QUESTION:
What is the meaning of the "Change of module during operation" parameter option on an ET 200 M?

ANSWER:
Change of module during operation is a function with which certain modules from the S7 300 range can be removed from or plugged into the rack of the ET200M during operation.
However, the requirement here is that you have an active backplane bus (proper busbar with slots) and not the previous mounting channel with bus connectors.
Furthermore, you need at least an IM153-1AA02... or even newer.
Older modules like the IM153-0 or IM153-1AA00... do not support this function.
The IM 153 must be controlled by an S7-400 CPU, because the S7-300 CPU does not support the pull/plug interrupt.

As of Step7 V5.1 it will be possible for S7-300 to configure remove an plug, in particular when the CP 342-5 is used as DP master. Here you must remember that the connection to the CPU only functions via the FCs supplied. This means that an associated interrupt OB is not called. The remove/plug interrupt is also registered as a new diagnostic message of a module through the "DP-RECV" FC just like the other interrupts with this module. You must then read out the individual diagnostics of the slave and evaluate "manually" the sort of message concerned.