I am replacing a 25 pushbutton operator's station that controls both a time lapse VCR and a digital multiplexer tied to 4 cameras. The pushbuttons currently switch in a resistive ladder network to contol the VCR and the mux. Originally I was going to use an md888 to switch in the correct ohm value, but I discovered tha both devices thru rs485 ports support a Sanyo Protocol called Security Serial Protocol. I have the command set from the Sanyo manuals and would like to use the plc to issue the command sequences both don't have any solid ideas about how this proprietary protocol and the command set interrelate. Any ideas? Where can I find some material about rolling in a protocol to the plc?
I also thought about a 0-20 ma signal to fool the analog ports of the two boxes but the plc output doesnt have enough resolution
thanks
raan