Overview: Grounding; Connection Of The Load Voltage Reference Potential - Siemens SIMATIC S7-300 Hardware And Installation Manual

Configuring
Connecting the reference potential of the load voltage
Numerous output modules require an additional load voltage for switching control
devices.
The table below shows how to connect the load voltage reference potential M
for the various configuration versions.
Table 5-9
Installation
grounded
ungrounded Connect M

5.8.6 Overview: Grounding

CPU 31xC
The figure below shows you the complete assembly of an S7-300 with CPU 31xC
with a power supply from TN-S mains.
Apart from powering the CPU, the PS 307 also supplies the load current for the 24
VDC modules.
Note: The arrangement displayed does not correspond with the physical
arrangement; it was merely selected to give you a clear overview.
5-28

Connection of the load voltage reference potential

Non-isolated modules Isolated modules
Connect M with M
external
on the CPU
with M
external
on the CPU
S7-300 Programmable Controller Hardware and Installation
Connect or do not connect
M to the common
external
grounding line
Connect or do not connect
M to the common
external
grounding line
extern
Remarks
-
ungrounded operation
of CPU31xC and
312 IFM is not
possible
A5E00105492-02