: ...ll assume the same setup Note however that channels for slot 2 are not affected NOTE For the Model 7700 DCI and ACI cannot be selected for channels 101 through 120 and channels 201 through 220 DCI and...

Страница 230: ...T default and press ENTER To use the timer use the or key to display TIMER YES and press ENTER The timer interval is displayed in the hour minute second format The timer can be set from 0 001 sec 00H...

Страница 231: ...are used to set the delay See Table 7 1 for details NOTE The delay for ratio and channel average can only be set using remote programming Table 5 3 Monitor channel While in the normal measurement stat...

Страница 232: ...ON annunciator turns on Method 2 1 If a channel is closed press OPEN to open it 2 Press SHIFT and then MONITOR 3 Use the and keys to display the monitor channel i e MONITOR 101 and press ENTER The mon...

Страница 233: ...ing N or Y and press the or key to change the setting 4 Press ENTER to return to the normal measurement state NOTES Auto channel configuration cannot be enabled if there is a non scan channel presentl...

Страница 234: ...or to change the setting 4 Press ENTER to exit from the menu structure NOTE With auto scan enabled DO NOT save the present setup as the power on default setup If you do so an interrupted scan will not...

Страница 235: ...d will cause the message HALT SCANNER to be displayed 6 To disable the scan press SHIFT and then HALT Buffer To recall scanned readings stored in the buffer press RECALL and use the and keys to naviga...

Страница 236: ...closes The reading count determines how many channel measurements will be performed during the scan sequence If the reading count is greater than the scan list length operation loops back to the begin...

Страница 237: ...ing steps to run a monitor scan NOTE The last enabled scan function STEP or SCAN will be used for the monitor scan 1 Perform Step 1 and Step 2 of the Advanced scan setup procedure page 7 16 to set up...

Страница 238: ...ber of channels to scan Table 7 1 4 While in the normal measurement state select and enable the monitor channel as explained in Scan configuration Monitor channel page 7 18 When the reading limit for...

Страница 239: ...tiate one scan cycle READ Initiate one scan cycle and request sample readings More information on using these commands is provided by Reference c that follows Table 7 1 Control sources For bus operati...

Страница 240: ...nerate error 700 Invalid function in scanlist Buffer For front panel scanning the reading count specifies the number of readings to store in the buffer For remote scanning the sample count specifies t...

Страница 241: ...67295 to 4294967295 1 0 CALCulate3 LIMit1 LOWer n Set low limit 1 for monitor n 4294967295 to 4294967295 1 0 CALCulate3 LIMit2 UPPer n Set high limit 2 for monitor n 4294967295 to 4294967295 2 0 CALCu...

Страница 242: ...n starts with channel 101 and proceeds to channel 105 After channel 105 is scanned the unit backs up to scan channel 103 then proceeds forward to scan channels 106 through 110 Example 2 The scan start...

Страница 243: ...y scan list When the scan is changed to a 4 wire function the scan list will change For example assume the above scan is changed to the 4 function as follows SENS FUNC FRES 101 110 For the 4 wire resi...

Страница 244: ...s the number of scans to perform If the sample count is greater than the number of channels in the scan list scan list length operation wraps around to the beginning of the scan list and continues For...

Страница 245: ...remote programming commands Where appropriate menu sequences are provided to summarize a front panel operation or selection For example SHIFT SETUP RESTORE FACT For the above menu sequence press SHIFT...

Страница 246: ...he Model 2701 waits for an external trigger When the trigger is received channels 101 and 102 are measured Operation then returns to the control source where it waits for another trigger NOTE After th...

Страница 247: ...SOR Select thermocouple sensor SENS TCOUPLE TEMP TRAN TC 101 Select type K thermocouple TYPE K TEMP TC TYPE K 101 Select internal reference junction JUNC INT TEMP RJUN RSEL INT 101 b Channel 102 Selec...

Страница 248: ...tion is shown in Figure 7 5 while the procedure steps and programming commands are listed in Table 7 3 In Figure 7 5 notice that there are two modes of operation While in the monitor mode the Model 27...

Страница 249: ...or scan example 30 C 4 Measurements Measure TEMP Close Monitor Channel 101 No Yes Measure Open Last Chan Close Next Chan Close First Channel Return to Monitor Mode No Yes SCAN Monitor Mode Scan Mode 2...

Страница 250: ...1 Set limit to 30 SHIFT LIMITS HI1 30 00000 CALC3 LIM1 UPP 30 101 Enable on limit SHIFT OFF ON LIMITS ON CALC3 LIM1 STAT ON 101 Close channel 101 ROUT CLOS 101 Enable Channel Average SHIFT CH AVG CAV...

Страница 251: ...feature which is used to screen out readings that are not within a specified reading window External triggering Explains external triggering which allows the Model 2701 to trigger and be triggered by...

Страница 252: ...stay in idle Operation will continuously fall through the idle state and proceed to the Event Detection block of the trigger model When in the one shot trigger mode RST default setup the TRIG key must...

Страница 253: ...over the Ethernet or RS 232 Trigger command TRG is received over the Ethernet or RS 232 Delay auto or manual A programmable delay is available after event detection It can be set manually or an auto...

Страница 254: ...and keys The maximum is 99H 99M 99 999S Note that pressing the AUTO key sets the delay to 0 001 sec Press ENTER to accept the delay or EXIT for no change Table 8 1 Auto delay settings Function Range a...

Страница 255: ...back to the beginning of the Device Action as shown in Figure 8 2 The hold count specifies how many readings have to be within the window before it is accepted See Reading hold autosettle page 8 6 fo...

Страница 256: ...out of window reading occurs to restart the hold process For remote operation the hold process seeks a new seed once it has been satisfied and the reading has been released For basic front panel oper...

Страница 257: ...three external sources trigger link digital I O and the TRIG key When EX TRIG is pressed the TRIG annunciator lights and dashes are displayed to indicate the instrument is waiting for an external tri...

Страница 258: ...led the Model 2701 will not respond to an input trigger Details on the Digital I O are provided in Section 9 Externaltrigger The EXT TRIG input requires a falling edge TTL compatible pulse with the sp...

Страница 259: ...User s Manual Triggering 8 9 Figure 8 4 Trigger link input pulse specifications EXT TRIG Triggers on Leading Edge TTL High 2V 5V TTL Low 0 8V 2 s Minimum 2701 900 01 book Page 9 Wednesday August 3 20...

Страница 260: ...ts The specifications for this trigger pulse are shown in Figure 8 5 Typically you would want the Model 2701 to output a trigger after the settling time of each measurement Figure 8 5 Trigger link out...

Страница 261: ...complements the trigger lines on the Model 2701 For this example the Models 2701 and 7002 are configured as follows Model 2701 Factory defaults restored accessed from SHIFT SETUP External triggers acc...

