Siemens S5-135U/155U System Manual page 145

Removal
Proceed as follows to remove the CPU:
Step
Note
Only operate the CPU 948 -3UA13 or the CPU 948 -3UA23 with the
submodule receptacle closed. You close it either by fitting an interface
submodule or with the cover supplied.
System Manual
C79000-G8576-C199-06
CPUs, Memory Cards, Memory Submodules, Interface Submodules
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.
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