Siemens S5-135U/155U System Manual page 174

CPUs, Memory Cards, Memory Submodules, Interface Submodules
Removal
Proceed as follows to remove the CPU:
Step
Note
Only operate the CPU 928B with the submodule receptacle closed. You
close it either by fitting an interface submodule or with the cover supplied.
5-34
Action
1 Release the upper locking bar of the central controller.
2 Release the locking pin of the module.
3 Press the release lever downwards and pull the module forwards
and out of the central controller.
System Manual
C79000-G8576-C199-06