Siemens SIMATIC S7-300 Module data - Thermometers to the SM 331; AI 8 X TC

Analog Modules
4-65
Programmable Logic Controllers S7-300 Module Data
A5E00105505-03
Connecting thermocouples with resistance thermometer to the
SM 331; AI 8 x TC
With this type of compensation, the reference junction terminal temperature is
determined by a bulb resistor sensor with a temperature range of -25 °C to 85 °C.
Backplane
bus
ADC
M
L+
Compensating
leads (same
material as
thermocouple)
Ref. junction
Copper
wire
KV–
KV+
Thermo-
couples
IC
+
IC
–
Pt 100
KV+
KV–
KV+
KV–
K0
K7
P5V
M internal
Logic
Figure 4-27 Connecting thermocouples with external compensation via resistance thermometers to the
SM 331; AI 8 x TC