Connecting Non-Isolated Sensors To A Non-Isolated Ai - Siemens SIMATIC S7-300 Reference Manual

When connecting non-isolated sensors to non-isolated modules, you can operate
the CPU only in Grounded mode.
Non-isolated
sensors
Figure 4-10
Note
You must not use non-isolated two-wire transmitters and non-isolated
resistance-type sensors with a non-isolated AI!
Programmable Logic Controllers S7-300 Module Data
A5E00105505-03
L+
M
M+
M–
M+
M–
U
M
CM
ANA
Equipotential
bonding
conductor

Connecting non-isolated sensors to a non-isolated AI

ADC
Ground bus
Analog Modules
Backplane
bus
CPU
M
internal
L+
M
4-49