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Aim-TTI LD400, Instruction Manual

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Aim-TTI LD400 Instruction Manual Download Page 35

  

  34 

Remote Interface Configuration  

The LD400P model can be remotely controlled via its RS232, USB, GPIB or LAN interfaces. 

The GPIB interface provides full facilities as described in IEEE Std. 488 parts 1 and 2. 

The RS232 interface communicates directly with a standard COM port.  

The USB interface enumerates as a Communications Class device and interacts with application 
software through a standard virtual COM port device driver on the PC. The instrument firmware 
can be updated in the field via the USB port; see the ‘Maintenance’ chapter for details. 

The LAN interface is designed to meet LXI (Lan eXtensions for Instrumentation) version 
1.4 LXI Core 2011. Remote control using the LAN interface is possible using the TCP/IP Sockets 
protocol.  The instrument also contains a basic Web server which provides information on the 
unit and allows it to be configured from a web browser.  Simple command line control from the 
browser is also possible.   

GPIB Interface  

The standard GPIB interface 24-way connector is located on the instrument rear panel. The pin 
connections are as specified in IEEE Std. 488.1-1987 and the instrument complies with both 
IEEE Std. 488.1-1987 and IEEE Std. 488.2-1987. 

It provides full talker, listener, service request, serial poll and parallel poll capabilities. There are 
no device trigger or controller capabilities. The IEEE Std.488.1 interface subsets provided are: 

 

SH1,  AH1,  T6,  L4,  SR1,  RL2,  PP1,  DC1,  DT0,  C0,  E2. 

The GPIB address of the unit is set from the front panel: from the Home screen select the 

Utilities

 menu then 

Interface Settings

. The present GPIB address is displayed. If it needs to be 

changed, use the rotary knob to set the desired address and then press the 

Confirm

 soft-key.  

The interface will operate with any commercial GPIB interface card, using the device drivers and 
support software provided by the manufacturer of that card. 

RS232 Interface 

 

The 9-way D-type serial interface connector is located on the instrument rear panel. It should be 
connected to a standard PC port preferably using a fully wired 9-way 1:1 male-female cable 
without any cross-over connections.  Alternatively, a 3-way cable can be used, connecting only 
pins 2, 3 and 5 to the PC, but with links made in the connector at the PC end between pins 1, 4 
and 6 and between pins 7 and 8, as shown in the diagram:  

 

Most commercial cables provide these connections.  

In addition to the transmit and receive data lines, the instrument passively asserts pins 1 (DCD) 
and 6 (DSR), actively drives pin 8 (CTS) and monitors pin 4 (DTR) from the PC. This allows the 
use of a fully wired 9-way cable. 

The Baud Rate for this instrument is fixed at 9600; the other parameters are 8 data bits, no parity 
and one stop bit. Flow control uses the XON/XOFF protocol, but because of the low volume of 
data associated with this instrument it is very unlikely that flow control will actually be invoked. 

Summary of Contents for LD400

Page 1: ...LD400 LD400P 400W DC Electronic Loads INSTRUCTION MANUAL ...

Page 2: ...0 Slow Start 21 Introduction to Transient Operation 21 Transient Menu 22 Voltage and Current Limits 24 Short Term or Intermittent Operation at up to 600 Watts 24 Store and Recall Facilities 25 Utilities Menu 26 Analogue Remote Control 27 Application Notes 28 Stability of Source and Load Combinations 29 Dynamic Behaviour in Transient Operation 29 Start up transients 30 Characteristics of each Opera...

Page 3: ...nden Sie im entsprechenden Produktordner der beigefügten CD ROM Diese Informationen können auch von der Support Seite auf der Aim TTi Website heruntergeladen werden Dieses Handbuch trägt die Nummer 48511 1730 Ausgabe 2 Italiano Sicurezza 51 Le istruzioni complete per il funzionamento e la programmazione dello strumento sono incluse nella relativa cartella del prodotto del CD ROM fornito È anche po...

Page 4: ...atedly switch the load between two different operating levels level A and level B The frequency and duty cycle of the transients can be set over a wide range The transients can also be initiated by an external logic signal The transitions between the levels have a true linear slewing characteristic in all modes with the slew rate being adjustable over a wide range The unit meters and displays meas...