Страница 262: ...NAL OPERA TOR SERVICEABLE P ARTS SERVICE BY QUALIFIED PERSONNEL ONL Y WARNING CHANNEL READY O U T I N DIGITAL I O A1 A2 A3 A4 A5 TRIGGER LINK IEEE 488 LINE RA TING EXTERNAL TRIGGER 90 260V 47 440Hz 85...

Страница 263: ...on the Model 2701 places it at point A in the flowchart where it is waiting for an external trigger B Pressing STEP on the Model 7002 takes it out of the idle state and places operation at point B in...

Страница 264: ...next DUT The process continues until all 400 channels are scanned measured and stored in the buffer External triggering with BNC connections An adapter cable is available to connect the micro DIN Tri...

Страница 265: ...l 220 Current Source External Trigger Trigger Link WARNING NO INTERNAL OPERATOR SERVICABLE PARTS SERVICE BY QUALIFIED PERSONNEL ONLY CAUTION FOR CONTINUED PROTECTION AGAINST FIRE HAZARD REPLACE FUSE W...

Страница 266: ...y measure or step scan operations The following commands will return operation to the top of the trigger model idle at the START point of the trigger model ABORt RCL 0 1 2 or 3 SYSTem PREset RST What...

Страница 267: ...Initiate Trigger Source Immediate Trigger Source External Trigger Source Timer Trigger Source Manual Trigger Source BUS Trigger Delay n Trigger Delay AUTO b Another Trigger Output Trigger Another Samp...

Страница 268: ...user set Delay period The Timer interval can be set from 0 to 999999 999 seconds The timer source is only available during scan operation The timer resets to its initial state when the instrument goe...

Страница 269: ...b Enable disable continuous initiation ON or OFF Note 1 c FETCh Request the last reading s d READ Perform an ABORt INITiate and a FETCh d TRIGger SOURce name Select control source IMMediate TIMer MAN...

Страница 270: ...et the interval f DELay AUTO b The auto delay times are listed in Table 8 1 Disabling auto delay sets the delay time to 0 g TRIGger SIGNal Send this action command to bypass the control source when yo...

Страница 271: ...s of limit tests Remote programming limits and digital output Summarizes the commands to perform limit tests and control the digital I O port Application sorting resistors Provides an application to t...

Страница 272: ...faults Limit 1 HI1 1V and LO1 1V Limit 2 HI2 2V and LO2 2V Keep in mind that a limit value for Limit 2 does not have to exceed the Limit 1 value For example Limit 2 can be set to 1V and Limit 1 can be...

Страница 273: ...it testing There are three beeper options NEVER OUTSIDE and INSIDE These options are explained as follows NEVER With this option the beeper is disabled OUTSIDE With this option the beeper sounds when...

Страница 274: ...ess of or will increase or decrease the reading by a factor of 10 3 Key in the low limit for Limit 1 LO1 and press ENTER 4 Key in the high limit for Limit 2 HI2 and press ENTER 5 Key in the low limit...

Страница 275: ...V Trigger In is disabled by setting pin 8 low 0V NOTE External triggering is covered in Section 8 1 Digital Output 1 low limit 1 2 Digital Output 2 high limit 1 3 Digital Output 3 low limit 2 4 Digita...

Страница 276: ...ital Output 5 Master Limit logical OR of the four above limits When a limit LO1 HI2 LO2 HL2 is reached the digital output line for that limit will be pulled high or low When a reading is within the li...

Страница 277: ...time and enable disable pulse output are listed in Table 9 2 See Digital output commands in the table The pulse time does not affect measurement speed If a subsequent in limit reading occurs while the...

Страница 278: ...des connect the external supply voltage to pin 7 of the digital I O port Make sure the external supply voltage is between 5V and 33V and the current required by the device does not exceed 250mA CAUTIO...

Страница 279: ...ll Up Resistor Pin 9 Digital Ground Digital Output Pin 7 Diode Clamp Relay Coil Relay Coil External Power 5V to 33V External Power 5V to 33V Model 2701 Transistor Switch Flyback Diode Equivalent Circu...

Страница 280: ...gital ground As a result a low logic output 0V is provided at the output If the second input B of the NAND gate is connected to another output line of the port the output of the NAND gate will go to l...

Страница 281: ...wise press to move the cursor to the right press or key to display Y or N and press ENTER 5 Use the key to display the present logic sense LSENSE setting HIGH or LOW 6 If you want to retain the presen...

Страница 282: ...294967295 to 4294967295 2 CALCulate3 LIMit2 STATe b clist Enable disable Limit 1 test b ON or OFF a CALCulate3 LIMit2 FAIL Query test result 0 pass in 1 fail high or low b CALCulate3 LIMit2 CLEar Clea...

Страница 283: ...ator will turn on and the number 2 will be displayed NOTE When limits are disabled from the front panel both Limit 1 and Limit 2 disable for remote operation b CALCulate3 LIMit1 FAIL CALCulate3 LIMit2...

Страница 284: ...OUTP LSEN ALOW Set logic sense to active low CALC3 OUTP ON Enable digital outputs READ Trigger and request reading CALC3 LIM1 FAIL Request result of limit 1 test Application sortingresistors For this...

Страница 285: ...are calculated as follows R1 100 1 R5 100 5 100 0 01 100 0 05 1 5 The high and low limits are then calculated as follows HI Limit 1 100 R1 HI Limit 2 100 R5 100 1 100 5 101 105 LO Limit 1 100 R1 LO L...

Страница 286: ...For resistors 5 no beep will sound Place these resistors in Bin 3 Remote Operation For remote operation make sure both Limit 1 and Limit 2 are enabled The following table evaluates the three possible...

Страница 287: ...eading LO limit 2 LO limit 1 HI limit 1 HI limit 2 Resistor tolerance bin Affected outputs Pass Pass Pass Pass 1 1 None Pass Fail Pass Pass 5 2 1 and 5 Pass Pass Fail Pass 5 2 2 and 5 Fail Fail Pass P...

Страница 288: ...to remote operation Ethernet setup Shows some typical Ehternet systems covers connections and explains how to select and configure the Ethernet Front panel aspects of Ethernet operation Summarizes er...

Страница 289: ...s installed you can take the Model 2701 out of remote and use the front panel When the instrument is turned off the pseudocard will be lost uninstalled Autozero Autozero is part of the normal measurem...

Страница 290: ...on scan channel setup DCV input divider Using remote programming you can enable the DCV input divider for the 100mV 1V and 10V ranges When enabled the input resistance for these DCV ranges are reduced...

Страница 291: ...yes clear Press ENTER The password commands are listed in Table 10 1 The password commands are used to perform the following operations Disable or enable the use of a password Disabling the use of a p...

