Campbell Scientific AM16/32A Multiplexer - Manual (Page 35)

AM16/32A Relay Analog Multiplexer
COM EVEN H
COM EVEN L
EVEN H
EVEN L
SENSOR SHIELDS COM
"4 X 16" Mode
COM ODD H
COM ODD L
CU
CO
CU
CO
ODD H
ODD L
CU
CO
CU
CO
/
0
21X/
CR7 CR10(X)
CR3000/
CR800/CR850/
00/ CR23X/CR10
CR5000
H H H
L L L
H H H
L L L
G
FIGURE 17. Differential Thermocouple Measurement with Reference Junction at the
Datalogger.
COM EVEN H
COM EVEN L
EVEN H
EVEN L
SENSOR SHIELDS COM
"4 X 16" Mode
COM ODD H
COM ODD L
107
ODD H
ODD L
CU
CO
CU
CO
CU
CU
CU
CU
/
0
CR23X/
CR800/
CR850/
CR1000
21X/
CR7 CR10(X)
CR3000/
CR5000
H H H H
L L L L
EX E E VX
H H H H
AG
H H H H
L L L L
G
FIGURE 18. Differential Thermocouple Measurement with Reference Junction at the
AM16/32A.
If a mix of TCs and other sensor types are multiplexed through the
AM16/32A, it is generally best to locate the reference junction on the
AM16/32A, as shown in Figure 18.
AM16/32A Reference - An external reference, usually a thermistor,
can be located at the AM16/32A, as shown in Figure 18. This
approach requires an additional single-ended datalogger input to
measure the reference. Position the reference next to the COM
terminals and, when practical, measure the thermocouples on SETs
that are in close proximity to the COM terminals in order to minimize
thermal gradients.
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