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SECTION 7. MEASUREMENT PROGRAMMING EXAMPLES

7-9

The advantages of the 3 wire half bridge are
that it only requires 3 lead wires going to the
sensor, and takes 2 single ended input
channels whereas the 4 wire half bridge
requires 2 differential input channels.

PROGRAM

01:

P

7

3 Wire Half Bridge

01:

1

Rep

02:

4

50 mV slow Range

03:

1

IN Card

04:

1

IN Chan

05:

1

EX Card

06:

1

EX Chan

07:

1

Meas/EX

08: 4300

mV Excitation

09:

1

Loc [:Rs/Ro ]

10:

100.93

Mult

11:

0

Offset

02:

P

16 Temperature RTD

01:

1

Rep

02:

1

R/Ro Loc Rs/Ro

03:

2

Loc [:TEMP degC]

04:

1

Mult

05:

0

Offset

7.13 100 OHM PRT IN 4 WIRE FULL

BRIDGE

This example describes obtaining the
temperature from a 100 ohm PRT in a 4 wire
full bridge (Instruction 6). The temperature
being measured is in a constant temperature
bath and is to be used as the input for a control
algorithm. The PRT in this case does not
adhere to the DIN standard (alpha = 0.00385)
used in the temperature calculating Instruction
16. Alpha is defined as (R100/R0-1)/100 where

R100 and R0 are the resistances of the PRT at

100 oC and 0 oC, respectively. In this PRT
alpha is equal to 0.00392.

FIGURE 7.13-1. Full Bridge Schematic For

100 Ohm PRT

The result given by Instruction 6 (X) is 1000
Vs/Vx (where Vs is the measured bridge output

voltage and Vx is the excitation voltage) which

is:

X = 1000 (Rs/(Rs+R1)-R3/(R2+R3))

The resistance of the PRT (Rs) is calculated

with the Bridge Transform Instruction 59:

Rs = R1 X'/(1-X')

Where

X' = X/1000 + R3/(R2+R3)

Thus, to obtain the value Rs/R0, (R0 = Rs @

0oC) for the temperature calculating Instruction
16, the multiplier and offset used in Instruction 6
are 0.001 and R3/(R2+R3), respectively. The

multiplier used in Instruction 59 to obtain Rs/R0

is R1/R0 (5000/100 = 50).

It is desired to control the temperature bath at
50oC with as little variation as possible. High
resolution is desired so the control algorithm will
be able to respond to minute changes in
temperature. The highest resolution is obtained
when the temperature range results in an output
voltage (Vs) range which fills the measurement

range selected in Instruction 6. The full bridge
configuration allows the bridge to be balanced
(Vs = 0V) at or near the control temperature.

Thus, the output voltage can go both positive
and negative as the bath temperature changes,
allowing the full use of the measurement range.

The resistance of the PRT is approximately
119.6 ohms at 50 oC. The 120 ohm fixed
resistor balances the bridge at approximately 51

oC. The output voltage is:

Vs = Vx [Rs/(Rs+R1) - R3/(R2+R3)]

= Vx [Rs/(Rs+5000) - 0.023438]

The temperature range to be covered is 50
+5oC. At 45 oC Rs is approximately 117.6

ohms, or:

Vs = -458.448x10-6 Vx

Vs can be measured on the ±1500 µV scale.

Setting Vs equal to -1500 µV and solving for Vx

results in Vx = 3.272 V. Vx is entered as 3270

mV in Parameter 8 of Instruction 6.

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Содержание CR7

Страница 1: ...CR7 MEASUREMENT AND CONTROL SYSTEM INSTRUCTION MANUAL REVISION 7 97 COPYRIGHT c 1991 1997 CAMPBELL SCIENTIFIC INC ...

Страница 2: ...This is a blank page ...

Страница 3: ...erchantability or fitness for a particular purpose CAMPBELL SCIENTIFIC INC is not liable for special indirect incidental or consequential damages Products may not be returned without prior authorization To obtain a Returned Materials Authorization RMA contact CAMPBELL SCIENTIFIC INC phone 435 753 2342 After an applications engineer determines the nature of the problem an RMA number will be issued ...

Страница 4: ...This is a blank page ...

Страница 5: ...OV2 1 Internal Memory OV 3 OV2 2 CR7 Instruction Types OV 6 OV2 3 Program Tables and the Execution and Output Intervals OV 6 OV3 PROGRAMMING THE CR7 OV3 1 Functional Modes OV 8 OV3 2 Key Definition OV 8 OV3 3 Programming Sequence OV 8 OV3 4 Instruction Format OV 9 OV3 5 Entering a Program OV 9 OV4 PROGRAMMING EXAMPLE OV4 1 Measurement OV 10 OV4 2 Output OV 12 OV4 3 Editing an Existing Program OV 1...

Страница 6: ...1 3 3 Entering Negative Numbers 3 1 3 4 Indexing Input Locations 3 2 3 5 Voltage Range and Overrange Detection 3 2 3 6 Output Processing 3 2 3 7 Use of Flags Output and Program Control 3 3 3 8 Program Control Logical Constructions 3 4 3 9 Instruction Memory and Execution Time 3 6 3 10 Error Codes 3 9 DATA RETRIEVAL COMMUNICATION 4 EXTERNAL STORAGE PERIPHERALS 4 1 On Line Data Transfer Instruction ...

Страница 7: ...oad Cell 7 11 7 16 227 Gypsum Soil Moisture Block 7 13 7 17 Nonlinear Thermistor in Half Bridge CSI Model 101 7 14 8 PROCESSING AND PROGRAM CONTROL EXAMPLES 8 1 Computation of Running Average 8 1 8 2 Rainfall Intensity 8 2 8 3 SUB 1 Minute Output Interval Synched to Real Time 8 3 8 4 Analog Output to Strip Chart 8 4 8 5 Converting 0 360 Wind Direction Output to 0 540 for Strip Chart 8 5 8 6 Covari...

Страница 8: ...ESSING AND MULTIPLE I 0 MODULES 15 1 I O Card Identification Number Decoding 15 1 15 2 Use of Multiple I O Modules 15 4 APPENDICES A GLOSSARY A 1 B CR7 PROM SIGNATURES FOR SYSTEMS EQUIPPED WITH STANDARD SOFTWARE B 1 C BINARY TELECOMMUNICATIONS C 1 Telecommunications Command With Binary Responses C 1 C 2 Final Storage Format C 3 C 3 Generation of Signature C 4 D CALIBRATION PROCEDURES D 1 Voltage R...

Страница 9: ...aracters but the default case for all data stored in Final Memory is LOW RESOLUTION unless high resolution is specified through use of Instruction 78 Floating Point Format The computations performed in the CR7 use floating point arithmetic CSI s 4 byte floating point numbers contain a 23 bit binary mantissa and a 6 bit binary exponent The largest and smallest numbers that can be stored and process...

Страница 10: ... power switch is off Reverse polarity protection is NOT provided on this connection so exercise extreme care if connecting external power supplies Damage will occur to the analog input channel circuitry if voltages in excess of 16V are applied for a sustained period A POTENTIALLY DANGEROUS situation can result due to hydrogen gas build up if the CR7 is housed in a gas tight enclosure and the inter...

Страница 11: ...onsulting the manual if further detail is needed Read the Selected Operating Details and Cautionary Notes at the front of the Manual before using the CR7 OV1 PHYSICAL DESCRIPTION The CR7 features a modular multiple processor design that provides precision measurement and control capability in a rugged battery operated system Control Module functions include real time task initiation measurement pr...

Страница 12: ...ect to the voltage on the Low input When making single ended measurements either the HI or the Low channel may be used independently to measure the voltage with respect to the CR7 ground Single ended channels are numbered sequentially e g the HI and LOW sides of differential channels 2 are single ended channels 3 and 4 respectively Section 13 2 724 PULSE COUNTER CARD Provides 4 pulse counting chan...

Страница 13: ...ate and may range from samples every execution interval to processed summaries output hourly daily or on longer or irregular intervals Figure OV2 1 represents the measurement processing and data storage sequence in the CR7 and shows the types of instructions used to accomplish these tasks OV2 1 INTERNAL MEMORY The CR7 has 40 960 bytes of Random Access Memory RAM divided into five areas The five ar...

Страница 14: ...ALOG IPUTS Input Output Instructions 1 Volt SE 2 Volt DIFF 4 Ex Del Se 5 AC Half Br 6 Full Br 7 3W Half Br 9 Full Br Mex 11 Temp 107 12 RH 07 13 Temp TC SE 14 Temp TC DIFF 17 Temp Panel SDM PORTS 101 SDM INT8 102 SDM SW8 103 SDM AO4 104 SDM CD16 113 SDM SIO4 115 Set SDM Clock 118 SDM OBDII CS I O PORT Telecommunications Program Control Instructions 96 Storage Module Printer 97 Initiate Telecommuni...

Страница 15: ... the values updated in Input Storage Summaries for Final Storage are generated when a Program Control Instruction sets the Output Flag in response to time or events Results may be redirected to Input Storage for further processing Examples include sums averages max min standard deviation histograms etc Output Flag set high FINAL STORAGE Final results from OUTPUT PROCESSING INSTRUCTIONS are stored ...

