Siemens SIMATIC Manual page 248

Principles of analog value processing
4.5 Wiring and connecting resistance thermometers and resistors
3-wire connection of a resistance thermometer (not for 6ES7331-7PF01-0AB0)
When connecting 3-wire devices to modules equipped with four terminals, you should
generally bridge M- and I
to the resistance thermometer.
The image shows the basic wiring. Please observe the notes in the description about the
respective module.
Figure 4-10
2-wire connection of a resistance thermometerError! Bookmark not defined.
For 2-wire connections, insert a bridge between the M
terminals of the module. The line impedance is included in the measurement.
Figure 4-11
248
-. Always wire and connect the connected
C
3-wire connection of resistance thermometers to an electrically isolated analog input
2-wire connection of resistance thermometers to an electrically isolated analog input
+ and M+ lines directly
C
and I and between the M- and I
+ C+
S7-300 Module data
Manual, 06/2017, A5E00105505-AJ
-
C