Configuring The Rtd Analog Inputs - Siemens SIMATIC S7 System Manual

6.1.12

Configuring the RTD analog inputs

Click the RTD analog Input node of the system block (Page 133) dialog to configure options
for an RTD analog input module that you have selected in the top section.
Note
The CPU models CPU CR20s, CPU CR30s, CPU CR40s, and CPU CR60s do not support
the use of expansion modules or signal boards.
The RTD analog input module provides a current at terminals I+ and I- for resistance
measurements. The current is fed to the resistance for measuring its voltage potential. The
current cables must be wired directly to the resistance thermometer/resistor.
Measurements programmed for 4-or 3-wire connections compensate for line resistance and
return considerably higher accuracy compared to 2-wire connections.
RTD type configuration
For each RTD input channel, you configure the type, choosing one of the following options:
● Resistance 4-wire
● Resistance 3-wire
● Resistance 2-wire
● Thermal Resistance 4-wire
● Thermal Resistance 3-wire
● Thermal Resistance 2-wire
S7-200 SMART
System Manual, V2.3, 07/2017, A5E03822230-AF
6.1 Configuring the operation of the PLC system
PLC device configuration
153