Страница 16: ...ed to develop high level algorithms to process measurements prior to Output Processing Section 10 3 OUTPUT PROCESSING INSTRUCTIONS 69 82 Section 11 are the only instructions which store data in Final Storage destination Input Storage source values are processed over time to obtain averages maxima minima etc There are two types of processing done by Output Instructions Intermediate and Final Interm...

Страница 17: ...able and waits for the next execution interval before initiating the table When an overrun occurs decimal points are shown on either side of the G on the display in the LOG mode 0 Overruns and table priority are discussed in Section 1 1 OV2 3 2 THE OUTPUT INTERVAL The interval at which output occurs is independent from the execution interval other than the fact that it must occur when the table is...

Страница 18: ...nto display Enter Mode followed by Mode Number A Enter Advance B Back up C Change the sign of a number or index an input location to loop counter D Enter the decimal point Clear the rightmost digit keyed into the display A Advance to next instruction in program table 1 2 3 or to next output array in Final Storage 7 B Back up to previous instruction in program table or to previous output array in F...

Страница 19: ...G A PROGRAM Programs are entered into the CR7 in one of four ways 1 Keyed in using the CR7 keyboard 2 Loaded from a pre recorded listing using the D Mode There are two types of storage input a Stored on disk sent from computer PC208 software b Stored loaded from SM192 716 Storage Module 3 Loaded from Storage Module or internal PROM special software upon power up A program is created by keying it d...

Страница 20: ... differential channel and the constantan lead is connected to the low side The channel numbering printed on the Analog Input Cards refers only to differential channels Either the high or low side of a differential channel may be used for single ended measurements Each side is counted when assigning single ended channel numbers e g the high side of differential channel 8 is single ended channel 15 ...

Страница 21: ... Location Number will be 1 less i e 01 P00 02 P00 01 00 02 00 03 00 04 00 05 00 06 0000 07 0000 08 0 0000 09 0 0000 03 P00 00 00 14 1 2 1 5 1 1 2 1 0 02 P14 01 1 02 2 03 1 04 5 05 1 06 1 07 2 08 1 09 0 0000 LOG 1 A A A A A A A A A A TC temp differential meas 1 repetition Range code 5000uV slow Input card 1 Input channel of 1st TC TC type copper constantan Reference temp is in location 1 Store TC t...

Страница 22: ...temp is 2 9533 C backup to location 1 Setup to change stored value Store 20 in location 1 Advance to location 2 The TC temp in location 2 using a reference temperature of 20o Return to 0 Mode You can advance through Input Storage by keying in the advance command A or backup by keying in the backup command B The Input Location you are observing is shown on the left in the display ID field The tempe...

Страница 23: ...raged Exit Table 1 Enter 5 Mode to set clock the clock will be running Enter Year Enter Julian day January 11 assumed in this example Enter Hours Minutes 24 hour time 1 24 PM assumed in this example Exit 5 Mode compile Table 1 commence logging data The CR7 is now programmed to sample the panel and thermocouple temperatures every 2 seconds and to output the time and the average temperatures to Fina...

Страница 24: ...he new instruction will be inserted at that point in the table advance through and enter the parameters The Instruction that was at that point and all instructions following it will be pushed down to follow the inserted instruction An instruction is deleted by advancing to the instruction number P in display and keying D Table OV3 2 To change the value entered for a parameter advance to parameter ...

Страница 25: ...ted in Final Storage since the last visit 3 Retrieve the data over some form of telecommunications link that is Radio Frequency RF telephone short haul modem multi drop interface or satellite The PC208 software automates this process Regardless of which method is used the retrieval of data from the datalogger does NOT erase those data from Final Storage The data remain in the ring memory until the...

Страница 26: ...STEM 700X CONTROL MODULE SERIAL I O CAMPBELL SCIENTIFIC INC LOGAN UTAH H H H H 1 2 3 4 724 PULSE COUNTER H L H L H L H L H L H L H L H L H L H L H L H L H L H L 1 2 3 4 5 6 7 8 9 10 11 12 13 14 1 2 3 4 5 6 7 8 1 2 SWITCHED ANALOG OUT CONTINUOUS ANALOG OUT 1 2 3 4 5 6 7 8 DIGITAL CONTROL OUT 725 EXCITATION H 726 50 VOLT INPUT L 1 H L 2 H L 3 H L 4 H L 5 H L 6 H L 7 H L 8 SOLAR TEMP C RH 1 2 3 Scale...

Страница 27: ... then switches off high impedance Only one switched output can be active at a time Continuous A preset voltage is held until updated Voltage degrades 0 17 mV every 7 seconds All continuous analog outputs and digital control ports can be active simultane ously Range 5 V Resolution 166 µV Accuracy Same as voltage measurements Output Current 25 mA at 5 V 50 mA at 2 V Resistance and Conductivity Measu...

Страница 28: ...CR7 MEASUREMENT AND CONTROL SYSTEM OVERVIEW OV 18 This is a blank page ...

Страница 29: ...by the instruction initiating the measurement The next instruction in the table is not executed until the scaling is completed The maximum sample rate for a measurement is the rate at which the I O Module can make a number of measurements specified by a single input instruction Because the sample rate does not include the processing time required to scale the measurements into engineer units the e...

Страница 30: ...rage to ZERO When the 6 Mode is used to compile data in Input Storage the state of flags control ports and the timer are UNALTERED Compiling always zeros Intermediate Storage 1 2 SETTING AND DISPLAYING THE CLOCK 5 MODE The 5 Mode is used to display time or change the year day of year or time When 5 is pressed the current time is displayed The time parameters displayed in the 5 Mode are given in Ta...

Страница 31: ... high to enable the table s If any program tables 1 2 3 or 4 output options are altered and complied in the 0 Mode values in Input Storage will be set to 0 To preserve values entered in Input Storage compile with 6 1 3 2 DISPLAYING AND TOGGLING USER FLAGS If D is keyed while the CR7 is displaying a location value the current status of the user flags will be displayed in the following format 00 01 ...

Страница 32: ...e present can be determined with the A Mode Section 2 4 2 There are 1744 bytes allotted to program memory This memory may be used for one program table or shared among all program tables Tables 3 9 1 to 3 9 4 list the amount of memory used by each program instruction Input Storage is used to store the results of Input Output and Processing Instructions The values stored in input locations may be d...

Страница 33: ...ying A The size of Final Storage will be adjusted automatically One input or Intermediate Storage location can be exchanged for two Final Storage locations and vice versa Input and Intermediate Storage must reside in the CPU board RAM If additional memory boards are present it is possible to use all of the CPU board RAM for Input and Intermediate Storage A minimum 32 Input and 768 Final Storage lo...

Страница 34: ...gnature A 05 XXXXX Memory status No K RAM and ROM A 06 XXXXX No of E08 occurrences Key in 88 to reset A 07 XXXXX No of overrun occurrences Key in 88 to reset A 08 X XXXX PROM version number A 09 XXXX Version revision number A 01 00 Enter I O Module No to test usually 1 1A 01 XXXXX I O Module 1 RAM Signature 01 XXXXX I O Module 1 PROM Signature 1 7 C MODE SECURITY The C Mode is used to secure the u...

Страница 35: ...er outputs are suspended while in the D Mode When D is keyed the CR7 will display 13 00 TABLE 1 8 1 D Mode Commands Command Description 1 Save ASCII Program 2 Load ASCII Program 71 Save Load Clear Program from Storage Module A command is entered by keying the command number and A When Command 1 2 or 71 is entered the command number is displayed in the ID field The user must then key in a baud rate...

Страница 36: ...UTER PRINTER This section describes commands 1 and 2 Table 1 8 1 The PC208 Software automatically uses these commands for uploading and downloading programs SENDING ASCII PROGRAM INFORMATION Command 1 is to send the program listing in ASCII At the end of the listing the CR7 sends control E 5 hex or decimal twice Except when in telecommunications the baud rate code must be entered after command 1 T...

Страница 37: ...ure for current buffer D D 4hex 4hex Load current buffer and reset signature E E 5hex 5hex Exit and compile program As a download file is received the CR7 buffers the data in memory the data is not loaded into the editor or compiled until the CR7 receives a command to do so The minimum file that could be sent is the program listing then E E C C tells the CR7 to send the signature Section C 3 for t...

Страница 38: ...SECTION 1 FUNCTIONAL MODES 1 10 This is a blank page ...

Страница 39: ...Output Array ID This ID number is set in one of two ways 1 In the default condition the ID consists of the program table number and the Instruction Location Number of the instruction which set the Output Flag for that output array For example the ID of 118 in Figure 2 1 2 indicates that the 18th instruction in Table 1 set the Output Flag high FIGURE 2 1 2 Output Array ID 2 The output array ID can ...

Страница 40: ...the external calling device Section 5 1 NOTE All memory pointers are set to the DSP location when the datalogger compiles a program For this reason ALWAYS RETRIEVE UNCOLLECTED DATA BEFORE MAKING PROGRAM CHANGES 2 2 DATA OUTPUT FORMAT AND RANGE LIMITS Data are stored internally in Campbell Scientific s Final Storage Format Appendix C 2 Data may be sent to Final Storage in either LOW RESOLUTION or H...