Страница 292: ...protected 2 Using an incorrect password in a password command causes error 221 settings conflict 3 The present password and command protection state are not affected by RST or SYSTem PRESet Battery S...

Страница 293: ...yes STATus Returns OK MEMORY LOST or CHARGING FAILURE Memory is lost when the battery is not installed and upon a reset after a firmware upgrade A charging failure occurs when it is time for a new bat...

Страница 294: ...to 100 meters in length Figure 10 1 Direct 2701 connection to PC KEITHLEY SLOT COVER TRIGGER LINK ETHERNET 10 100 BaseT Link Act 100bT RS 232 WARNING NO INTERNAL OPERATOR SERVICABLE PARTS SERVICE BY...

Страница 295: ...two groups of users Finally Figure 10 4 shows a simplified diagram of a network system using a router or servers KEITHLEY SLOT COVER TRIGGER LINK ETHERNET 10 100 BaseT Link Act 100bT RS 232 WARNING N...

Страница 296: ...VICE BY QUALIFIED PERSONNEL ONLY CAUTION FOR CONTINUED PROTECTION AGAINST FIRE HAZARD REPLACE FUSE WITH SAME TYPE AND RATING MADE IN U S A SLT 2 SLT 1 DIGITAL I O EXT TRIG CAT I Keithley 2701 Increase...

Страница 297: ...onnector of the PC hub or receptacle Figure 10 5 RJ 45 Ethernet cable male male RJ 45connectorstatusLEDs The female RJ 45 connector shown in Figure 10 6 has two status LEDs located at the top of the c...

Страница 298: ...RVICABLE PARTS SERVICE BY QUALIFIED PERSONNEL ONLY CAUTION FOR CONTINUED PROTECTION AGAINST FIRE HAZARD REPLACE FUSE WITH SAME TYPE AND RATING MADE IN U S A SLT 2 SLT 1 DIGITAL I O EXT TRIG CAT I ETHE...

Страница 299: ...can be made from either the front panel or remote programming NOTE Error code 550 Unitialized Ethernet module will occur on power up if the Ethernet settings are corrupt or the MAC address is FF FF F...

Страница 300: ...ET menu SET Ethernet Ethernet settings can be changed using the flowchart in Figure 10 8 For the IP Address Subnet and Gateway the setting is divided into four parts 1 through 4 The settings shown in...

Страница 301: ...value SUBNET2 255 Press ENTER Use edit keys to change value SUBNET3 255 Press ENTER Use edit keys to change value SUBNET4 000 Press ENTER Use edit keys to change value GATEWAY1 192 Press ENTER Use edi...

Страница 302: ...unicate Ethernet and RS 232 commands SELect name Select communications mode ETHernet or SERial ETHernet Ethernet ADDRess value Set IP address of 2701 n n n n ADDRess Query IP address of 2701 MASK valu...

Страница 303: ...continuously take readings Readings responses to queries and any error messages are displayed in the control panel Take Measurements Click Initiate to start continuous readings SCPI Programming Type...

Страница 304: ...e and resets it to DEFAULT With the web page open the use of password can be enabled and changed if desired Configurationsummary The configuration summary shown in Figure 10 9 provides the various det...

Страница 305: ...10 18 Remote Operations Model 2701 User s Manual Figure 10 9 Model 2701 Configuration internal web page 2701 900 01 book Page 18 Wednesday August 3 2011 9 43 AM...

Страница 306: ...you add the system error query for instance TRIG COUN 20 SYST ERR to make sure errors did not occur from the sent command For example append SYST ERR to the end of any command to check the status How...

Страница 307: ...L key are locked out When REM is turned off the instrument is in the local state and front panel operation is restored NOTE If SYSTem RWLock is in effect LOCAL will be locked out If TRIGger SOURce is...

Страница 308: ...nd word and the parameter is required Brackets Some command words are enclosed in brackets These brackets are used to denote an optional command word that does not need to be included in the program m...

Страница 309: ...est allowable value When the MAXimum parameter is used the instrument is programmed to the largest allowable value Examples ARM TIMer 0 1 Sets timer to 100 msec ARM TIMer DEFault Sets timer to 0 1 sec...

Страница 310: ...lowable value TRIGger TIMer MAXimum Queries the largest allowable value Case sensitivity Common commands and SCPI commands are not case sensitive You can use upper or lower case and any case combinati...

Страница 311: ...mark query or a non optional number included in the command word you must include it in the short form version Example delay del Command words or characters that are enclosed in brackets are optional...

Страница 312: ...ing two commands in one program message stat oper stat oper enab NRf When the above is sent the first command word is recognized as the root command stat When the next colon is detected the path point...

Страница 313: ...that you start over at the root command UsingcommonandSCPIcommandsinthesamemessage Both common commands and SCPI commands can be used in the same message as long as they are separated by semicolons A...

Страница 314: ...ed by commas The following example shows the response message for a program message that contains four single item query commands 0 1 1 0 Responsemessageterminator RMT Each response is terminated with...

Страница 315: ...adings by pressing LOCAL and then EXIT The next command to send buffer data i e TRACe DATA will start at the beginning rather than where the transmission was halted Baudrate The baud rate is the rate...

Страница 316: ...provided in Section 12 XonXoFF is the FACT and RST default flow control setting If NONE is the selected flow control then there will be no signal handshaking between the controller and the Model 2701...

Страница 317: ...the ON state and then press ENTER NOTE Enabling ON the RS 232 interface disables OFF the Ethernet Disabling the RS 232 interface enables the Ethernet Changing the state reboots the Model 2701 3 To re...

Страница 318: ...200 2400 4800 9600 19200 38400 57600 or 115200 BAUD Query baud rate PACE name Control Xon Xoff flow control XON on or NONE off PACE Query state of flow control TERMinator name Select output terminator...

Страница 319: ...the RS 232 interface and Table 10 4 shows the pinout for the connector If your computer uses a DB 25 connector for the RS 232 interface you will need a cable or adapter with a DB 25 connector on one...

Страница 320: ...e Appendix C for RS 232 error messages 800 through 808 Table 10 5 PC serial port pinout Signal DB 9 pin DB 25 pin DCD data carrier detect 1 8 RXD receive data 2 3 TXD transmit data 3 2 DTR data termin...

Страница 321: ...tatus byte and service request SRQ Explains how to program the Status Byte to generate service requests SRQs Shows how to use the serial poll sequence to detect SRQs Status register sets Provides bit...

Страница 322: ...it will set to indicate that an SRQ has occurred Statusregistersets A typical status register set is made up of a condition register an event register and an event enable register A condition register...

