Siemens SIMATIC Manual page 381

Pin assignment
The figures below show the various connection options. These connection examples apply to
all channels (channels 0 to 7).
Wiring
Incorrect wiring of the 3-wire connection can result in unpredictable operation of the module
and dangerous conditions in the plant.
Wiring: 2, 3 and 4-wire connection for resistance and thermal resistance measurement
Connection possible at both sides to channels 0 to 7
①
4-wire connection
②
3-wire connection
③
2-wire connection
④
Digital-analog converter
⑤
Backplane bus interface
⑥
Analog-to-digital converter (ADC)
Figure 6-21 Wiring and block diagram
S7-300 Module data
Manual, 06/2017, A5E00105505-AJ
6.9 Analog input module SM 331; AI 8 x RTD; (6ES7331-7PF01-0AB0)
CAUTION
Analog modules
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