SLC redundancy with 2 BSN

[TEJ 0]

Hi Guys, I'm doing a project with SLC Redundancy system, where 36 RIO modules were used. Since the Complementry mode cannot be used with ASB's (No. of Input & Output modules were not same), so i've no other options and yes 2 BSN's. Is anybody worked with this configuration please help me on how to configure the BSN module. And how to use the M files of the second BSN. Rockwell Manuals also not provide enough details in this mode. Also I'[m going to place another Modbus module in the redundant chassis (i think it is 1747-BAS) for Compressor data communication. Is anybody worked on this?? Is there any sample code available for the Modbus communications?? Thanx in Advance