Страница 323: ...r Questionable Condition Register Questionable Event Register 0 2 3 5 6 Cal 7 9 10 11 12 13 15 1 Temp Warn 0 2 3 5 6 Cal 7 9 10 11 12 13 15 1 Temp Warn 0 2 3 5 6 Cal 7 9 10 11 12 13 15 1 Temp Warn Out...

Страница 324: ...bits of the following event registers to 0 1 Standard Event Register Operation Event Register Measurement Event Register Questionable Event Register STATus PRESet Reset all bits of the following enabl...

Страница 325: ...parameter value For example if you wish to sets bits B4 B3 and B1 the binary value would be 11010 where B4 1 B3 1 B1 1 and all other bits are 0 When you use one of the other formats convert the binary...

Страница 326: ...end decimal values and does not use a header The following examples show the proper parameter syntax for setting Bits B5 B3 and B2 b101100 Binary format NDN parameter type h2C Hexadecimal format NDN p...

Страница 327: ...B0 are set The returned value can be in the binary decimal hexadecimal or octal format The FORMat SREGister command is used to select the data format for the returned value see Table 11 2 For non dec...

Страница 328: ...e solely dependent on the summary messages 0 or 1 For example if the Standard Event Register is read its register will clear As a result its summary message will reset to 0 which in turn will reset th...

Страница 329: ...d Service request enable register The generation of a service request is controlled by the Service Request Enable Register This register is programmed by you and is used to enable or disable the setti...

Страница 330: ...on page 11 22 NOTE The following example can be run from the KE2700 Instrument Driver using the example named PollSRQ in Table G 1 of Appendix G CLS Clear Error Queue SRE 4 Enable EAV FORM SREG BIN S...

Страница 331: ...and OPC Figure 11 4 Standard event status Bit B1 Not used Bit B2 Query Error QYE Set bit indicates that you attempted to read data from an empty Output Queue ESR PON B7 URQ B6 CME B5 EXE B4 DDE B3 QYE...

Страница 332: ...g module card has been lost Error 524 Unsupported card detected The Model 2701 has detected an installed Model 77XX switching module that is not supported by the current version of firmware Bit B4 Exe...

Страница 333: ...s settled or the filter is disabled Bit B9 Not used Bit B10 Idle State Idle Set bit indicates the Model 2701 is in the idle state Bits B11 through B15 Not used Figure 11 5 Operation event status OR Id...

Страница 334: ...he user specified number of readings have been stored in the buffer The TRACe NOTify command specifies the number of stored readings that will set this bit see Section 6 for details Bit B7 Buffer Avai...

Страница 335: ...13 BQF B12 HL B11 BOF B10 BF B9 BHF B8 BAV B7 BN B6 RAV B5 HL2 B4 LL2 B3 HL1 B2 LL1 B1 ROF B0 OR To Measurement Summary Bit MSB of Status Byte Register ML Master Limit BTF Buffer Three quarter Full BQ...

Страница 336: ...Cal Set bit indicates that an invalid calibration constant was detected during the power up sequence The instrument will instead use a default calibration constant This error will clear after success...

Страница 337: ...eading registers page 11 7 Table 11 4 Condition register commands Command Description STATus OPERation CONDition Read Operation Condition Register STATus MEASurement CONDition Read Measurement Conditi...

Страница 338: ...ummary of the register will set to 1 which in turn sets the summary bit of the Status Byte Register The commands to program and read the event enable registers are listed in Table 11 6 For details on...

Страница 339: ...ters commands Command Description ESE NDN or NRf Program Standard Event Enable Register ESE Read Standard Event Enable Register STATus OPERation ENABle NDN or NRf Program Operation Event Enable Regist...

Страница 340: ...example STB may return decimal 17 The binary bit pattern for decimal 17 is as follows B7 B6 B5 B4 B3 B2 B1 B0 0 0 0 1 0 0 0 1 STB returns decimal 17 B4 and B0 set If in your program you logically AND...

Страница 341: ...is finished While readings are being triggered and stored in the buffer the following command STB can be put into a program loop to continuously read the status byte STB Read status register By maski...

Страница 342: ...error and status messages When an error or status event occurs a message that defines the error status is placed in the Error Queue When a message is placed in the Error Queue the Error Available EAV...

Страница 343: ...nable command along with the null list parameter as follows STATus QUEue ENABle Programmingexample readerrorqueue The following example can be run from the KE2700 Instrument Driver using the example n...

Страница 344: ...12 CommonCommands 2701 900 01 book Page 1 Wednesday August 3 2011 9 43 AM...

Страница 345: ...ommands have been executed B OPC Operation complete query Places an ASCII 1 into the output queue when all pending selected device operations have been completed C OPT Option query Returns the model n...

Страница 346: ...r Summary Status bit in the Status Byte Register will set When used with the immediate initiation command INITiate the OPC bit in the Standard Event Status Register will not set until the Model 2701 g...

Страница 347: ...measure store process is finished C OPC OperationCompleteQuery Placea 1 intheoutputqueueafter allpendingoperationsarecompleted Description When this common command is sent an ASCII 1 will be placed i...

Страница 348: ...YST PRES Returns 2701 to default setup NOTE The following commands take a long time to process and may benefit from using OPC or OPC RST and SYST PRES RCL and SAV ROUT MULT CLOS and ROUT MULT OPEN Onl...

Страница 349: ...ble setup memory If a recall error occurs the setup memory defaults to the SYSTem PRESet values NOTE OPC or OPC should be used with SAV and RCL which are slow responding commands Details on OPC and OP...

Страница 350: ...subsequent bus trigger will also trigger a single measurement NOTE The following example can be run from the KE2700 Instrument Driver using the example named BusTrg in Table G 1 of Appendix G RST Res...

Страница 351: ...Model 2701 returns to idle By sending the WAI command after the INITiate command all subsequent commands will not execute until the Model 2701 goes back into idle The TRG command issues a bus trigger...

Страница 352: ...13 SCPISignalOriented MeasurementCommands 2701 900 01 book Page 1 Wednesday August 3 2011 9 43 AM...

Страница 353: ...d measurement command summary Command Description CONFigure function rang res clist FETCh READ MEASure function rang res clist Places the Model 2701 in a one shot measurement mode for the specified fu...

Страница 354: ...ter is used and it is not a clist it is interpreted as the range parameter rang If two parameters are used and the second one is not a clist the first parameter is the range parameter rang and the sec...

Страница 355: ...er value and the selected range sets the number of display digits As shown above with the 100V range selected and res 0 1 a 100V reading will be displayed as 100 0 V 3 digits The display will default...

Страница 356: ...ent and acquire a reading see READ When this command is sent without the clist parameter the Model 2701 will be configured as follows The function specified by this command is selected If specified ra...

Страница 357: ...ng strings continuous initiation must be disabled INIT CONT OFF so that the sample count SAMPle COUNt which specifies the number of measurements to be performed can be set 1 After INITiate is sent to...

