Siemens SIMATIC TOP connect Manual page 29

9. Press the front connector module into the slot until it clicks into place.
Note
Front connector modules with 40-pin connecting cable have a screw instead of a release
button.
For 40-pin front connector modules, tighten the fastening screw in the middle of the front
connector module.
This pulls the front connector module onto the module and establishes the contact.
Figure 4-3
10.Run the connecting cables and the cables for the I/O module supply voltage down and out
of the I/O module.
11.Tighten the strain-relief.
12.Close the front door.
For 32-channel digital modules and Compact CPU for the connection X2:
Relates to the following order numbers:
● 6ES7921-3AA20-0AA0
● 6ES7921-3AB20-0AA0
System cabling for S7-300
Manual, 09/2018, 70327045899
Fitted strain relief (example)
Connecting
4.3 Connecting components
29