Page 5: ...e will conduct 80 Amps max Isolation Voltage 300Vdc max either load input to chassis ground Input Terminals Rear Panel Input Safety terminals accepting 5mm diameter wire or 8mm spades at 80 Amps max or 4mm plugs at 30 Amps max Front Panel Input Safety terminals accepting 4mm diameter wire 4mm plugs or 6 5mm spades 30 Amps max External Voltage Sense Connection Terminal block on rear panel Sense sel...

Page 6: ... at 4A to 2V at 80A Setting Accuracy 0 2 2 digits Regulation 30 mV for 90 load power change using external sense Temperature Coefficient 0 02 1 mV per ºC 2 Slew Rate Ranges 8 V range 0 8 V per s to 80 V per ms 80 V range 8 V per s to 800 V per ms 3 Minimum transition time 150 µs TRANSIENT CONTROL Transient Generator Pulse Repetition Rate Adjustable from 0 01Hz 100 seconds to 10kHz Pulse Duty Cycle...

Page 7: ...terminal block on rear panel Output Impedance 600Ω nominal for 1MΩ load e g oscilloscope Scaling 50mV per Amp 4 Volts full scale Accuracy 0 5 5mV Common Mode Range 3Vdc max to load negative A connection is required see 4 REMOTE CONTROL Digital Remote Interfaces The LD400P model provides LAN USB GPIB and RS232 interfaces for full remote control LAN Ethernet 100 10base T connection with auto cross o...

Page 8: ... 20 to 80 RH Storage Range 40ºC to 70ºC Environmental Indoor use at altitudes up to 2000m Pollution Degree 2 Cooling Variable speed fan Air exit at rear Safety Complies with EN61010 1 EMC Complies with EN61326 Size 130mm H 3U x 212mm W rack x 435mm D Weight 5 7 kg Option 19 inch rack mount kit Specification Notes 1 In 600 Watt short term operation mode the dynamic response is not specified and bot...

Page 9: ... Communities EMC Emissions EN61326 1 2013 Radiated Class B EN61326 1 2013 Conducted Class B EN61326 1 2013 Harmonics referring to EN61000 3 2 2006 Immunity EN61326 1 2013 Immunity Table 1 referring to a EN61000 4 2 2009 Electrostatic Discharge b EN61000 4 3 2006 Electromagnetic Field c EN61000 4 11 2004 Voltage Interrupt d EN61000 4 4 2004 Fast Transient e EN61000 4 5 2006 Surge f EN61000 4 6 2009...

Page 10: ...cles 70 Performance A C 250 cycles 0 Performance B C d EN61000 4 4 2004 Fast Transient 1kV peak AC line 0 5kV peak Load connections Performance B B e EN61000 4 5 2006 Surge 0 5kV line to line 1kV line to ground Performance B B f EN61000 4 6 2009 Conducted RF 3V 80 AM at 1kHz 150kHz 80MHz AC line only all other connections 3m therefore not tested Performance A A According to EN61326 1 the definitio...

Page 11: ...e its rated supply voltages or environmental range WARNING THIS INSTRUMENT MUST BE EARTHED Any interruption of the mains earth conductor inside or outside the instrument will make the instrument dangerous Intentional interruption is prohibited The protective action must not be negated by the use of an extension cord without a protective conductor When the instrument is connected to its supply term...

Page 12: ...s fitted with the required wall plug and an IEC60320 C13 connector for the instrument end This instrument requires a lead rated at 6A for all mains supply voltages WARNING THIS INSTRUMENT MUST BE EARTHED Any interruption of the mains earth conductor inside or outside the instrument will make the instrument dangerous Intentional interruption is prohibited Mounting This instrument is suitable both f...

Page 13: ...load circuit cables and to avoid difficulties with current loops There should be an external connection between the monitor negative and the load negative at some point in the circuit wherever is most convenient except this is not normally necessary for a battery powered portable DMM Rear Panel Connections Load Input The INPUT terminals for the load circuit on the rear panel accept 4mm plugs into ...

Page 14: ...s to be measured normally at the output terminals of the source under test Move the VOLTAGE SENSE SELECT slide switch on the rear panel to the EXT position Ensure that the source is connected with the correct polarity These terminals must not be connected to any voltage other than the source that is connected to the load input Remote Disable Input Apply greater than 3V preferably 5V to the DISABLE...

Page 15: ...ce or Constant Conductance characteristics A fifth mode Constant Voltage operates in a completely different manner to adjust the current to whatever value is needed to obtain the desired voltage from the source Constant and Transient Operation The load offers two independent level settings referred to as Level A and Level B Two keys marked A and B in the LEVEL SELECT area of the front panel allow ...