Страница 41: ...oint format may be found in the description of the J and K telecommunications commands in Appendix C 2 3 DISPLAYING STORED DATA ON KEYBOARD DISPLAY 7 MODE The 7 Mode is used to display Final Storage data Enter the Mode by keying 7 The display will show 07 XXXXX where XXXXX is the Final Storage location DSP where the next data will be stored Two options are available 1 Press A to advance and displa...

Страница 42: ...SECTION 2 INTERNAL DATA STORAGE 2 4 This is a blank page ...

Страница 43: ...ing Instructions is used to repeat the instruction on a number of sequential Input Channels or Input Storage locations Separate parameters are used to specify the card and input channel on which to make the first measurement For example if you have four differential voltage measurements to make on the same voltage range wire the inputs to sequential channels and instead of entering the Differentia...

Страница 44: ...z AC line power as well as having better rejection of random noise than the fast integration A PROM with 50Hz rejection is available for countries whose electric utilities operate at 50 Hz Appendix B When a voltage input exceeds the range programmed the value stored is the maximum negative number displayed in the 6 Mode as 99999 In output data from Final Storage this becomes 6999 in low resolution...

Страница 45: ...changed until acted on by a Program Control Instruction or until manually toggled from the 6 Mode TABLE 3 7 1 Flag Description Flag 0 Output Flag Flag 1 to 8 User Flags Flag 9 Intermediate Processing Disable Flag Flags are set with Program Control Instructions The Output Flag Flag 0 and the intermediate processing disable flag Flag 9 will always be set low if the set high condition is not met The ...

Страница 46: ...6 Do 1 29 Set Flag 9 Low NOTE Flag 9 is automatically reset the same as Flag 0 If the intermediate processing disable flag is already set high and the test condition of a subsequent Program Control Instruction acting on Flag 9 fails the flag is set low This feature eliminates having to enter another instruction to specifically reset Flag 9 before proceeding to another group of test conditions 3 7 ...

Страница 47: ...in Case Instruction 93 and If Case Instruction 83 allow a series of tests on the value in an input location The case test is started with Instruction 93 which specifies the location to test A series of Instructions 83 are then used to compare the value in the location with fixed values When the value in the input location is less than the fixed value specified in Instruction 83 the command in that...

Страница 48: ...oups of nested instructions may be used in any of the three Programming Tables The number of groups is only restricted by the program memory available 3 9 INSTRUCTION MEMORY AND EXECUTION TIME The standard CR7 has 1744 bytes of program memory available for the programs entered in the 1 2 and 3 program tables Each instruction also makes use of varying numbers of Input Intermediate and Final Storage...

Страница 49: ... Z EXP X 1 0 6 5 9 42 Z 1 X 1 0 6 2 6 43 Z ABS X 1 0 6 0 7 44 Z FRAC X 1 0 6 0 3 45 Z INT X 1 0 6 1 0 46 Z X MOD F 1 0 10 3 2 47 Z XY 1 0 8 13 3 48 Z SIN X 1 0 6 6 5 49 SPA MAX 1 or 2 0 7 1 5 0 9 swath 1 50 SPA MIN 1 or 2 0 7 1 7 0 9 swath 1 51 SPA AVG 1 0 7 3 3 0 6 swath 1 53 A X B 4 0 36 2 5 0 4 scaling pair 54 BLOCK MOVE R 0 10 0 18 0 17R 55 POLYNOMIAL R 0 31 1 2 R 2 0 0 4 order 56 SAT VP 1 0 6...

Страница 50: ...r3 R 8 0 9 1 7R 1 3 2 8R 75 HISTOGRAM 1 bins R bins R 24 0 4 3 1R 0 9 R 3 3 2 8 bins 77 REAL TIME 0 1 to 4 4 0 1 1 0 78 RESOLUTION 0 0 3 0 4 0 4 79 SMPL ON MM R R 7 0 3 1 1 80 STORE AREA 0 0 5 82 STD DEV 1 3R R 7 1Output values may be sent to either Final Storage or Input Storage with Instruction 80 TABLE 3 9 4 Program Control Instruction Memory and Execution Times INSTRUCTION MEMORY EXECUTION TIM...

Страница 51: ...to 99 that E08 has occurred The number can be displayed and reset with the Telecommunications A command Section 5 1 Editor errors are detected as soon as an incorrect value is entered and are displayed immediately D Mode errors indicate problems with saving or loading a program Only the error code is displayed TABLE 3 10 1 Error Codes Code Type Description 01 Run Time I O Module does not respond 0...

Страница 52: ...SECTION 3 INSTRUCTION SET BASICS 3 10 This is a blank page ...

Страница 53: ...s present When Instruction 96 or 9 is used to send data to one of these Storage Modules the CR7 will not send data if the Storage Module is not connected Section 4 4 2 4 1 ON LINE DATA TRANSFER INSTRUCTION 96 4 MODE On line data transfer is accomplished with Instruction 96 entered in the datalogger program The 4 Mode is retained from earlier software to maintain compatibility with existing program...

Страница 54: ...able time between visiting the site to retrieve data must be calculated to insure that data placed in Final Storage are not written over before they are collected In order to make this calculation users must determine 1 the size of Final Storage 2 the number of output arrays being generated 3 the number of low and or high resolution data points included in each output array and 4 the rate at which...

Страница 55: ...ed to the Storage Module a File Mark is placed in the data if a File Mark is not the last data point already in storage The File Mark separates data For example if you retrieve data from one CR7 disconnect the Storage Module and connect it to a second CR7 a File Mark is placed in the data This mark follows the data from the first CR7 but precedes the data from the second The SM192 has 192K bytes o...

Страница 56: ... is as follows 1 Connect the Storage Module to the CR7 using the SC12 cable 2 Enter the appropriate commands as listed in Table 4 2 2 4 4 PRINTER OUTPUT FORMATS Printer output can be sent in the binary Final Storage Format Appendix C 2 or Printable ASCII If using the 4 Mode to enable on line output Printable ASCII is the only format available In the Printable ASCII format each data point is preced...

Страница 57: ...SECTION 4 EXTERNAL STORAGE PERIPHERALS 4 5 FIGURE 4 4 1 Example of CR7 Printable ASCII Output Format ...

Страница 58: ...SECTION 4 EXTERNAL STORAGE PERIPHERALS 4 6 This is a blank page ...

Страница 59: ...data retrieval program transfer and real time monitoring The PC208 package has been designed to meet the most common needs in datalogger support and telecommunications This section in not intended to furnish sufficient detail to write Telecommunications software Appendix C contains some details of binary data transfer and Campbell Scientific s binary data format This section emphasizes the command...

Страница 60: ...munication after receiving 150 invalid characters The CR7 continues to execute its measurement and processing tasks while servicing the telecommunication requests If the processing overhead is large short execution interval the processing tasks will slow the telecommunication functions In a worst case situation the CR7 interrupts the processing tasks to transmit a data point every 0 1 second The b...

Страница 61: ...pendix C for details K CURRENT INFORMATION In response to the K command the CR7 sends datalogger time user flag status the data at the input locations requested in the J command and Final Storage Data if requested by the J command Used in the Monitor Mode and with Heads Up Display See Appendix C Password L Unlocks security if enabled to the level determined by the password entered See C Mode Secti...

Страница 62: ...ram changes have been made To compile and run the program without leaving the Remote Keyboard State use 6 Section 1 1 4 The CR7 display will show LOG when 0 is executed via telecommunications It will not indicate active tables enter 0 via the keyboard and the display will show the tables 2718H Telecommunications Remote Command 0 Keyboard State State ...

Страница 63: ...Provides a power return for pin 1 5V and is used as a reference for voltage levels 3 RING I Ring When raised by a peripheral the CR7 enters telecommunications 4 RXD I Receive Data Serial data transmitted by a peripheral are received on pin 4 5 ME O Modem Enable Raised by the CR7 after the ring line has been raised PIN ABR I O Description 6 PE O Printer Enable Raised to enable Storage Module or oth...

Страница 64: ... If the key is pressed during data transfer the transfer is stopped and the display shows the Final Storage location where the pointer stopped Data transfer can be stopped as follows 1 Printable ASCII after every output array 2 Binary after every Final Storage location 6 4 TELECOMMUNICATIONS MODEM PERIPHERALS Any serial communication device which raises the Ring line and holds it high until the ME...

Страница 65: ...ich are set high when the serial port is enabled Power for the SC32A is taken from these pins For equipment configured as DTE a direct ribbon cable connects the modem terminal to the SC32A Clear to Send CTS pin 5 Data Set Ready DSR pin 6 and Received Line Signal Detect RLSD pin 8 are held high by the SC32A when the RS232 section is powered which should satisfy hardware handshake requirements of th...

Страница 66: ...t data bit and a Stop bit is sent after the eighth data bit The start bit is always a space and the stop bit is always a mark Between characters the signal is in the marking condition Figure 6 5 1 shows how the ASCII character 1 is transmitted The SC32A interface transmits spacing and marking voltages which are positive and negative as shown Signal voltages at the CR7 I O port are 5 volts in the s...

