You can install the CP 341 (a single module)on a redundant ET 200M station, slave to a S7-400H. If the active CPU fails and switches over to the standby CPU, the CP 341 (on the redundant ET 200M station) will continue to be read by the S7-400H system,

To setup a CP 341 on a redundant ET 200M you would need:

6ES7153-2AR03-0XA0 ET200M, IM153-2 INTERFACE REDUND.BUNDLE

Includes 2 IM 153-2 and the active bus module required for them;

Plus a special ET 200M redundancy rail (select by the length required):

6ES7195-1GA00-0XA0 ET200M, RAIL 483MM

6ES7195-1GF30-0XA0 ET200M, RAIL 530MM

6ES7195-1GG30-0XA0 ET200M, RAIL 620MM

6ES7195-1GC00-0XA0 ET200M, RAIL 2000MM

Plus active bus modules for the IO modules on the redundant ET 200M rail:

6ES7195-7HB00-0XA0 BUS UNIT F. 2 40MM I/O MODULES

6ES7195-7HC00-0XA0 ET200M, BUS UNIT F. 1 80MM I/O MODULE

6ES7195-7HA00-0XA0 ET200M, BUS UNIT F. PS AND IM 153

And finally, your CP 341-1CH02 (with RS-485 interface).
You would program the CP 341 in the S7-400H program as you would normally do, using the LADDR provided by the HWConfig editor to setuip your communication link to the redundantCPUs.

Hope this helps,

Daniel Chartier

new question is splittet to What if we need redundant Modbus RTU connection, can we use an additional CP341?