Siemens SIMATIC Manual page 246

Principles of analog value processing
4.4 Wiring and connecting current transducers
Wiring and connecting 2-wire transducers with power supply from L+
Configure the 2-wire as a 4-wire transducer in
Figure 4-7
Wiring and connecting 4-wire transducers
4-wire transducers are connected to a separately power supply.
Figure 4-8
246
Wiring and connecting a 2-wire transducer with supply from L + to an electrically isolated
AI
Wiring and connecting 4-wire transducers to electrically isolated AI
STEP 7
if it is connected to supply voltage L+.
Manual, 06/2017, A5E00105505-AJ
S7-300 Module data