Страница 67: ... match with Table 6 5 1 If you are using a computer without the PC208 software then a program or communication software must be used to enable the serial port and to make the computer function as a terminal The port should be enabled for 300 1200 or 9600 baud 8 data bits 1 stop bit and no parity If you are not sure that your computer or terminal is sending or receiving characters there is a simple...

Страница 68: ...SECTION 6 9 PIN SERIAL INPUT OUTPUT 6 6 This is a blank page ...

Страница 69: ... ohm resistor The calibration supplied by LI COR the manufacturers of the pyranometer is given in uA kW m2 The calibration in terms of volts is determined by multiplying the µA calibration by the resistance of the fixed resistor The calibration of the pyranometer used in this example is assumed to be 76 9 µA kW m2 which when multiplied by 100 ohms equals 7 69 mV kW m2 The multiplier used to conver...

Страница 70: ... be corrected in programming the CR7 However it is better to use a differential voltage measurement which does not rely on the current drain remaining constant The Program that follows illustrates the use of Instruction 2 to make the measurement A multiplier of 0 014 is used to convert the millivolt output into pH units PROGRAM 01 P2 Volt DIFF 01 1 Rep 02 7 1500 mV slow Range 03 1 IN Card 04 1 IN ...

Страница 71: ...A single ended TC measurement 13 of R temperatures to be used as reference temperatures for the measurement D 3 A differential TC measurement of D temperatures where the reference temperature at R are subtracted from the results as specified in Parameter 5 The connection shown in Figure 7 4 1 yields the conventional polarity sign for the temperature difference i e D R T D R T Using R as the refere...

Страница 72: ...ature difference before the reference temperature is added Example A demonstrates the use of a scaling array Instruction 53 to correct the calibration of four individually calibrated thermocouples Another means of applying a correction factor to a number of thermocouples is to group together those with a similar correction factor In example B the slope correction factor for a group of 5 thermocoup...

Страница 73: ...nnel 1 and high side of 2 PROGRAM 01 P11 Temp 107 Probe 01 3 Reps 02 1 IN Card 03 1 IN Chan 04 1 EX Card 05 1 EX Chan 06 1 Loc 107 T 1 07 1 Mult 08 0 Offset 7 8 207 TEMPERATURE AND RH PROBE Instruction 12 excites and measures the RH portion of the Campbell Scientific 207 temperature and relative humidity probe This instruction relies on a previously measured temperature to compute the RH from the ...

Страница 74: ... second The manufacturer s calibration for relating wind speed to rpm is Wind speed m s 0 01632 m s rpm x rpm 0 2 m s The multiplier and offset to convert pulses per second to meters per second are m s 0 01632 m s rpm x 6 rpm pulse s 0 2 m s 0 0979 m s pulse x pulses 0 2 m s There are occasionally times when the CR7 s CPU is occupied and does not reset the pulse counters at the exact time interval...

Страница 75: ...the PRT can be made on the same range as the differential measurement of the voltage drop across Rf The use of the same range eliminates any range translation error that might arise from the 0 01 tolerance of the range translation resistors in the CR7 If the voltage drop across the PRT V2 is kept on the 50 mV range self heating of the PRT should be less than 0 001 oC in still air The resolution of...

Страница 76: ...Figure 7 12 1 Figure 7 12 1 3 Wire Half Bridge Used to Measure 100 ohm PRT As in the example in section 7 11 the excitation voltage is calculated to be the maximum possible yet allow the 50 mV measurement range The 10 kohm resistor has a tolerance of 1 thus the lowest resistance to expect from it is 9 9 kohms We calculate the maximum excitation voltage Vx to keep the voltage drop across the PRT le...

Страница 77: ...h is X 1000 Rs Rs R1 R3 R2 R3 The resistance of the PRT Rs is calculated with the Bridge Transform Instruction 59 Rs R1 X 1 X Where X X 1000 R3 R2 R3 Thus to obtain the value Rs R0 R0 Rs 0oC for the temperature calculating Instruction 16 the multiplier and offset used in Instruction 6 are 0 001 and R3 R2 R3 respectively The multiplier used in Instruction 59 to obtain Rs R0 is R1 R0 5000 100 50 It ...

Страница 78: ...ement made with a Druck PDCR 10 D depth measurement pressure transducer The pressure transducer was ordered for use with 5 volt positive or negative excitation passive temperature compensation and has a range of 5 psi or about 3 5 meters of water The transducer is used to measure the depth of water in a stilling well Instruction 6 4 wire full bridge is used to measure the pressure transducer The h...

Страница 79: ...epresents a maximum change of 909 kg or 28 cm of water in the lysimeter before the counterbalance would have to be readjusted FIGURE 7 15 1 Diagrammatic Representation of Lysimeter Weighing Mechanism There is 1000 feet of 22 AWG cable between the CR7 and the load cell The output of the load cell is directly proportional to the excitation voltage When Instruction 6 4 wire 1 2 bridge is used the ass...

Страница 80: ...s of the lysimeter increases if the actual mechanical linkage was as diagrammed in Figure 7 15 1 the output voltage would be positive when the load cell was under tension When the experiment is started the water content of the soil in the lysimeter is approximately 25 on a volume basis It is decided to use this as the reference i e 0 25 x 1500mm 375 mm The experiment is started at the beginning of...

Страница 81: ...000s of ohms The multiplier is a scaling factor to maintain the maximum number of significant digits in the coefficients of the polynomial In this example we wish to make measurements on 12 gypsum blocks and output the final data in bars The soil where the moisture measurements are to be made is quite wet at the time the data logging is initiated but is expected to dry beyond the 2 bar limit of th...

Страница 82: ...livolts to temperature E denotes the power of 10 by which the mantissa is multiplied C0 53 7842 C1 0 147974 C2 2 18755E 4 C3 2 19046E 7 C4 1 11341E 10 C5 2 33651E 14 The CR7 will only allow 5 significant digits to the right or left of the decimal point to be entered from the key board The polynomial can not be applied exactly as given in the 101 manual The initial millivolt reading must be scaled ...

Страница 83: ...or computing a running average In this example each time a new measurement is made in this case a thermocouple temperature an average is computed for the 10 most recent samples This is done by saving all 10 temperatures in contiguous input locations and using the Spatial Average Instruction 51 to compute the average The temperatures are stored in locations 11 through 20 Each time the table is exec...

Страница 84: ...and again to send the three hour average to Final Storage Input Location Labels 1 AVG i 2 2 AVG i 1 3 AVG i 4 3 HR AVG 5 XX mg M3 1 Table 1 Programs 01 5 Sec Execution Interval 01 P2 Volt DIFF 01 1 Rep 02 8 5000 mV slow Range 03 1 IN Card 04 3 IN Chan 05 3 Loc XX mg m3 06 10 Mult 07 0 Offset 02 P92 If time is 01 0 minutes into a 02 60 minute interval 03 10 Set high Flag 0 output 03 P80 Set Active ...

Страница 85: ...al one gets a counter in an input location that goes to 0 on a periodic interval In this example tenths of seconds into the minute is modulo divided by 300 The counter counts up to 295 then goes to 0 i e every 30 seconds tenths of seconds into minute has a resolution of 0 1 seconds Instruction 89 is used to set the Output Flag when the tenths of seconds counter is less than 5 the execution interva...

Страница 86: ...ckup on weather data Instruction 21 may be used with the CR7 to provide two continuous analog outputs for strip charts The output values in this example are wind speed and wind direction The following program measures the sensors every five seconds The readings are moved to another two locations and scaled to a 0 to 1000 millivolt output for the strip chart Wind direction is changed from a 0 360 d...

Страница 87: ... out of the north or south When faced with the necessity of strip chart output see previous example the following algorithm can be used to change a 0 360 degree input to 0 540 If you have a 0 540 pot it can be used with the 21X since the Wind Vector Instruction 69 will work with this output To change 0 360 degrees to the 0 540 degrees 360 degrees must sometimes be added to the reading when it is i...

Страница 88: ...all be measured as single ended voltages but the vertical wind prop calibration differs from the U and V prop calibration The fastest input sequence is to measure both levels 6 props with a single instruction using the U and V calibration and correct the W measurements with the Fixed Multiply Instruction 37 The type E thermocouples are measured on the most sensitive input range 5mV accommodating a...

Страница 89: ...fying the destination location in the Wet Dry Bulb Instruction The CV CR Instruction must be entered twice once for each level In addition to ordering Level 1 and Level 2 in locations 1 5 and 11 15 respectively two more locations are required Converting the wet dry bulb measurements to vapor pressure using Instruction 57 requires atmospheric pressure We ll use the standard atmosphere for the site ...

Страница 90: ...c W2 08 P57 Wet Dry Bulb Temp to VP 01 17 Pressure Loc 02 9 Dry Bulb Temp Loc 03 10 Wet Bulb Temp Loc 04 5 Loc U2 09 P57 Wet Dry Bulb Temp to VP 01 17 Pressure Loc 02 14 Dry Bulb Temp Loc 03 15 Wet Bulb Temp Loc Tw2 04 15 Loc Tw2 10 P92 If time is 01 0 minutes into a 02 30 minute interval 03 10 Set high Flag 0 output 11 P62 CV CR 01 5 No of Input Values 02 5 No of Means 03 5 No of Variances 04 0 N...