Страница 358: ...D command will generate error 213 init ignored It can be disabled by sending INITiate CONTinuous OFF The RST command can also be used to disable continuous initiation It also places the Model 2701 in...

Страница 359: ...f the res parameter value and the selected range sets the number of display digits As shown above with the 100V range selected and res 0 1 a 100V reading will be displayed as 100 0 V 3 digits The disp...

Страница 360: ...ABORt CONFigure function READ When ABORt is executed the instrument goes into the idle state if continuous initiation is disabled If continuous initiation is enabled the operation re starts at the beg...

Страница 361: ...TemCommands FORMat commands Covers the SCPI commands to configure the format that readings are transmitted Miscellaneous SYSTem commands Covers miscellaneous SYSTem commands 2701 900 01 book Page 1 We...

Страница 362: ...ormat are shown in Figure 14 1 An overflow reading is returned as 9 9E37 When a specified data element has invalid data associated with it NAN Not A Number will be the response NAN is returned as 9 9E...

Страница 363: ...number 000 indicates that no channel was closed Limits For the ASCII data format limit test results are returned as a 4 bit binary number abcd where a High limit 2 b Low limit 2 c High limit 1 d Low...

Страница 364: ...CPI standard being used by Model 2701 Example response message 1996 0 SYSTem KEY NRf Parameters 1 SHIFT key 15 Cursor right arrow key 2 DCV key 16 TEMP key 3 ACV key 17 LOCAL key 4 DCI key 18 EX TRIG...

Страница 365: ...automatically enable Parameters b 0 Disable beeper 1 Enable beeper Figure 14 2 Key press codes 1 2 3 4 5 6 7 8 16 11 17 18 26 27 19 20 28 29 21 22 30 31 23 24 32 14 15 13 12 RANGE F 500V PEAK FRONT RE...

Страница 366: ...15 SCPIReferenceTables 2701 900 01 book Page 1 Wednesday August 3 2011 9 43 AM...

Страница 367: ...acters do not have to be included in the program message Do not use brackets in the program message Angle brackets are used to indicate parameter type Do not use angle brackets in the program message...

Страница 368: ...to 4294967295 2 0 MBFactor clist Query b factor 2 MA0Factor clist Query b factor 2 MUNits char Specify units for mx b reading 3 X MUNits Query mx b units PERCent NRf clist Set target value for PERCen...

Страница 369: ...ic sense of all limit lines AHIGh or ALOW AHIGh LSENse Query logic sense of limit lines LIMit1 Path to control LIMIT 1 test UPPer Path to configure upper limit DATA n clist Set upper limit 4294967295...

Страница 370: ...MBFactor and MA0Factor commands perform the same operations 3 For mX b units char one character A through Z degrees symbol or ohms symbol 4 ON is the RST default parameter and OFF is the SYSTem PRESet...

Страница 371: ...channel to be monitored Sec 7 STATe b Enable or disable channel monitoring OFF STATe Query state of channel monitoring DATA Returns the most recent monitor reading POINts NRf For a monitor scan speci...

Страница 372: ...can NVOLatile b Enable or disable nonvolatile memory for scanning autoscan Note 2 NVOLatile Query nonvolatile memory setting LSELect name Enable INTernal or disable NONE scan NONE LSELect Query state...

Страница 373: ...WINDow Query Hold window COUNt NRf Set Hold count 2 to 100 5 COUNt Query Hold count STATe NRf Enable or disable Hold OFF STATe Query state of Hold CAVerage Channel average calculation Sec 5 DELay NRf...

Страница 374: ...solution REFerence n clist Specify reference 1010 to 1010 0 Sec 5 STATe b clist Enable or disable reference OFF STATe clist Query state of reference ACQuire clist Use input signal as reference REFeren...

Страница 375: ...ist Specify reference 757 5 to 757 5 0 Sec 5 STATe b clist Enable or disable reference OFF STATe clist Query state of reference ACQuire clist Use input signal as reference REFerence clist Query refere...

Страница 376: ...esolution 4 to 7 7 Sec 4 DIGits clist Query resolution REFerence n clist Specify reference 3 1 to 3 1 0 Sec 5 STATe b clist Enable or disable reference OFF STATe clist Query state of reference ACQuire...

Страница 377: ...ist Specify reference 3 1 to 3 1 0 Sec 5 STATe b clist Enable or disable reference OFF STATe clist Query state of reference ACQuire clist Use input signal as reference REFerence clist Query reference...

Страница 378: ...t resolution 4 to 7 7 Sec 4 DIGits clist Query resolution REFerence n clist Specify reference 0 to 120e6 0 Sec 5 STATe b clist Enable or disable reference OFF STATe clist Query state of reference ACQu...

Страница 379: ...REFerence n clist Specify reference 0 to 120e6 0 Sec 5 STATe b clist Enable or disable reference OFF STATe clist Query state of reference ACQuire clist Use input signal as reference REFerence clist Q...

Страница 380: ...ATe clist Query state of reference ACQuire clist Use input signal as reference REFerence clist Query reference value AVERage Path to configure and control filter Sec 4 TCONtrol name Select filter type...

Страница 381: ...ce temperature THERmistor Path to configure thermistor Sec 3 TYPE NRf clist Set thermistor type in ohms 1950 to 10050 5000 TYPE clist Query thermistor type FRTD Path to configure 4 wire RTD Sec 3 TYPE...

Страница 382: ...t threshold range 0 to 1010 10 RANGe clist Query threshold range PERiod Path to configure period Sec 3 APERture n clist Sets gate time for period measurements in seconds 0 01 to 1 0 1 0 Sec 4 APERture...

Страница 383: ...e temperature TEMPerature RJUNction RSELect name clist Select reference junction SIMulated INTernal or EXTernal TEMPerature RJUNction RSELect clist Query reference junction TEMPerature RJUNction SIMul...

Страница 384: ...s QUEue Path to access error queue NEXT Read the most recent error message Note 4 ENABle list Specify error and status messages for queue Note 5 ENABle Read the enabled messages DISable list Specify m...

Страница 385: ...or disable autozero ON STATe Query autozero LSYNc Path to control line synchronization Sec 3 STATe b Enable or disable line sync OFF STATe Query state of line sync LFRequency Query power line frequenc...

Страница 386: ...nel 0 no isolated channels END Request the last isolated channel 0 no isolated channels AOUTput Path to query analog output channels STARt Request highest numbered analog output channel 0 analog outpu...

Страница 387: ...Tamp Path to set timestamp Sec 6 TYPE name Select timestamp type RELative or RTCLock REL TYPE Query timestamp type that will be used for the next buffer storage RELative Path to reset relative timesta...

