Campbell Scientific HMP45C Temperature and RH Probe - Manual (Page 9)

Model HMP45C Temperature and Relative Humidity Probe
4. Wiring
Connections to Campbell Scientific dataloggers are given in Tables 4-1
through 4-3. The probe can be measured by two single-ended or differential
analog input channels.
When measuring the HMP45C with single-ended
measurements, the purple or white and black leads must
both be connected to AG on the CR10(X) and
CR500/CR510 or to
on the CR1000, CR5000, and
CR23X. Doing otherwise will connect the datalogger’s
analog and power ground planes to each other, which in
some cases can cause offsets on low-level analog
measurements. To avoid 4 mA flowing into analog ground,
switch the sensor on/off for its own measurement.
CAUTION
TABLE 4-1. Connections for Single-Ended Measurements
Color Description CR10X
CR1000,
CR3000,
CR800,
CR5000,
CR23X
CR10,
CR510,
CR500 21X, CR7
Yellow Temperature
Signal
Single-Ended
Input
Single-Ended
Input
Single-Ended
Input
Single-Ended
Input
Blue Relative Humidity
Signal
Single-Ended
Input
Single-Ended
Input
Single-Ended
Input
Single-Ended
Input
White Signal Reference AG AG
Black Power Ground AG AG
Shield Shield G G
Red Power
Continuous/Switched
SW12V SW12V 12V/SW12V* 12V/SW12V*
CR10X Power Control
if using SW12V
channel on datalogger
Jumper from
SW12V Control to
Control Port
*On these dataloggers switched power is only available with the SW12V peripheral.
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