Siemens S5-135U/155U System Manual page 229

Inserting
Since the contents of the inserted RAM submodule are erased with each
Programmed
overall reset, proceed as follows when using programmed RAM submodules
Memory whose contents are not to be erased:
Submodules
Initial situation:
Step
Removing Memory
Before removing the RAM submodule, check whether the battery is still in
Submodules
order: if the battery fault LED on the RAM submodule is lit whilst the PLC
supply voltage is switched on, the contents of the RAM submodule will be
lost when it is removed.
Initial situation:
Step
System Manual
C79000-G8576-C199-06
CPUs, Memory Cards, Memory Submodules, Interface Submodules
The CPU is in the programmable controller.
The power supply of the PLC is switched off.
The mode switch of the CPU is at STOP.
Action
1 Insert another, unprogrammed memory submodule in the CPU.
2 Switch the power supply on.
3 Carry out an overall reset.
4 Switch the power supply off.
5 Remove the unprogrammed memory submodule.
6 Insert the programmed memory submodule.
7 Switch the power supply on.
8 Carry out a reset.
The CPU is in the RUN state.
Action
1 Set the CPU mode switch to STOP.
2 Switch the power supply off.
3 Remove the memory submodule.
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