Страница 388: ...isables protected commands CENable password Enables protected commands STATe b Returns 0 if password protected commands are disabled Returns 1 if enabled NEW password Set new password COMMunicate Ethe...

Страница 389: ...aking RTS name Enable IBFull or RFR or disable OFF hardware handshaking RTS Query state of hardware handshaking SEND data Send data from serial port to another instrument 4 ENTer Read data from serial...

Страница 390: ...Ce POINts value 50 NOTify Query trace notify value NEXT Query buffer location for next stored reading TSTamp Path to set timestamp format FORMat name Select timestamp format ABSolute or DELTa ABS FORM...

Страница 391: ...o 999999 999 sec 0 AUTO b Enable or disable auto delay ON AUTO Query state of delay DELay Query delay SOURce name Select control source IMMediate TIMer MANual BUS or EXTernal IMM SOURce Query control...

Страница 392: ...voltage units Sec 5 DC name clist Select DCV measurement units V or DB V DB Path to set DB reference voltage REFerence n Specify reference in volts 1e 7 to 1000 1 REFerence Query reference DC clist Qu...

Страница 393: ...A Specifications 2701 900 01 book Page 1 Wednesday August 3 2011 9 43 AM...

Страница 394: ...A 2 Specifications Model 2701 User s Manual Model2701Ethernet DataAcquisitionSystem Put 2701 specs here 2701 900 01 book Page 2 Wednesday August 3 2011 9 43 AM...

Страница 395: ...urrent and resistance calculations are performed in exactly the same manner using the pertinent specifications ranges and input signal values CalculatingACcharacteristicsaccuracy AC characteristics ac...

Страница 396: ...t can be shown that a measurement of 0 998815V on the 1V range has an uncertainty of 36 9644mV or 0 998778V to 0 998852V using one year specifications Expressing 0 998778V as dBm and expressing 0 9988...

Страница 397: ...or 10 036mV to 9 964mV Applying the voltage reading accuracy into the dB equation yields Thus the actual reading accuracy is 60dB 0 031213dB to 60dB 0 031326dB dBm and dB for other voltage inputs can...

Страница 398: ...best accuracy AC voltage and AC current Select 6 digits 10 PLC filter ON up to 100 readings fixed range Temperature Select 6 digits 10 PLC filter ON up to 100 readings Optimizingmeasurementspeed The c...

Страница 399: ...B Model7700ConnectionGuide 2701 900 01 book Page 1 Wednesday August 3 2011 9 43 AM...

Страница 400: ...e or a RST command is issued Connections to DMM functions for system channel operation are provided through the card backplane connector Current provided through two protected channels Channels 21 and...

Страница 401: ...te 3A 3A To Model 2701 Backplane Channel 25 See Note Backplane Isolation Channel 24 See Note Backplane Isolation Channels 23 and 25 in this schematic refer to the designations used for control and are...

Страница 402: ...he highest voltage that is connected For example if 1000V is connected to the front panel input the test lead insulation for the switching module must also be rated for 1000V WARNING Dangerous arcs of...

Страница 403: ...3 H L CH4 H L CH5 H L CH6 H L CH7 H L CH8 H L CH9 H L CH10 H L H L CH21 H L CH22 AMPS LO H L CH11 H L CH12 H L CH13 H L CH14 H L CH15 H L CH16 H L CH17 H L CH18 H L CH19 H L CH20 INPUT SENSE H L H L C...

Страница 404: ...ystem For example if 1000V is applied to the front terminals of the DMM the plug in module wiring must be rated for 1000V 1 Make sure all power is discharged from the Model 7700 module 2 Access the sc...

Страница 405: ...L CH21 H L CH22 AMP S LO H L CH11 H L CH12 H L CH13 H L CH14 H L CH15 H L CH16 H L CH17 H L CH18 H L CH19 H L CH20 INPUT SENSE H L H L CH1 H L CH2 H L CH3 H L CH4 H L CH5 H L CH6 H L SENSE OHMS 4 WIR...

Страница 406: ...thermistor connections Figure B 6 4 Wire and RTD connections Figure B 7 Current connections AC or DC Figure B 8 Voltage connections AC or DC Figure B 9 Figure B 5 Thermocouple connections Figure B 6 2...

Страница 407: ...connections Figure B 8 Current connections AC or DC Channel 1 HI LO Channel 10 HI LO Channels 2 9 Channel 11 HI LO Channel 20 HI LO Channels 12 19 Resistor or 4 Wire RTD Resistor or 4 Wire RTD Channel...

Страница 408: ...or AC Connection log Make a copy of Table B 1 and affix it to the cover of the Model 7700 Use this to record connection information and channel descriptions as needed Channel 1 HI LO Channel 20 HI LO...

Страница 409: ...Color Description AMPS COM H L INPUT H L SENSE H L CH1 H L CH2 H L CH3 H L CH4 H L CH5 H L CH6 H L CH7 H L CH8 H L CH9 H L CH10 H L CH11 H L CH12 H L CH13 H L CH14 H L CH15 H L CH16 H L CH17 H L CH18...

Страница 410: ...C StatusandErrorMessages 2701 900 01 book Page 1 Wednesday August 3 2011 9 43 AM...

Страница 411: ...am currently running Illegal program name Cannot create program Expression error Hardware missing Data corrupt or stale Out of memory Illegal parameter value Too much data Parameter data out of range...

Страница 412: ...ed Too many digits Exponent too large Invalid character in number Numeric data error Header suffix out of range Undefined header Program mnemonic too long Header separator error Command header error M...

Страница 413: ...r Re entering the idle layer Filter settled Reading overflow Low limit 1 event High limit 1 event Low limit 2 event High limit 2 event Reading available Buffer user selectable event Buffer available B...

Страница 414: ...or 1k 4 w full scale error 10k 4 w full scale error 100k 4 w full scale error 1M 4 w full scale error 10M 4 w full scale error 10m adc zero error 100m adc zero error 10m adc full scale error 100m adc...

Страница 415: ...ror Temperature Cold Cal error Analog output zero error Analog output pos gain error Analog output neg gain error 1k 4 w dckt Ioff zero error 1k 4 w dckt Ion zero error 1k 4 w dckt Ioff full scale err...

Страница 416: ...rd calibration dates lost Saved setup scancard mismatch Card relay counts lost EE EE EE EE EE EE EE EE EE EE EE EE EE EE EE EE 523 524 525 550 555 556 558 610 611 700 800 802 803 805 808 900 Card hard...

Страница 417: ...D SignalProcessing SequenceandDataFlow 2701 900 01 book Page 1 Wednesday August 3 2011 9 43 AM...

Страница 418: ...signal into a DC voltage that is applied to the A D converter The A D Conversion Process measures the DC signal voltage and internal voltages that correspond to offsets zero and amplifier gains For TC...