Page 16: ...distinguishing between the three possible reasons High Power the power limit circuit is operating as described above Dropout the voltage applied from the source is below the setting of the Dropout voltage Low Voltage the power stage is in the minimum resistance condition because the voltage available from the source is insufficient to maintain the current level required The minimum resistance cond...

Page 17: ...ny mode other than Constant Current external voltage sensing leads should be connected from the terminals of the source to the external sense inputs on the rear panel of the load In Constant Current CC mode external voltage sensing only improves the accuracy of the meter readings it does not affect the behaviour of the load To avoid impact on the stability margin do not add phase shift in the sens...

Page 18: ...nd meter readings are shown on the backlit liquid crystal display LCD At power up the instrument initialises to the home screen which is the normal display during operation of the unit This screen displays all of the load meter readings and the most important load parameter settings as described below and is also the top level of the soft key driven menu structure The display changes to show other...

Page 19: ...menus are accessed through the soft keys in one of these sets The major parameters accessible in the first set are Mode To select the operating mode Limits To impose cut off limits on the applied voltage or current values or to enter the 600 Watt short term operation mode Level To enter numeric values for Level A and Level B Dropout To enter a numeric value for the Dropout Voltage Transient To acc...

Page 20: ...ired Similarly multiple presses of the Transient key select between Frequency Duty Cycle and Slew Rate A lamp above each of these keys blinks whilst adjustment is enabled and four cursor soft keys are shown The display of the selected parameter value is expanded to fill its edit box with an adjustment indicator positioned under the digit to be varied The and soft keys can be used to select which d...

Page 21: ...bove Separate settings for both level values are retained for each operating mode There are two ranges for level setting in each of the load operating modes except constant power These differ in both the range of values permitted and the entry resolution the present values are shown in the number prompt Pressing the Range soft key opens the range selection menu with the presently active range high...

Page 22: ...at will occur at low voltages when attaining the desired power requires a high current if the source does not have sufficient current capability to reach the power level demanded See the Application Notes chapter later for a discussion of some of the implications of the fact that constant power mode causes the load to act as a negative resistance In CR constant resistance mode the load will start ...

Page 23: ...ation to be chosen Press the Back soft key to return to the transient menu or the Home key to return to the home screen The soft key label on the transient menu will show either Freq or Period to reflect the most recent choice of representation Transient Duty Cycle Pressing the Duty soft key on the Transient menu opens the Duty cycle setting menu This setting specifies the percentage of each repet...

Page 24: ...me key to return to the home screen Slow Slew Rate Limitations There is a lower limit to the slew rate value that can be used which is determined by the combination of slew rate frequency duty cycle and the difference between the two levels If the requested transition time which is the difference between the level settings divided by the slew rate is longer than the available time which is the osc...

Page 25: ...ches 100 a warning message is shown on the screen To avoid unexpected behaviour the load input is not immediately disabled however the user must either manually switch off the source or the load or at least reduce the dissipation by switching to a lower level setting otherwise the load will automatically disable its input ten seconds after the warning is shown If this trip is allowed to occur then...

Page 26: ... soft key which opens the character entry screen Select a character using the knob or alternatively the digits 0 to 9 and the decimal point can be entered using the numeric keys To enter the selected character press the Enter soft key To delete the previously entered character press either the CE soft key or the CE hard key Use the and soft keys to select the character position The maximum number ...

Page 27: ...Level B Zero for all modes except maximum resistance for CR mode Dropout Voltage 0V Slow Start Off Transient generator 1 Hz at 50 duty cycle Slew rate The Default setting for best calibration of the Level settings Protection Limits Set to None Screen Contrast Adjustment This sub menu offers the choice of white on black or black on white display by using the Invert soft key The screen contrast sett...

Page 28: ...l Voltage Control is enabled the Ext lamp will illuminate and Ext V will be displayed in the status line The internal Level A and Level B parameters no longer have any effect The load mode and full scale range can still be changed in the usual way if required The Dropout Voltage setting remains active if it is set above zero The CONTROL VOLTAGE input has a scaling factor of 4 Volts full scale The ...

Page 29: ...h an electronic load The dropout facility should be used to protect batteries from being damaged by excessive discharge Electronic supplies have active feedback networks whose dynamic characteristics often interact with the load When that load like this instrument also includes an active feedback controlled network whose dynamic characteristics in turn depend on the nature of the source it will be...

