Siemens SIMATIC S7-1500 Manual page 19

Connection: 2-, 3- and 4-wire connection of resistance-based sensors or thermal resistors (RTD)
The example in the following figure shows the pin assignment for 2-, 3- and 4-wire
connections of resistance-based sensors or thermal resistors.
①
4-wire connection
②
3-wire connection
③
2-wire connection
④
Analog-to-digital converter (ADC)
⑤
Backplane bus interface
⑥
Supply voltage via power supply element
⑦
Equipotential bonding cable (optional)
Figure 3-5 Block diagram and pin assignment for 2-, 3- and 4-wire connections
Analog input module AI 8xU/I/RTD/TC ST (6ES7531-7KF00-0AB0)
Manual, 09/2016, A5E03484864-AD
CHx Channel or 9 x channel status (green/red)
RUN Status display LED (green)
ERROR Error display LED (red)
PWR LED for power supply (green)
Wiring
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