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4.1 GRANITE 9/10 program example

The GRANITE 9 and GRANITE 10 require the use of an analog input module, such as the
VOLT 108, when making a half-bridge measurement.

CRBasic Example 1: GRANITE 9/10 3-wire half bridge example

'3-wire half bridge example
'GRANITE 9 and GRANITE 10 data loggers (with a VOLT 108)

'Declare Variables and Units

Public

Temp_C_3wire

Public

Rs_R0

'Define Data Tables

DataTable

(Hourly,True,-1)

DataInterval

(0,60,Min,10)

Average

(1,Temp_C_3wire,IEEE4,False)

EndTable

'Main Program

BeginProg

'Configure the VOLT 108 Module and assign it CPI address 'C1'

CPIAddModule

(VOLT108,10,

" "

,C1)

'Main Scan

Scan

(5,Sec,1,0)

'Half Bridge, 3-wire measurements on the VOLT 108

CDM_BrHalf3W

(VOLT108,C1,Rs_R0,1,mV1000,1,1,1,3200,True,500,60,1,0)

'PRT temperature calculation

PRTCalc

(Temp_C_3wire,1,Rs_R0,0,1.0,0)

'Call Data Tables and Store Data

CallTable

Hourly

NextScan

EndProg

3WHB10K 3-Wire Half Bridge Terminal Input Module

5

Содержание 3WHB10K

Страница 1: ...Revision 03 2020 Copyright 1996 2020 Campbell Scientific Inc ...

Страница 2: ...TE 9 10 program example 5 4 2 GRANITE 6 CR6 program example 6 4 3 CR1000X program example 6 4 4 CR1000 program example 7 4 5 CR9000X program example 7 5 100 Ohm PRT in 3 wire half bridge 8 5 1 Excitation voltage 8 5 2 Calibrating a PRT 9 5 3 Compensation for wire resistance 9 Table of Contents i ...

Страница 3: ...ire half bridge measurements and includes a 10 kΩ completion resistor NOTE The GRANITE 6 and CR6 include the fixed resistor and current excitation required to complete the half bridge circuit without a terminal input module However the GRANITE 6 and CR6 are still compatible with a terminal input module and may be used with one should the application require it FIGURE 1 1 Terminal input module 3WHB...

Страница 4: ...djacent H and L terminals When making 3 wire half bridge measurements the 3WHB10K performs two single ended measurements The sense wires from the platinum resistance thermometer PRT attach to the 3WHB10K The black excitation wire is connected to an excitation terminal In the following example the 3WHB10K is connected to the 1H and 1L terminals using them for two single ended measurements The excit...

Страница 5: ... name needs to be changed in the Programming examples p 4 example programs FIGURE 3 1 3 wire half bridge used to measure PRT The terminal spacing of the GRANITE 6 and GRANITE analog input module is different than other data loggers The terminal input modules are still compatible but the pins must be gently bent inward a small amount to allow the terminal input module to be mounted It is still poss...

Страница 6: ...w the two instructions necessary to 1 make the measurement and 2 calculate the temperature The result of the half bridge measurement as shown is Rs R0 the input required for the PRT algorithm to calculate temperature If using a calibrated sensor the exact measurement of R0 will be known Use this value to increase the accuracy of the PRTCalc instruction by inserting the following equation between t...

Страница 7: ...Define Data Tables DataTable Hourly True 1 DataInterval 0 60 Min 10 Average 1 Temp_C_3wire IEEE4 False EndTable Main Program BeginProg Configure the VOLT 108 Module and assign it CPI address CPI_BUSA 1 CPIAddModule VOLT108 10 CPI_BUSA 1 Main Scan Scan 5 Sec 1 0 Half Bridge 3 wire measurements on the VOLT 108 CDM_BrHalf3W VOLT108 CPI_BUSA 1 Rs_R0 1 mV1000 1 1 1 3200 True 500 60 1 0 PRT temperature ...

Страница 8: ...ic Rs_R0 Temp_C DataTable Hourly True 1 DataInterval 0 60 Min 0 Average 1 Temp_C IEEE4 0 EndTable BeginProg Scan 1 Sec 0 0 BrHalf3W Rs_R0 1 mV1000 U1 U4 1 2500 True 0 250 100 0 PRTCalc Temp_C 1 Rs_R0 0 1 0 CallTable Hourly NextScan EndProg 4 3 CR1000X program example CRBasic Example 3 CR1000X 3 wire half bridge example CR1000X series data logger 3 wire half bridge Public Rs_R0 Temp_C DataTable Hou...

Страница 9: ...rue 0 250 100 0 PRTCalc Temp_C 1 Rs_R0 0 1 0 CallTable Hourly NextScan EndProg 4 5 CR9000X program example CRBasic Example 5 CR9000X 3 wire half bridge example CR9000X data logger 3 wire half bridge Public Rs_Ro Temp_F DataTable Temp_F 1 1 DataInterval 0 60 Min 0 Sample 1 Temp_F FP2 EndTable BeginProg Scan 1 mSec 0 0 BrHalf3W RS_Ro 1 mV1000 5 1 6 1 1 3200 True 30 40 100 0 PRTCalc Temp_F 1 Rs_Ro 0 ...

Страница 10: ...ion to obtain the desired intermediate Rs R0 Rs Rf x Rf R0 If Rf and R0 are equal the multiplier is 1 The fixed resistor must be thermally stable The 0 8 ppm C temperature coefficient would result in a maximum error of 0 035 C at 125 C This measurement is ratiometric Rs Rf and does not rely on the absolute values of either Rs or Rf The properties of the 10 kΩ resistor do not affect the result The ...

Страница 11: ... example section multiplier 1 Place the PRT in an ice bath 0 C Rs R0 Read the result of the bridge measurement The reading is Rs Rf which is equal to R0 Rf since Rs R0 The correct value of the multiplier Rf R0 is the multiplier used divided by this reading For example if with a 100 Ω PRT the initial reading is 0 9890 the correct multiplier is Rf R0 100 0 9890 101 11 5 3 Compensation for wire resis...

Страница 12: ... The temperature computed by PRTCalc from the measured ratio would be about 0 1 C lower than the actual temperature of the PRT This source of error does not exist in a 4 wire half bridge where a differential measurement is used to directly measure the voltage across the PRT 3WHB10K 3 Wire Half Bridge Terminal Input Module 10 ...

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Страница 14: ...e shipping container Campbell Scientific s shipping address is CAMPBELL SCIENTIFIC INC RMA _____ 815 West 1800 North Logan Utah 84321 1784 For all returns the customer must fill out a Statement of Product Cleanliness and Decontamination form and comply with the requirements specified in it The form is available from our website at www campbellsci com repair A completed form must be either emailed ...

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