Siemens SIMATIC S7 System Manual page 101

Example: One Single-channel Sensor Connected via One Channel to One F-AI (SIL2/Category 3)
The following figure presents the wiring diagram for an SM 336, AI 6 ☓ 13 bit with 4 mA to 20
mA current measurement range and 2-wire transducer output. The sensor is supplied by the
F-I/O. This wiring enables SIL2/Category 3 to be achieved.
Figure 5-9
Safety Engineering in SIMATIC S7
System Manual, 04/2006, A5E00109529-05
5.2 Safety Functions for Achieving Safety Classes for F-I/O with Inputs
Example: Wiring Diagram for One Sensor Connected via One Channel to One F-AI
(1oo2)
Achievable Safety Classes with F-I/O
5-9