Страница 419: ...s through to the next enabled feature or to the display Figure D 2 Signal processing using instrument features Input Signal Rel Math mX b Percent or Reciprocal Rel ed reading Reading Rel value Y mX b...

Страница 420: ...are two types of filters moving and repeating A filter stack is used to temporarily store the specified number of readings to be averaged In general for the moving filter each measurement process adds...

Страница 421: ...operations see Math page 5 7 Limits The reading that is applied to the Limits block in the flow chart is not modified and is the reading that is displayed on the Model 2701 With Limits enabled the re...

Страница 422: ...en closes and that reading is used as the Chan B value for the calculation Ratio or Ch Avg is then calculated as shown in Figure D 3 As shown the result of Ratio or Ch Avg can then be used by an enabl...

Страница 423: ...gering configuration is summarized by the block diagram shown in Figure D 4 Refer to this block diagram for the following discussion Figure D 4 Data flow for remote operation SENSe Measurement Filter...

Страница 424: ...tiation and TRIGger COUNt 1 configures the instrument to perform one measurement cycle The INIT command can then be used to initiate the measurement cycle When the INIT command is sent the programmed...

Страница 425: ...hat do not change will indicate that the same data array is being returned NOTE The FORMat ELEMents command see Section 14 is used to include the reading number RNUM element in each data array SENS 1...

Страница 426: ...affect data in the sample buffer Therefore subsequent executions of FETCh acquire the same data NOTE When an instrument setting that is relevant to the readings in the sample buffer is changed the FE...

Страница 427: ...he sample buffer Therefore subsequent executions of these commands return the same data With no math function enabled these commands return the last data array stored in the sample buffer CALC3 LIM1 F...

Страница 428: ...ad operation CALC2 IMM or CALC2 DATA is performed However if there was no calculation previously performed the number 9 910000E 37 will instead be returned Continuousmeasurementmode With continuous in...

Страница 429: ...data for each subsequent scan will overwrite the data stored in the sample buffer and data store Once the scan is properly configured INIT or READ will start the scan READ also returns the scanned rea...

Страница 430: ...E MeasurementConsiderations 2701 900 01 book Page 1 Wednesday August 3 2011 9 43 AM...

Страница 431: ...which is available from Keithley Thermoelectricpotentials Thermoelectric potentials thermal EMFs are small electric potentials generated by differences in temperature at the junction of dissimilar me...

Страница 432: ...ure of A junction C or K In the unlikely event that the two junction temperatures are identical no thermal EMFs will be generated More often the two junction temperatures will differ and considerable...

Страница 433: ...t to prevent future oxidation In some cases connecting the two thermal junctions together with good thermal contact to a common heat sink may be required Unfortunately most good electrical insulators...

Страница 434: ...he peak to peak noise is five times the rms value 99 of the time the peak to peak noise can be equated as follows For example with a source resistance of 10k the noise over a 0 5Hz bandwidth at room t...

Страница 435: ...ields so care must be taken to keep the Model 2701 voltage source and connecting cables a good distance away from these potential noise sources Radiofrequencyinterference RFI Radio Frequency Interfere...

Страница 436: ...e voltage between the LO terminals of the two instruments This voltage will be added to the source voltage affecting the accuracy of the measurement Figure E 2 Power line ground loops Figure E 3 shows...

Страница 437: ...8 Measurement Considerations Model 2701 User s Manual Figure E 3 Eliminating ground loops Instrument 1 Power Line Ground Instrument 2 Instrument 3 2701 900 01 book Page 8 Wednesday August 3 2011 9 43...

Страница 438: ...ference from such noise sources as line frequency and RF fields can seriously corrupt measurements rendering experimental data virtually useless In order to minimize noise a closed metal shield surrou...

Страница 439: ...del 2701 is RI and the voltage measured by the nanovoltmeter is VM Figure E 5 Meter loading The voltage actually measured by the meter is attenuated by the voltage divider action of RS and RI and it c...

Страница 440: ...ple temperature Thermistor equation Documents the Steinhart Hart equation which is used to calculate thermistor temperature RTD equation Documents the Callendar Van Dusen equation which is used to cal...

Страница 441: ...sted in Table F 1 through Table F 8 Table F 1 Type B inverse function polynomial 250 C to 700 C 291 V to 2 431 V 700 C to 1 820 C 2 431 V to 13 820 V c0 c1 c2 c3 c4 c5 c6 c7 c8 Error 9 842 332 1 101 6...

Страница 442: ...C E is the measured voltage in microvolts Table F 3 Type J inverse function polynomial 210 C to 0 C 8 095 V to 0 V 0 C to 760 C 0 V to 42 919 V 760 C to 1 200 C 42 919 V to 69 553 V c0 0 0 0 0 3 113...

Страница 443: ...6 C to 0 05 C t90 c0 c1E c2E2 c3E3 ciEi where t90 is the calculated temperature in C E is the measured voltage in microvolts Table F 5 Type N inverse function polynomial 200 C to 0 C 3 990 V to 0 V 0...

Страница 444: ...1E c2E2 c3E3 ciEi where t90 is the calculated temperature in C E is the measured voltage in microvolts Table F 7 Type S inverse function polynomial 50 C to 250 C 235 V to 1 874 V 250 C to 1 200 C 1 87...

Страница 445: ...o use with the Model 2701 Table F 8 Type T inverse function polynomial 200 C to 0 C 5 603 V to 0 V 0 C to 400 C 0 V to 20 872 V c0 0 0 0 0 c1 2 594 919 2 10 2 2 592 800 10 2 c2 2 131 696 7 10 7 7 602...

Страница 446: ...le F 9 3 Select a thermistor that closely matches the A B and C constants in Table F 9 4 Analyze the differences between the two sets of curve fitting constants to determine the affect on measurement...

Страница 447: ...D R0 1 AT BT2 CT3 T 100 where RRTD is the calculated resistance of the RTD R0 is the known RTD resistance at 0 C T is the temperature in C A alpha 1 delta 100 B 1 alpha delta 1e 4 C 1 alpha beta 1e 8...

Страница 448: ...follows A 0 00385 1 1 4999 100 0 00385 1 014999 0 003907746 B 1 0 00385 1 4999 1e 4 1 0 005774615 1e 4 5 774615e 7 The resistance of the RTD at 100 C R100 is then calculated as follows R100 R0 1 AT B...

Страница 449: ...ta values A and B are calculated as follows A 0 003920 1 1 49710 100 0 003920 1 014971 0 003978686 B 1 0 003920 1 49710 1e 4 1 0 005868632 1e 4 5 868632e 7 C 1 0 003920 0 10630 1e 8 1 0 000416696 1e 8...