Страница 91: ...s cannot be used to advance from one 726 card to the next When a voltage input exceeds the range programmed the value which is stored is set to the maximum negative number displayed as 99999 in high resolution or 6999 in low resolution 1 SINGLE ENDED VOLTS FUNCTION This instruction is used to measure voltage at a single ended input with respect to ground PAR DATA NO TYPE DESCRIPTION 01 2 Repetitio...

Страница 92: ...n intervals of subsequent program tables containing Pulse Count Instructions will have no effect on the reset time interval The maximum input frequency is 250KHz The maximum number that can be stored in an accumulation register is 65 535 When datalogger time is changed whether through the keyboard or with a telecommunications program a partial recompile is automatically done to resynchronize progr...

Страница 93: ... 12 FP Offset Input locations altered 1 per repetition 5 AC HALF BRIDGE FUNCTION This Instruction is used to apply an excitation voltage to a half bridge Figure 13 5 1 make a single ended voltage measurement of the bridge output reverse the excitation voltage then repeat the measurement The difference between the two measurements is used to calculate the resulting value which is the ratio of the m...

Страница 94: ...ross the reference resistor PAR DATA NO TYPE DESCRIPTION 01 2 Repetitions 95 max 02 2 Range code for both measurements Table 9 1 03 2 Analog card number for first measurement 04 2 Single ended channel number for first measurement 05 2 Excitation card for first measurement 06 2 Excitation channel number for first measurement 07 2 Number of measurements per excitation channel 08 4 Excitation voltage...

Страница 95: ...olynomial error from 40 oC to 55 oC is given below Curve Fit Error Range oC Error oC 40 to 55 1 0 35 to 48 0 1 This instruction uses a single excitation channel since several hundred probes can be driven by a single excitation output For this reason Instruction 11 does not require a measurement excitation parameter A multiplier of 1 and an offset of 0 yields temperature in degrees C PAR DATA NO TY...

Страница 96: ...first measurement 04 2 Excitation card number for first measurement 05 2 Excitation channel number for first measurement 06 2 Number of R H measurements per compensating temperature measurement 07 4 Input location for first compensating temperature measurement 08 4 Input location for first measurement 09 FP Multiplier 10 FP Offset Input locations altered 1 per repetition 13 THERMOCOUPLE TEMPERATUR...

Страница 97: ...splay A multiplier of 1 and an offset of 0 yields temperature in degrees C PAR DATA NO TYPE DESCRIPTION 01 2 Repetitions 02 2 Range code Table 9 1 03 2 Card number 04 2 Beginning channel 05 2 TC type code Table 9 3 06 4 Reference temperature location When indexed this is incremented with each rep 07 4 Input location number 08 FP Multiplier 09 FP Offset Input locations altered 1 per repetition 16 T...

Страница 98: ... given in the B mode Recording the signature allows detection of any program change or ROM failure PAR DATA NO TYPE DESCRIPTION 01 4 Input location number Input locations altered 1 20 PORT SET FUNCTION This instruction sets a specified Digital Control output port or is used to set the active excitation card for port commands with Program Control Instructions or manual toggling Section 1 3 3 Ports ...

Страница 99: ...MER FUNCTION This instruction will reset a timer or store the elapsed time registered by the timer in an Input Storage location Instruction 26 can be used with Program Control Instructions to measure the elapsed time between specific input conditions There is only one timer and it is common to all tables e g if the timer is reset in Table 1 and later in Table 2 a subsequent instruction in Table 1 ...

Страница 100: ...ude counts duty cycle and state This instruction is not in all PROM options The SW8A is addressed by the datalogger allowing multiple SW8A s to be connected to one datalogger 16 addresses are available If more channels are requested than exist in one module the datalogger automatically increments the address and continues to the next SW8A The address settings for multiple SW8A s must sequentially ...

Страница 101: ...A NUMBER TYPE DESCRIPTION 01 2 Repetitions number of outputs 02 2 SDM address base 4 00 33 03 4 Starting input location number C1 is Data line C2 is Clk Hand Shake line C3 is SDE Enable line Input locations read 1 per repetition 104 SDM CD16AC The SDM CD16AC Control Port Expansion Module has 16 digital control ports with drivers Each port can be controlled by a datalogger or controlled manually wi...

Страница 102: ...4 Bit period 10µs units Normally this parameter represents the bit period If the parameter is indexed the value entered is an Input Location that contains the bit period to use NOTE The SDM SI04 Instruction 113 automatically adjusts the SDM communication rate to the fastest that will work 118 SDM OBD2 FUNCTION Instruction 118 is used to read sensor values in from an On Board Data Acquisition II de...

Страница 103: ... 32 INCREMENT INPUT LOCATION Z Z 1 FUNCTION Add 1 to the current value in input location Z PAR DATA NO TYPE DESCRIPTION 01 4 Destination for input location Z Input locations altered 1 33 X Y FUNCTION Add the value in Input location X to the value in location Y and place the result in location Z PAR DATA NO TYPE DESCRIPTION 01 4 Input location of X X 02 4 Input location of Y Y 03 4 Dest input locat...

Страница 104: ...ations altered 1 39 SQUARE ROOT FUNCTION Take the square root of the value in location X and place the result in location Z If the value in X is negative 0 will be stored as the result PAR DATA NO TYPE DESCRIPTION 01 4 Input location of X X 02 4 Dest input location for X 1 2 Z Input locations altered 1 40 LN X FUNCTION Take the natural logarithm of the value in location X and place the result in l...

Страница 105: ...ivided by F e g 3 MOD 2 1 X MOD 0 returns X PAR DATA NO TYPE DESCRIPTION 01 4 Input location of X X 02 FP Fixed divisor F 03 4 Dest input location for X MOD F Z Input locations altered 1 47 XY FUNCTION Raise the value in location X to the value in location Y power and place the result in location Z PAR DATA NO TYPE DESCRIPTION 01 4 Input location of X X 02 4 Input location of Y Y 03 4 Dest input l...

Страница 106: ...cations altered 1 or 2 51 SPATIAL AVERAGE FUNCTION Calculate the average of the values in the given set or SWATH of contiguous input locations and place the result in location Z PAR DATA NO TYPE DESCRIPTION 01 2 Swath SWATH 02 4 Starting input location 1ST LOC 03 4 Dest input location for average AVG or Z Input locations altered 1 53 SCALING ARRAY WITH MULTIPLIER AND OFFSET FUNCTION Take 4 input l...

Страница 107: ...m the air temperature oC and place it in an input location The algorithm for obtaining SVPW from air temperature oC is taken from Lowe Paul R 1976 An Approximating Polynomial for Computation of Saturation Vapor Pressure J Appl Meteor 16 100 103 Saturation vapor pressure over ice SVPI in kilopascals for a 0 oC to 50 oC range can be obtained using Instruction 55 and the relationship SVPI 00486 85471...

Страница 108: ...sed to aid in the conversion of a ratiometric Bridge measurement by obtaining the value for Rs which is equivalent to Rf X 1 X where X is the value derived by the standard CR7 Bridge Measurement Programs with appropriate multiplier and offset Section 13 5 and Rf represents the MULTIPLIER value The result of Instruction 59 is stored in the same location that X was PAR DATA NO TYPE DESCRIPTION 01 2 ...

Страница 109: ...he subinterval averaging periods This feature allows the recording of statistical data over longer time periods by removing the effect of longer period frequencies in the input signals i e it provides a high pass filter For example assume the variance of an input is desired It is determined that the averaging period should not exceed five minutes due to variation in the mean over longer time inter...

Страница 110: ...on of Kth and Ith value MAXIMUM NUMBER OF POSSIBLE OUTPUTS No limitation exists on the number of inputs that can be processed by the CV CR Instruction but the processing time and Intermediate Storage requirements increase rapidly The instruction requires that the input values reside sequentially in Input Storage Since the number of outputs is specified for each type of statistical calculation the ...

Страница 111: ... an execution interval Overrun see Section 2 1 of CR7 Operator s Manual is noted by decimal points on either side of the G in LOG 0 MODE This results in the omission of one input sample The calculations are not affected however since the number of input samples is incremented only when valid input processing occurs Averaging period processing occurs only when the number of input samples specified ...

Страница 112: ...ove instructions i e 31 and 54 to obtain the proper input order The slower alternative is to order separate measurement instructions directly as required by the CV CR Instruction While avoiding move instructions this approach uses more measurement instructions The reason the first method is in general faster is that less overhead time is required in going from one measurement to another within a s...

Страница 113: ... case instruction 89 can be used to check wind speed and if less than the threshold Instruction 30 can set the input location equal to 0 Standard deviation can be processed one of two ways 1 using every sample taken during the output period enter 0 for parameter 2 or 2 by averaging standard deviations processed from shorter sub intervals of the output period enter the number of scans in the sub in...

