Analog modules
6.3 Analog input module SM 331; AI 8 x 16 bit; (6ES7331-7NF00-0AB0)
S7-300 Module data
310 Manual, 06/2017, A5E00105505-AJ
Wiring: 2-wire and 4-wire transducers
Analog-to-Digital Converter (ADC)
Channel 0 for 4-wire transducer
Channel 7 for 2-wire transducer (with external supply)
Figure 6-2 Wiring and block diagram