Page 30: ...ficant potential for instability Many supplies have L C output filters to reduce noise these introduce extra phase shift into the overall source and load combination and can increase the possibility of instability If there is no damping across the inductor a resonant circuit can be formed which allows oscillations to build up to significant amplitude Remedial Actions The compensation networks of t...

Page 31: ...nts can be generated The reason for this is that as soon as the load is enabled the internal feedback loop will attempt to conduct the current demanded by the level setting In the absence of a source voltage this will result in the gate drivers applying maximum bias voltage to the power FETs reducing their resistance to minimum 25mΩ in an attempt to force a current to flow This is the condition th...

Page 32: ...current The fact that the current rises as the voltage falls means that the load is acting as a negative resistance This behaviour is also exhibited by most switch mode power supply circuits This characteristic raises the possibility of a latch up condition if the source has a significant output impedance To explain this consider the possibility that the source voltage falls slightly perhaps becau...

Page 33: ...diode and provides an alternative to Constant Voltage mode see below but without the extreme stability problems of that mode Constant Voltage Mode Constant Voltage mode is more likely to exhibit instability than any other mode especially when used in conjunction with electronically regulated sources It is primarily useful with true wideband current sources which maintain their high output impedanc...

Page 34: ...de which will double both the current handling and power dissipation capability of a single unit The connections to the source should be matched as well as possible Note that additional stability issues may arise because of phase response differences between the units the use of more than two units in parallel is not recommended Multiple unit operation should not be attempted in any operating mode...

Page 35: ...ies The IEEE Std 488 1 interface subsets provided are SH1 AH1 T6 L4 SR1 RL2 PP1 DC1 DT0 C0 E2 The GPIB address of the unit is set from the front panel from the Home screen select the Utilities menu then Interface Settings The present GPIB address is displayed If it needs to be changed use the rotary knob to set the desired address and then press the Confirm soft key The interface will operate with...

Page 36: ...sign a COM port number to this particular unit This number will depend on previous COM port assignments on this PC and it may be necessary to use Device Manager to discover it Each instrument has a unique USB identifier which is remembered by the system so it will receive the same COM port number whenever it is attached to the same PC regardless of the physical interface socket used even though th...

Page 37: ...essed by IP address the first time spaces are not allowed The name then appears in the local domain e g myLD400 local if the accessing device is configured to support the protocol which is the case with most modern PCs The default name is t followed by the serial number ICMP Ping Server The unit contains an ICMP server allowing the instrument to be pinged using its IP address as a basic communicat...

Page 38: ...ddress if name resolution is working TCP Sockets The instrument uses 2 sockets on TCP port 9221 for instrument control and monitoring Text commands are sent to this port as defined in Remote Commands and any replies are returned via the same port Any command string must contain one or more complete commands Multiple commands may be separated with either semicolons or line feeds No final terminator...

Page 39: ...s registers directly The instrument specific Input State and Input Trip Registers record events related to the electrical function of the load and its interaction with the source under test The Standard Event Status Register supported by the Execution Error and Query Error registers records events concerned with command parsing and execution and the flow of commands queries and responses across th...

Page 40: ...led Reports the present state of the input enable setting The bits in the Input State Register continually reflect the present state of the condition they report The register can be read by the ISR query but this does not change the state of the contents On power up it is normally set to 1 input disabled unless the power up option on the Utilities menu has been set to retain the previous state The...

Page 41: ...orresponding mask register if any of these errors occurs then bit 4 of the Standard Event Status Register will be set This bit can be masked from any further consequences by clearing bit 4 of the Standard Event Status Enable Register Status Byte Register STB and GPIB Service Request Enable Register SRE These two registers are implemented as required by the IEEE Std 488 2 Any bits set in the Status...

Page 42: ...CK error arises if the response formatter is waiting to send a response message and the input queue becomes full This will cause the Query Error bit to be set in the Standard Event Status Register a value of 2 to be placed in the Query Error Register and the response formatter to be reset discarding the waiting response message The parser will then start parsing the next PROGRAM MESSAGE UNIT from ...