Страница 114: ...ated using Campbell Scientific s wind speed weighted algorithm Use of the resultant mean horizontal wind direction is not recommended for straight line Gaussian dispersion models but may be used to model transport direction in a variable trajectory model Measured raw data Si horizontal wind speed θi horizontal wind direction Uei east west component of wind Uni north south component of wind N numbe...

Страница 115: ... 2 Repetitions 02 2 Time of maximum optional 03 4 Starting input location number Outputs generated 1 per repetition plus 1 or 2 with time of max option CODE OPTIONS 00 Output the maximum or minimum value ONLY 01 Output the max or min value with SECONDS information 10 Output the max or min value with HOUR MINUTE information 11 Output the max or min value with HR MIN SEC information 74 MINIMUM FUNCT...

Страница 116: ...ed on the basis of different bin select values The weighted value location will be incremented if it is entered as an indexed location key C at some point while keying in Parameter 5 two dashes will appear on the right of the display At the user s option the histogram may be either closed or open The open form includes all values below the lower range limit in the first bin and all values above th...

Страница 117: ...erated 0 79 SAMPLE ON MAXIMUM OR MINIMUM FUNCTION Instruction 79 samples specified input location values at the time a new maximum or minimum value is detected by a previous Maximize 73 or Minimize 74 Instruction When the Output Flag is set the values are transferred to Final Storage Instruction 79 must directly follow the maximum or minimum Instruction to which it refers If the previous Instructi...

Страница 118: ... option 03 Output Array ID if options 0 2 1 511 are valid IDs 82 STANDARD DEVIATION IN TIME FUNCTION Calculate the standard deviation STD DEV of a given input location The standard deviation is calculated using the formula S ΣXi 2 ΣXi 2 N N 1 2 where Xi is the ith measurement and N is the number of samples PAR DATA NO TYPE DESCRIPTION 01 2 Repetitions 02 4 Starting input location number Outputs ge...

Страница 119: ...is instruction marks the start of a subroutine A subroutine is a series of instructions beginning with Instruction 85 and terminated with Instruction 95 END All subroutines must be placed in Table 3 Subroutine Table When a subroutine is called by a command in a Program Control Instruction the subroutine is executed then program flow continues with the instruction following that which called the su...

Страница 120: ... 1 will not be able to interrupt Input locations for Processing Instructions within a loop can be entered as Indexed locations An Indexed location causes the input location to be incremented by 1 with each pass through the loop The Index counter is added to the location number in the program table Input locations which are not indexed will remain constant To specify an Indexed location depress the...

Страница 121: ...t Location 16 to average the vapor pressure over the hour The actual keyboard entries for the examples are shown below with the first example Instruction location equal to 10 The Input Instructions to make the pressure and temperature measurements are assumed TABLE 12 3 Loop Example Block Data Transform 10 P87 Beginning of Loop 01 0 Delay 02 5 Loop Count 11 P57 Wet Dry Bulb Temp to VP 01 10 Pressu...

Страница 122: ...TA NO TYPE DESCRIPTION 01 4 Input location for X 02 2 Comparison code Table 12 5 03 4 Input location for Y 04 2 Command Table 12 2 Input locations altered 0 Execution time 0 6ms TABLE 12 5 Comparison Codes Parameter 1 Function 1 IF X Y 2 IF X Y 3 IF X Y 4 IF X Y 89 IF X COMPARED TO F FUNCTION This instruction compares an input location to a fixed value and if the result is true performs the specif...

Страница 123: ...cution is allowed in any minute e g if the command is to set the Output Flag and the execution interval of the table is ten seconds there will only be one output generated by this instruction not six The Output Flag Flag 0 is a special case in that it will automatically be set low if it is not time to set it high PAR DATA NO TYPE DESCRIPTION 01 4 Time into interval minutes 02 4 Time interval minut...

Страница 124: ...lect whether the instruction is to control the tape Storage Module or the printer output and if the printer is selected the format and baud rate Instruction 96 must be entered separately for each output device used Instruction 96 uses the same Printer pointer as the 9 mode which can be used to get a residual or partial dump of Final Storage Section 4 Do not use 4 to activate a device that is activ...

Страница 125: ...ies of measurements prescribed by an Input Instruction the CR7 makes a calibration measurement The calibration is accomplished by measuring two known voltages which are sent through the same amplifier circuit that will be used for the measurements The calibration for a single ended measurement consists of measuring a voltage which is 4 5ths of full scale and then making a measurement with the inpu...

Страница 126: ... indicate a signal of 1V However if the high input is at 5 8V and the low input is at 4 8V the measurement can not be made because the high input is outside of the CR7 common mode range the CR7 will indicate the overrange with the maximum negative number Section 2 2 Problems with exceeding common mode range may be encountered when the CR7 is used to read the output of external signal conditioning ...

Страница 127: ...e provided Finally techniques are discussed for minimizing input settling error when long leads are mandatory 13 3 1 THE INPUT SETTLING TIME CONSTANT The rate at which an input voltage rises to its full value or that a transient decays to the correct input level are both determined by the input settling time constant In both cases the waveform is an exponential Figure 13 3 1 shows both a rising an...

Страница 128: ... sensor e g a thermistor configured as a half bridge Figure 13 3 3 shows Figure 13 3 2 redrawn in terms of the resistive paths determining the source resistance Ro is given by the parallel resistance of Rs and Rf as shown in Equation 13 3 8 FIGURE 13 3 2 Typical Resistive Half Bridge FIGURE 13 3 3 Source Resistance Model for Half Bridge Connected to the CR7 Ro RsRf Rs Rf 13 3 8 If Rf is much small...

Страница 129: ...negligible dielectric absorption Teflon insulation is also very good but quite expensive 13 3 2 EFFECT OF LEAD LENGTH ON SIGNAL RISE TIME In the 024A Windvane a potentiometer sensor the peak transient voltage is much less than the true signal voltage Table 13 3 5 This means the signal rise time is the major source of error and the time constant is the same as if Cw were between the signal lead and...

Страница 130: ...ttle to the correct signal voltage to avoid errors NOTE Excitation transients are eliminated if an option exists to contain excitation leads in a shield independent from the signal leads FIGURE 13 3 6 Resistive Half Bridge Connected to Single Ended CR7 Input The size of the peak transient is linearly related to the excitation voltage and increases as the bridge resistor Rf increases Table 13 3 4 s...

Страница 131: ... limitation for the 107 sensor The sensors in the WVU 7 are the same as in the Model 107 the lead wire is different but the signal leads for the WVU 7 wet and dry bulbs are not subject to excitation transients because they are shielded independently from the excitation The comparatively small transient yet large source resistance of the 024A sensor indicates that signal rise time may be the most i...

Страница 132: ...f the CR7 input but offers no improvement over configuration A because R f still combines with the lead capacitance to slow the signal response at point P The source resistance at point P column 5 is essentially the same as the input source resistance of configuration A Moving Rf out to the thermistor as shown in Figure 13 3 7C optimizes the signal settling time because it becomes a function of Rf...

Страница 133: ... run excitation leads and signal leads in separate shields to minimize transients 4 AVOID PVC INSULATED CONDUCTORS to minimize the effect of dielectric absorption on input settling time 5 Use the CR7 to measure the input settling error associated with a given configuration For example assume long leads are required but the lead capacitance Cw is unknown Configure Rf on a length of cable similar to...

Страница 134: ...f extension lead connected directly to the pigtails Normally the signal voltage is proportional to Rf Rs Rb Rf but when the pigtails are extended the signal is proportional to Rf Rl Rs Rb Rf Rl Rl is much smaller than the other terms in the denominator and can be discarded The effect on the signal can be analyzed by taking the ratio of the signal with extended leads Vsl to the normal signal Vs Vsl...

Страница 135: ...culate the temperature difference between the reference and measuring junctions it will subtract the reference temperature before storing the temperature value 13 4 1 ERROR ANALYSIS The error in the measurement of a thermocouple temperature is the sum of the errors in the reference junction temperature the thermocouple output deviation from standards published in NBS Monograph 125 the thermocouple...

Страница 136: ...d by the CR7 TABLE 13 4 1 Limits of Error for Thermocouple Wire Reference Junction at 0oC Limits of Error Thermocouple Temperature Whichever is greater Type Range oC Standard Special T 200 to 0 1 0 o C or 1 5 0 to 350 1 0 o C or 0 75 0 5 o C or 0 4 J 0 to 750 2 2 o C or 0 75 1 1 o C or 0 4 E 200 to 0 1 7 o C or 1 0 0 to 900 1 7 o C or 0 5 1 0 o C or 0 4 K 200 to 0 2 2 o C or 2 0 0 to 1250 2 2 o C ...

Страница 137: ...ange of temperatures In order to speed processing and accommodate the CR7 s math and storage capabilities 4 separate 6th order polynomials are used to convert from volts to temperature over the range covered by each thermocouple type Table 13 4 2 gives error limits for the thermocouple polynomials TABLE 13 4 2 Limits of Error on CR7 Thermocouple Polynomials Relative to NBS Standards TC Limits of T...

