Siemens SIMATIC Manual page 398

Analog modules
6.10 Analog input module SM 331; AI 8 x TC; (6ES7331-7PF11-0AB0)
Wiring: Thermocouple with external compensation
With this type of compensation, the temperature of the terminals at the reference junction is
established using a resistance thermometer Pt100 with a temperature range of -25 °C to
85 °C (see terminals 35 to 38).
①
Thermocouple with external temperature compensation
②
Backplane bus interface
③
Analog-to-Digital Converter (ADC)
④
External cold spot comparison
Figure 6-27 Wiring and block diagram
398
S7-300 Module data
Manual, 06/2017, A5E00105505-AJ