software redundancy config

hi all

is ET 200M essential component for hardware configuration in software redundancy configuration(i want to use redundancy in cpu level only)
main system is S7-300

No.

You are probably thinking of the ET200M modules with "active backplanes". These are used when the I/O shall be redundant. It is not related to CPU redundancy.

Apart from that, a prerequisite for CPU redundancy indirectly is that all i/o is handled via DP and not via I/O modules attached to the CPU rack. So that could mean that the I/O is in ET200M (with regular backplane), or ET200S, or something else.

thank you jesper.
i have another question.is cp 343-1 suport modbus TCP/IP?

Mo_eng, you should start another thread.

But anyway, all Siemens current ethernet CPs and CPUs support Modbus TCP, in combination with a library option from Siemens - which costs a license each time.