Страница 138: ...01 of 10mV which at 45 oC changes the temperature by 0 012 oC The RTD is 25 oC but is indicating 25 1 oC and the terminal that the thermocouple is connected to is 0 05 oC cooler than the RTD TABLE 13 4 4 Example of Errors in Thermocouple Temperature Source Error oC of Total Error 1oC 1 Slope Error Error Reference Temp 0 15 12 8 39 9 TC Output ANSI 1 0 85 0 0 01 x 20 o C 0 2 53 2 Voltage Measuremen...

Страница 139: ... must be provided when a junction box is installed in the field Care must also be taken that a thermal gradient is not induced by conduction through the incoming wires The CR7 can be used to measure the temperature gradients within the junction box 13 5 BRIDGE RESISTANCE MEASUREMENTS There are five bridge measurement instructions included in the standard CR7 software Figure 13 5 1 shows the circui...

Страница 140: ...SECTION 13 CR7 MEASUREMENTS 13 16 FIGURE 13 5 1 Circuits Used with Instructions 4 9 ...

Страница 141: ... 7 3 Wire Compensates for lead Half Bridge wire resistance assuming resistance is same in both wires Two single ended measurements at each excitation polarity Ratiometric output 9 6 Wire Compensates for lead Full Bridge wire resistance Two or 4 Wire differential Half Bridge measurements at each excitation polarity Ratiometric output Calculating the actual resistance of a sensor which is one of the...

Страница 142: ...s 1 1 5 59 42 Mult 1 ofs 0 Mult 1 Rs ofs 0 6 or 9 X R R R R R R 1000 3 3 4 2 1 2 used for full bridge R X X R 1 1 1 2 1 1 6 or 9 59 42 Mult 0 001 ofs R3 R3 R4 Mult 1 R2 where X1 3 3 4 1000 X R R R R R X X 2 1 2 2 1 6 or 9 59 Mult 0 001 ofs R3 R3 R4 Mult R1 where X2 1 X R R X X 3 4 3 3 1 6 or 9 59 Mult 0 001 ofs R2 R1 R2 Mult R4 where X3 2 1 2 1000 X R R R R X X R 4 4 4 3 1 1 6 or 9 59 42 Mult 0 00...

Страница 143: ...he model diagrammed in Figure 13 6 2 FIGURE 13 6 2 Model of Resistive Sensor with Ground Loop In Figure 13 6 2 Vx is the excitation voltage Rf is a fixed resistor Rs is the sensor resistance and RG is the resistance between the excited electrode and CR7 earth ground With RG in the network the measured signal is V V R R R R R R x s s f s f G 1 13 6 1 RsRf RG is the source of error due to the ground...

Страница 144: ...count obtained during the previous correct sampling interval PULSE COUNT MEASUREMENTS USING MULTIPLE I O MODULES Pulse channels contained in multiple I O Modules are read and reset based on the program table priority Within a specific program table the channels are reset according to the priority of the I O Module i e Module 1 first and Module 4 last For example if Table 1 and 2 have simultaneous ...

Страница 145: ...considerations 14 1 1 ACCESS PORTS FITTED WITH ELBOWS Standard 0 75 dia male conduit elbows may be screwed directly into the conduit bushings provided with the standard environmental enclosure Elbows allow entry of individual sensor leads and power cables while preventing precipitation from entering the enclosure directly Silicon sealer can be used to seal off the space between the elbow wall and ...

Страница 146: ...t the factory A temperature compensated 12V CHARGING REGULATOR CIRCUIT BOARD beneath the Control Module regulates the charging voltage supplied to the lead acid batteries and the voltage to the CR7 operating system DC Power sources are connected to the terminal block on the charging regulator board The terminals labeled EXT BATT are for connecting a 12V power source The terminals labeled SOLAR are...

Страница 147: ...7 is active it draws approximately 100mA so the actual current drain is a function of the program being executed 14 2 2 SOLAR PANELS Auxiliary photovoltaic power sources such as Solarex Models MSX5 MSX10 and MSX18 Solar Panels may be used to maintain charge on lead acid batteries TABLE 14 2 1 Solar Panel Specifications MSX5 MSX10 MSX18 Typical Peak Power 4 2 8 9 18 6 Watts Current Peak 27 59 1 06 ...

Страница 148: ...using 22 AWG lead wires or larger when connecting an external battery to the CR7 14 2 4 CONNECTING TO VEHICLE POWER SUPPLY When the starting motor of a motor vehicle with a 12 Volt electrical system is engaged the voltage drops considerably below the nominal 12 volts If the CR7 were connected directly to the vehicle power supply the CR7 batteries would be pulled down as well causing the CR7 to bom...

Страница 149: ...connectors for use with the sealed fiberglass enclosure such that the CR7 operates in a gas tight environment Various connector options and associated details are described in Section 12 Desiccant is still required with this method 14 3 3 NITROGEN PURGING Several CSI customers have had success in preventing humidity related equipment malfunctions in harsh environments by allowing nitrogen gas to s...

Страница 150: ...g common mode range may be encountered when the CR7 is used to read the output of external signal conditioning circuitry if a good ground connection does not exist between the external circuitry and the CR7 When operating where AC power is available it is not always safe to assume that a good ground connection exists through the AC wiring If a CR7 is used to measure the output from a laboratory in...

Страница 151: ... can avoid confusion by following 4 steps 1 Categorize the cards 2 Assign a valid number to each card 3 Set the jumpers on the cards according to the numbers assigned 4 Insert the cards into the Control Module making certain that the correct number tag is secured with each card Figure 10 1 1 Tables 15 1 2 and 15 1 3 list card numbers and the corresponding jumper placement The bus structure allows ...

Страница 152: ...SECTION 15 I O CARD ADDRESSING AND MULTIPLE I O MODULES 15 2 FIGURE 15 1 1 Position of Decoding Jumpers on Excitation Pulse Counter and Analog Input Cards ...

Страница 153: ...SECTION 15 I O CARD ADDRESSING AND MULTIPLE I O MODULES 15 3 TABLE 15 1 2 Jumper Settings for Excitation and Pulse Counter Cards ...

Страница 154: ...rack mounting M197 or mounting in a NEMA type enclosure uses M720 Back Mount Brackets The 720XL I O Module mounts directly in a 19 rack or may be mounted in a NEMA type enclosure with the Model M720 Back Mount Brackets TABLE 15 2 1 SC94 Pin Description Pin ID Control Module I O Module A Transmit data Receive data B Transmit data return Receive data return C Receive data return Transmit data return...

Страница 155: ...he Model ENC 7F or the Model ENC 7L enclosure option the space normally taken up by the Control Module can be used for housing the PS12 LA Power Supply The PS12 LA 12V charging regulator and battery may also be mounted with a remote I O Module inside a NEMA type enclosure Multiple I O Modules can be powered by a single Power Supply if the distance is not too great Once all grounding leads are in p...

Страница 156: ...odule s does not exceed 1 000 ft Distances in excess of 1 000 ft require a slower baud rate setting to compensate for connector capacitance Slower baud rates may limit table Execution Intervals or throughput rate Table 15 2 3 lists recommended baud rates for communicating with I O Modules at varying distance from the Control Module TABLE 15 2 3 Recommended Baud Rates for Remote I O Modules Distanc...

Страница 157: ...SECTION 15 I O CARD ADDRESSING AND MULTIPLE I O MODULES 15 7 Figure 15 2 1 Location of Jumper Controlling Baud Rate to I O Modules ...

Страница 158: ...SECTION 15 I O CARD ADDRESSING AND MULTIPLE I O MODULES 15 8 Figure 15 2 2 Location of I O Module Jumper Controlling Baud Rate between the I O Module and the Control Module ...

Страница 159: ...ess frequently than programmed FINAL STORAGE That portion of memory allocated for storing Output Arrays Final Storage may be viewed as a ring memory with the newest data being written over the oldest Data in Final Storage may be displayed using the 7 Mode or sent to various peripherals HIGH RESOLUTION A high resolution data value has 5 significant digits and may range in magnitude from 00001 to 99...

Страница 160: ...ruction PARAMETER When used in conjunction with CR7 instructions parameters are numbers or codes which are entered when programming the CR7 to specify exactly what the instruction is to do Once the instruction number has been entered in a Program Table the CR7 will prompt for the parameters by displaying the parameter number in the ID Field of the display PROCESSING INSTRUCTIONS These Instructions...

Страница 161: ...ughput rate is the rate at which a measurement can be made scaled to engineering units and the reading stored in Final Storage The CR7 I O Module has the ability to scan sensors at a rate exceeding the throughput rate see SAMPLE RATE The primary factor affecting throughput rate is the amount of processing specified by the user In normal operation all processing called for by an instruction must be...

Страница 162: ...APPENDIX A GLOSSARY A 4 This is a blank page ...

Страница 163: ...08 10000 PROM Version 0 1 A 09 0004 PROM Revision 4 A 11 00 1A 01 21444 RAM Sig of I O Mod 1 12196 357 EPROM Sig of I O Mod 1 OR 11 00 38407 357A 1 PROM 357A and a hardware modification make the slow integration time 20 ms one 50 Hz cycle This option is available for countries where 50 Hz Ac power is used CR7 SYSTEMS WITH 2 OR MORE I O MODULES 2A 02 21444 RAM Sig of I O Mod 2 12196 357 EPROM Sig o...