Страница 450: ...G KE2700InstrumentDriver Examples 2701 900 01 book Page 1 Wednesday August 3 2011 9 43 AM...

Страница 451: ...command sequence examples that are used throughout this manual These examples include a reference to appropriate manual section in the References column of the tables Visual Basic and CVI C examples...

Страница 452: ...nnels ACV 1V range 1 channel 4 wire RTD temperature Measurement speed rate 1 plc Filter Disabled no filtering Buffer Store 160 reading strings Buffer elements include reading only Triggering Timer sca...

Страница 453: ...trings 20 4 reading strings Buffer elements include reading only Limits DCV scan Limit 1 all channels 20mV Master Latch enabled Triggering Bus control source Data retrieval SRQ if limit fails Advance5...

Страница 454: ...t the buffer and data retrieval will have to be modified to accommodate the number of scanned channels Modules that have cold junction include 7700 and 7706 modules 20 available TC channels 7708 modul...

Страница 455: ...n See 7706 packing list Demonstrates how to remotely calibrate the analog output channels of the 7706 module BufStats Page 6 15 Prog Ex Demonstrates calculating the mean of 20 readings BusTrg Page 12...

Страница 456: ...strates ratio calculation Ratio2 Page 5 19 Ex 2 Demonstrates ratio and channel average functions ReadError Queue Page 11 23 Prog Ex Demonstrates reading the error queue Relative1 Page 5 6 Ex 1 Demonst...

Страница 457: ...ering Bus control source Simple3 None Use Case 3 Two scans using 7708 module 40 channel DCV 1V range scan 20 channel 4 scan Models 2700 and 2701 100 range Model 2750 10 range dry circuit ohms enabled...

Страница 458: ...ering Buffer Store 40 DCV reading strings 20 4 reading strings Buffer elements include reading only Limits DCV scan Limit 1 all channels 20mV Master Latch enabled Triggering Bus control source Simple5...

Страница 459: ...in mind that the buffer will have to be modified to accommodate the number of scanned channels Modules that have cold junction include 7700 and 7706 modules 20 available TC channels 7708 module 40 av...

Страница 460: ...riggering Bus control source trigger delay 0 125 seconds SOPC Page 12 4 Demonstrates operation complete query OPC SrSetup Page 12 6 Demonstrates saving and recalling user setup TCalibration 7706 Demon...

Страница 461: ...om switching module channels Read multi point from front panel None Demonstrates configuring and reading multiple data points from the front panel input Read single point from switching module channel...

Страница 462: ...inute Data retrieval SRQ when buffer and full Advance3 None Use Case 3 Two scans using 7708 module 40 channel DCV 1V range scan 20 channel 4 scan Models 2700 and 2701 100 range Model 2750 10 range dry...

Страница 463: ...ading strings 20 4 reading strings Buffer elements include reading only Limits DCV scan Limit 1 all channels 20mV Master Latch enabled Triggering Bus control source Data retrieval SRQ if limit fails A...

Страница 464: ...ind that the buffer and data retrieval will have to be modified to accommodate the number of scanned channels Modules that have cold junction include 7700 and 7706 modules 20 available TC channels 770...

Страница 465: ...urce trigger delay 0 125 seconds Data retrieval SRQ when buffer and full Simple1 None Use Case 1 30 channel scan using 7708 module 30 channels DCV 10V range 10 channels type T thermocouple temperature...

Страница 466: ...er Latch enabled Triggering Bus control source Simple4 None Use Case 4 Two scans using 7708 module 40 channel DCV scan 1V range Configuration saved in User Setup 1 20 channel 4 scan Configuration save...

Страница 467: ...e Use Case 6 Scan 160 channels using 7703 module see NOTE Type K thermocouple TC temperature measurements Reference junction Simulated Measurement speed rate 0 01 plc Filter Disabled no filtering Buff...

Страница 468: ...e 400 reading strings Buffer elements include reading only Triggering Bus control source Simple8 None Use Case 8 7706 module in slot 1 and 7702 module in slot 2 7706 module Output analog output values...

Страница 469: ...unciators 1 12 Flashing CHAN 7 15 Flashing OCOMP 3 25 REM 10 20 SRQ 10 20 Aperture 4 12 Applications Sorting resistors 9 14 Auto delay settings 8 4 Auto ranging 4 3 4 5 Autozero 3 4 10 2 Average buffe...

Страница 470: ...eral bus commands Limits and digital output 9 12 Math 5 12 Multiple channel control 2 20 Range 4 4 Ratio and channel average 5 18 Rel 5 4 Scanning 7 27 SCPI see FORMat commands SCPI refer ence tables...

Страница 471: ...ogramming 9 12 Scanning 9 11 Setting 9 10 Sink mode controlling external devices 9 8 Digits 4 6 Commands 4 6 Programming examples 4 7 Remote programming 4 6 Scanning 4 6 Setting 4 7 Display 1 19 Annun...

Страница 472: ...y 15 6 FREQ and PERIOD connections for front panel inputs 3 47 Frequency and period measurements 3 46 Connections 3 47 Front panel input 3 47 Model 7700 switching module 3 47 Gate time 3 46 Procedure...

Страница 473: ...rrent see Current measurements DCI and ACI Frequency and period see Frequency and period measurements One shot mode 13 7 Ranges 4 2 Resistance see Resistance measurements 2 and 4 3 20 Setting speed 4...

Страница 474: ...nual ranging 4 3 4 5 Measurement 4 2 Programming examples 4 5 Remote programming 4 4 Scanning 4 3 Range Digits Rate Bandwidth and Filter 4 1 Rate 4 8 Aperture 4 12 Bandwidth 4 12 Bandwidth conflict er...

Страница 475: ...elding 3 22 Measurement methods 3 25 Constant current 3 26 Effects of open test leads 3 30 Ratiometric 3 28 Offset compensated ohms 3 24 3 25 3 26 3 28 3 30 3 32 Resistors Sorting 9 14 Response messag...

Страница 476: ...Slot numbering 2 6 Software 1 5 Source mode Logic control 9 10 Specifications A 1 Speed Setting measurement speed 4 10 vs noise characteristics 4 8 Standard deviation buffer statistic 6 8 Standard eve...

Страница 477: ...Connections 8 12 Input 9 5 Input pulse specifications EXT TRIG 8 9 Output pulse specifications VMC 8 10 Trigger model Control source and event detection 8 3 Front panel operation 8 2 Front panel scan...

Страница 478: ...operty of Keithley Instruments All other trademarks and trade names are the property of their respective companies Keithley Instruments Corporate Headquarters 28775 Aurora Road Cleveland Ohio 44139 44...

Отзывы:

Нет отзывов

Бренды по названию

Популярные бренды

Загрузить еще бренды