32 channel analog control of RS485 device over 2-wire
RS485 channel 2 makes no sense. RS485 is a communications standard and doesn't care about the data content transmitted or what comes out of the RS485 interfaces so "channel 2" makes no sense in your question. 

You need to state what the data and packaging is for this to be answered fully but, as a short answer use a regular MCU like a PIC and write some code that reads the 32 switches and outputs a serial stream (converted to RS485 format) that corresponds to the input serial stream requirements on the remote battery powered device.