Siemens Automation System S7-400 - Manual (Page 32)

Installing the S7-400
2-16
Automation System S7-400 Hardware and Installation
A5E00850741-01
2.6 Chassis Terminal Connection in the Non-Isolated
Configuration
Reference Point
The racks offer the option of connecting the 24-V load voltage ground in the
non-isolated configuration to the 5-V ground (reference potential M, logic ground).
Connect the chassis ground to the reference point for non-isolated modules. The
reference point is metallically connected to the reference potential M.
The following figure shows the position of the reference point on a rack.
Grounding terminal
Load voltage ground
connection (reference point)
1 2 3 4 5 6 7
Metallic connection,
disconnect upper screw for
ungrounded assemblies