Siemens SIMATIC ET 200PA SMART Operating Instructions Manual page 156

ET 200PA SMART I/O modules
10.4 Analog input modules
Wiring: Resistance measurement with 2-, 3- and 4-wire connection
The following connection possibilities also apply to silicon temperature sensors and PTCs.
①
②
③
④
⑤
⑥
⑦
⑧
⑨
⑩
⑪
Figure 10-8
Note
It is not necessary to interconnect the M- terminals when measuring using resistors, resistance
thermometers, PTCs, or silicon temperature sensors. However, interconnection of the M-
terminals may enhance interference immunity.
156
2-wire connection. Insert a bridge between M and S (no line resistance compensation).
3-wire connection
4-wire connection. The fourth line may not be wired (remains unused)
4-wire connection. The fourth line is routed to the terminal strip in the cabinet but is not wired.
Internal supply
+ 5 V from backplane bus
Logic and backplane bus interface
Electrical isolation
Multiplexer
Analog to Digital Converter (ADC)
Current source
Block diagram and terminal diagram
Operating Instructions, 06/2019, A5E34192013-AB
ET 200PA SMART