Siemens SIMATIC S7-400 Hardware And Installation Manual page 84

Wiring the S7-400
Connecting the Load Voltage Ground
Many output modules require an additional load voltage to switch the actuators.
Two different modes are possible for this load voltage:
Non-isolated operation
Floating operation
The following table shows how the load voltage ground is connected in the
individual modes.
Non-isolated operation
Grounded configuration
Ungrounded configuration
Floating operation
Grounded and ungrounded
configuration
The following figure shows how the load voltage ground is connected for
non-isolated operation.
Ground terminal for
load voltage
4-22
www.gkbpx.com
Mode
To the reference point of the rack; metallic connection
between frame element and chassis ground must be
fitted.
To the reference point of the rack; metallic connection
between frame element and chassis ground must be
fitted.
Left open or to any point, but not to protective ground
or reference potential M of operating voltages
Metallic connection; remove for
ungrounded configuration
S7-400 and M7-400 Programmable Controllers, Installation Manual
Connection of Load Voltage
C79000-G7076-C424-01