Installing the S7-400
2-17
AutomationSystem S7-400 Hardwareand Installation
A5E00850741-01
Connection to the Reference Point
For the connection to the reference point, use a cable lug for M4, a suitable spring
lock washer (for example, clamping washer to DIN 6796) and the cylinder-head
screw supplied.
Ungrounded assembly: Undo the fixing screws of the metallic connection on the
rack. Tiltthe connection downwards. For the connection to the reference point, use
the original M4 x 8 supplied. Use the tilted metallic connection as a washer.
Grounded assembly: Leavethe metallic connection on the rack. For the
connection to the reference point, use the original M4 x 8.
Reference point
Original screw with spring lock washer
M4x8
Connection
Spring lock washer
Original screw with spring lock washer
M4x8
Rack
Ungroundedconfiguration Groundedconfiguration
Metallic connection
Connection
Spring lock washer
Note
Do not use any cylinder-head screws that are longer than 6 mm for the connection
to the reference point. Otherwise, you may create an undesired connection bet-
ween the reference point and the rack profile behind it and therefore the connec-
tion for the chassis ground. For this reason as well, leave the metallic connection
on the rack and use it as a washer in an ungrounded configuration.