siemens 315 2DP software redundant

Hi,

I'm new to software redundancy. I have two 315 2DP Cpu's that should connect to two IM 153-2's. I have 8 I/O modules that I would like to place next to the two IM153-2's on the same rack. But is this possible? Now I have IM|IM|DI|DI|DO|DO|AI|AI|AI|AO, but only the second IM is running well, the first IM in the rack goes into failure.
I can't find much on the siemens website, maybe I'm looking in the wrong places?

Thanks for helping!
Hendrik

Do you use the special active backplanes for this and the special couplemodule for the IM cards (or IM redundancy bundle).
Otherwise the hardware config is not exactly the same. Copy the complete racks from cpu a to cpu b in the hardware config. One minor difference between both gives trouble.
Also check your program, or is the profibus not running from cpu B not running?
There is a small doc format manual delivered with the software redundancy software or from siemens.com. Very important is to do the redundancy programming within the OB35 call in the program, as described.
If you change the settings (in/out) of the special function blocks, delete online the 3 generated datablocks before putting the cpu back into run. These datablocks are generated automatically when starting the software redundant cpu for the first time.