Campbell 4WPB100, Руководство по эксплуатации продукта

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Table 3-1: 4WPB100/4WPB1K connections to Campbell Scientific data loggers
Function Label/Wire
GRANITE
analog
ue
input module
GRANITE 6,
CR6
CR3000,
CR1000X,
CR800, CR850,
CR1000
CR9000X
Excitation Black wire X1 U5 VX1 Excitation 1
V1 high H 1H U1 1H 1H
V1 low L 1L U2 1L 1L
Ground G ⏚ ⏚ ⏚ ⏚
1
The GRANITE 9 and GRANITE 10 do not directly make analog
ue
measurements. Instead, they use analog
ue
input
modules such as the VOLT 108 or VOLT 116. When making a half-bridge measurement, the terminal input module is
connected to the analog
ue
input module, which is then connected to the GRANITE 9 or GRANITE 10.
4. Programming examples
The following examples show the two instructions necessary to 1) make the measurement and 2)
calculate the temperature. The result of the half bridge measurement as shown is R
s
/R
0
, the input
required for the PRT algorithm to calculate temperature.
If using a calibrated sensor, the exact measurement of R
0
will be known. Use this value to
increase the accuracy of the
PRTCalc()
instruction by inserting the following equation
between the BrHalf4W() and PRTCalc() instructions in the example programs.
Rs_R0 = Rs_R0*100/R0
where R0 is the sensor resistance at 0 °C
The following examples are for a 100 Ω PRT and 4WPB100. The excitation voltages used were
chosen with the assumption that the temperature would not exceed 50 °C. Calculation of
optimum excitation voltage is discussed in
Excitation voltage (p. 9). Using the 4WPB1K allows for
a higher excitation voltage.
4WPB100, 4WPB1K PRT Bridge Terminal Input Modules 4