Campbell Scientific AM25T 25-Channel Solid State Multiplexer - Manual (Page 24)

Appendix A. Single-Ended Measurements
A.1.1 Thermocouple Measurements
Wire the high side of each thermocouple into an input terminal. The low side
of each thermocouple is wired into the adjacent ground terminal (Figure A-1).
FIGURE A-1. Single-ended Measurement of a Type T Thermocouple
Example A-1. CR10 Program for Measuring 50 Type T Thermocouples or Voltage Sensors
Using a Single-Ended Instruction
*Table 1 Program
01: 10
Execution Interval (seconds)
01: Set Port(s) (P20)
;Configure Control Ports for 1 millisecond pulse
1: 9999 C8..C5 = nc/nc/nc/nc
2: 9933 C4..C1 = nc/nc/1ms/1ms
02: Do (P86)
;Turn On AM25T
1: 42 Set Port 2 High
03: Full Bridge (P6)
;Measure the output of the reference temp. full bridge
1: 1 Reps
2: 24 250 mV 60 Hz Rejection Range ;See Table 6-1 for older AM25T multiplexers
3: 1 DIFF Channel
4: 1 Excite all reps w/Exchan 1
5: 1200 mV Excitation ;See Table 6-1 for older AM25T multiplexers
6: 1 Loc [ RefTemp_C ]
7: -0.001 Mult
8: 0.09707 Offset
04: BR Transform Rf[X/(1-X)] (P59)
;Calculate RTD resistance R/R0
1: 1 Reps
2: 1 Loc [ RefTemp_C ]
3: 10.025 Multiplier (Rf)
A-2