Страница 164: ...B 2 This is a blank page ...

Страница 165: ... will be then reset or if it is reset it will be set 3 b is a 1 byte value whose MSB will determine whether Final Storage Data is returned after the K command If the bit is set Final Storage Data if any will be returned after the next K command The datalogger initially has this bit reset upon entering telecommunications but once set by a J command it will remain set until reset by another J comman...

Страница 166: ...econds Thus the datalogger time for 01 59 01 C6 HEX is 5 45 45 4 The Flags byte expresses datalogger user flag status The most significant bit represents Flag 8 and so on to the least significant bit which represents Flag 1 If a bit is set the user flag is set in the datalogger The optional ports byte expresses the datalogger port status The most significant bit represents Port 8 and so on to the ...

Страница 167: ...ding zero The most significant bit is 0 so the Sign is POSITIVE The exponent is found by subtracting 40 HEX from the remaining least significant bits Converting the binary to hexadecimal 1000100 BINARY 44 HEX or 68 decimal 44 40 HEX 4 HEX Or in decimal 68 64 4 Exponent is 4 decimal The binary equivalent of Data bytes 2 to 4 is 11011001 10011001 10011010 Summing all the fractional values 2 1 2 2 2 ...

Страница 168: ...X 1 1 X XXX DATA TYPE WHEN D E F ALL EQUAL ONE If D E and F are all ones the data type is determined by the other bits as shown below X implies a don t care condition i e the bit can be either 1 or 0 and is not used in the decode decision A B C D E F G H DATA TYPE AND SECOND BYTE FORMAT 1 1 1 1 1 1 0 X A B C 1 Start of output array G 0 H is the most significant bit of the output array ID All 8 bit...

Страница 169: ... calculates the signature using each transmitted byte except the 2 byte signature itself By calculating the signature of the received data and comparing it to the transmitted signature it can be determined whether the data was received correctly SIGNATURE ALGORITHM S1 S0 represent the high and low bytes of the signature respectively M represents a transmitted data byte n represents the existing by...

Страница 170: ...APPENDIX C BINARY TELECOMMUNICATIONS C 6 This is a blank page ...

Страница 171: ...he cards are numbered differently SUGGESTED INSTRUMENTS Five and one half digit digital volt meter DVM with 10 microvolt resolution The accuracy of the DVM needs to be equal to that of the CR7 which is 1 mV at 5 VDC PROCEDURE 1 With a small flat screw driver pry off the three silver caps on the top of the Analog Interface Card in the I O module see Figure D 2 1 2 Monitor the Digital to Analog Conv...

Страница 172: ...TRUMENTS Digital frequency counter STD Bus extender card PROCEDURE 1 Remove the CPU card from the control module Insert an STD Bus extender card into the emptied slot Plug the CPU card into the extender card This is the best way to gain access to the adjustment points However if an extender card cannot be obtained remove all the other cards and move the CPU card into the back most slot for better ...

Страница 173: ...APPENDIX D CALIBRATION PROCEDURES D 3 FIGURE D 2 1 Calibration Points for the Analog Interface Card ...

Страница 174: ...APPENDIX D CALIBRATION PROCEDURES D 4 FIGURE D 2 2 CR7X CPU Card ...

Страница 175: ...ription of A Mode Data 1 5 1 6 1 Description of B Mode Data 1 6 1 7 1 C Mode Entries and Codes 1 7 1 8 1 D Mode Commands 1 7 1 8 2 D Mode Baud Rate and Storage Module Codes 1 7 1 8 3 Program Load Error Codes 1 8 1 8 4 Example Program Listing From D Command 1 1 8 2 INTERNAL DATA STORAGE 2 2 1 Resolution Range Limits of 21X Data 2 2 2 2 2 Decimal Location in Low Resolution Format 2 3 2 3 1 7 Mode Co...

Страница 176: ...SUREMENTS 13 3 1 Exponential Decay Percent of Maximum Error vs Time in Units of τ 13 4 13 3 2 Properties of Three Belden Lead Wires Used by Campbell Scientific 13 5 13 3 3 Settling Error in Degrees for 024A Wind Direction Sensor vs Lead Length 13 6 13 3 4 Measured Peak Excitation Transients for 1000 Foot Lengths of Three Belden Lead Wires Used by Campbell Scientific 13 6 13 3 5 Summary of Input Se...

Страница 177: ... 6 5 1 Transmitting the ASCII Character 1 6 4 7 MEASUREMENT PROGRAMMING EXAMPLES 7 1 1 Wiring Diagram for LI200S 7 1 7 2 1 Typical Connection for Active Sensor with External Battery 7 2 7 4 1 Thermocouples with External Reference Junction 7 2 7 5 1 Connection for Thermocouple Differential Temperature Measurement 7 3 7 9 1 Wiring Diagram for Anemometer 7 6 7 10 1 Wiring Diagram for Raingage with Lo...

Страница 178: ...4 1 Diagram of Sensor Junction Box 13 15 13 5 1 Circuits Used with Instructions 4 9 13 16 13 5 2 Excitation and Measurement Sequence for 4 Wire Full Bridge 13 17 13 6 1 AC Excitation and Measurement Sequence for AC Half Bridge 13 19 13 6 2 Model of Resistive Sensor with Ground Loop 13 19 14 INSTALLATION 14 2 1 Connecting Vehicle Power Supply to CR7 14 4 14 5 1 Typical Connection for Activating Pow...

Страница 179: ...I Characters 6 4 Definition A 1 Dumping in Telecommunications Mode 5 3 Program listing D Mode 1 7 Standard 6 4 Transmission 6 4 Average Instruction 71 11 3 Computing running 8 1 B Battery power options External 14 4 Caution vi Sealed lead acid 14 2 Solar panels with 21XL 14 3 Vehicle power supply 14 4 Battery Voltage Instruction 10 9 5 Baud rate Definition A 1 6 4 Output Codes 4 1 Setting between ...

Страница 180: ...Instruction 86 12 1 DPTR 2 1 DSP see Data Storage Pointer DTE pin configuration 6 3 Duplex Definition 6 4 E Editing datalogger programs OV 14 Editor errors 3 9 EDLOG OV 7 5 3 ELSE Instruction 94 12 5 Enclosures Environmental 14 1 Gas tight vi END Instruction 95 3 5 12 6 Programming example 8 2 Error codes 3 9 Overranging 3 2 Overrun occurrences 1 1 Ex Del SE Instruction 4 9 3 Excit Del Instruction...

Страница 181: ...ormat 2 3 Definition OV 3 A 1 Displaying 6 Mode Example of OV 12 Erasing with 0 B or D Mode 1 2 Input Output Instructions I O 9 1 Definition OV 5 A 1 Memory and execution times 3 6 Voltage range parameter 3 2 Installation and maintenance 14 1 Instruction location number A 1 Instruction memory and execution time 3 6 Instruction Set Format OV 9 Types OV 6 Integer data type parameter 3 1 Integer Valu...

Страница 182: ...running execution interval 1 1 Overview of CR7 OV 1 P Parameter Definition A 2 Data types 3 1 Parity Checking 6 4 PC201 Tape Read Card 4 5 PC208 Datalogger Support Software 5 3 Password Security 1 6 Peripherals Enabling 6 2 General 4 1 Power requirements 14 1 Physical description of CR7 OV 1 Pin configuration 9 pin serial I O port 6 1 Polynomial Instruction 55 10 5 Programming example 7 13 7 14 Po...

Страница 183: ...le rate 1 1 Definition A 2 Saturation Vapor Pressure Instruction 56 10 5 SC32A RS232 Interface 6 3 SC92A 93A Use tape recorder 4 4 Scaling Array with Multiplier Offset Instruction 53 10 4 SDM CD16 16 Channel Port Expansion Module Instruction 29 9 9 Security 1 6 5 3 Select I O Module Instruction 23 9 9 Send Character Instruction 98 12 8 Sensors Effect of lead length on signal settling time 13 3 Eff...

Страница 184: ...rom thermocouples see Thermocouple temperature Temperature of Input Panel Instruction 17 9 7 Programming example OV 11 Temperature range CR7 14 1 TERM 5 3 Thermocouple temperature Calibration 7 4 Differential voltage Instruction 14 9 7 Programming examples 7 3 Single Ended Voltage Instruction 13 9 6 Programming example 7 4 7 5 Technique error analysis 13 11 Using external reference junction 7 2 Th...

Страница 185: ...Z ABS X Instruction 43 10 3 Z ARCTAN X Y Instruction 66 10 10 Z EXP X Instruction 41 10 2 Z F Instruction 30 10 1 Z FRAC X Instruction 44 10 3 Z INT X Instruction 45 10 3 Z LN X Instruction 40 10 2 Z SIN X Instruction 48 10 3 Z SQRT X Instruction 39 10 2 Z X Instruction 31 10 1 Z X F Instruction 37 10 2 Z X F Instruction 34 10 1 Z X Y Instruction 36 10 2 Z X Y Instruction 33 10 1 Z X Y Instruction...

Страница 186: ...CR7 INDEX I 8 This is a blank page ...

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