Page 43: ...P OVER CURRENT TRIP OVER VOLTAGE TRIP 600W DURATION TRIP ITR OPP 7 5 4 3 2 1 0 6 INPUT DISABLED 7 5 4 3 2 1 0 6 7 5 4 3 2 1 0 6 7 5 4 3 2 1 0 6 DIS INPUT LIMITING 0 0 0 0 0 0 Register Summary Set Query Name ITR Input Trip Register ITE ITE Input Trip Enable Register ISR Input State Register ISE ISE Input State Enable Register EER Execution Error Register QER Query Error Register ESR Standard Event ...

Page 44: ...ge has been read by the controller before the parser is allowed to start the next command in the input queue On all other interfaces the response message is immediately sent into buffers in the physical layer Remote Command Formats Commands are sent as PROGRAM MESSAGES by the controller each consisting of zero or more PROGRAM MESSAGE UNIT elements separated if there is more than one such element b...

Page 45: ...a decimal point or a unit NR2 A fixed point number with a fractional part but no exponent part NR3 A floating point number with both a fractional part and an exponent part CRD Character Response Data consisting of the text characters listed When helpful numbers are followed by a units indication which depends on the present load mode to provide confirmation The units used are A V W OHM SIE HZ SIE ...

Page 46: ...or off where NRF has the meaning 0 Off 1 On SLOW Returns the setting of the Slow Start facility The response is SLOW NR1 RMT where NR1 is either 0 Off or 1 On LVLSEL CPD Set the Active Level Select to CPD Where CPD can be A B T V or E corresponding to Level A Level B Transient Ext Voltage and Ext TTL LVLSEL Returns the Level Select state The response is LVLSEL CRD RMT Where CRD can be A B T V or E...

Page 47: ...ion error OPC Sets the Operation Complete bit bit 0 in the Standard Event Status Register This will happen immediately the command is executed because of the sequential nature of all operations OPC Query Operation Complete status The response is always 1 RMT and is available immediately the command is executed because all commands are sequential WAI Wait for Operation Complete true This command do...

Page 48: ...e web interface ADDRESS Returns the GPIB bus Address The response is NR1 RMT IPADDR Returns the present IP address of the LAN interface provided it is connected If it is not connected the response will be the static IP if configured to always use that static IP otherwise it will be 0 0 0 0 if waiting for DHCP or Auto IP The response is nnn nnn nnn nnn RMT where each nnn is 0 to 255 NETMASK Returns...

Page 49: ...thin specification the calibration must be checked and if necessary adjusted annually The procedure is detailed in the Service Guide which also lists the calibrated test equipment required Firmware Update The firmware of the instrument can be updated through the USB port using a PC software utility available from the manufacturer This uses a HID human interface device USB class driver which will a...

Page 50: ...ominale recommandées ni hors de ses tolérances d environnement AVERTISSEMENT CET INSTRUMENT DOIT ÊTRE RELIÉ À LA TERRE Toute interruption du conducteur de terre du secteur à l intérieur ou à l extérieur de l instrument rendra l instrument dangereux Une interruption intentionnelle est interdite La sécurité de l instrument ne doit pas être annulée par l utilisation de rallonge sans conducteur de pro...

Page 51: ...bungsbedingungen betreiben ACHTUNG DIESES GERÄT MUSS GEERDET WERDEN Jegliche Unterbrechung der Netzerde ob im Innern oder außerhalb des Geräts macht das Gerät zur Gefahrenquelle Eine absichtliche Unterbrechung ist verboten Die Schutzwirkung darf durch Verwendung eines Verlängerungskabels ohne Schutzleiter nicht aufgehoben werden Ist das Gerät an die elektrische Versorgung angeschlossen können die ...

Page 52: ...ZA LO STRUMENTO DEVE ESSERE PROVVISTO DI MESSA A TERRA L interruzione della messa a terra all interno o all esterno dello strumento ne rende pericoloso l utilizzo L interruzione intenzionale della messa a terra è severamente vietata L azione protettiva della messa a terra non deve essere annullata dall utilizzo di una prolunga priva di conduttore di protezione Quando lo strumento è collegato all a...

Page 53: ...ado ADVERTENCIA ESTE INSTRUMENTO DEBE CONECTARSE A TIERRA Cualquier interrupción del conductor de puesta a tierra dentro o fuera del instrumento hará que este resulte peligroso Está prohibida la interrupción intencionada No se debe inhibir este mecanismo de protección mediante un alargador que no tenga conductor de toma de tierra Cuando el instrumento esté conectado a la fuente de alimentación pue...

Page 54: ...Book Part No 48511 1730 Issue 2 ...

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