in the past, I used a 65cent 8 pin pic, internal clock, only 5v, used the PIC's comparator inputs as a true differential RS485 receiver, and swapped the same 2 comparator analog inputs to output to transmit a balanced differential RS485 output
that's pretty nifty ... however does the comparator has sufficient drive to feed into the terminator resistance. And you would need 4 comparators right? 2for the transmission and another 2 for the reception?
You only need a comparator in reception mode, to transmit RS485, you can just use 2 digital outputs, A RS485 output signal are just 2 digital outputs with 1 with an inverted value of the other. Also, the same 2 balanced wires work in both directions. I know looking at the block diagram of an RS485 transceiver shows this as 2 comparators, and a single cable half-duplex bidirectional unit has the output comparator with an output enable, with it's outputs shorted to the inputs of the receiver. This is the same as in the PIC's software when transmitting you would switch the 2 comparator inputs into digital outputs & drive a +&- version of the serial data on those same 2 pins. If you wanted full duplex RS485, you would keep the comparator input always as inputs and just use 2 additional outputs, always outputing, the +&- USART data.
As for my recommendation, the idea was to simplify one side, just the sensor reader & decoder to generate the digital loop data. The other side would have had a full RS-485 transceiver IC with large MCU using a normal USART. You can always do this MCU internal comparator trick on both sides, but, remember the UART will now be software on both sides & this might not be what you want for your main processor.
Now, with only 1-2meter distance requirement, I personally might even test just test using a terminated TTL signal in a cheap coax cable. The coax would also virtually eliminate emi leaking out during EMC FCC testing. This will allow you to use the built in hardware UART in both MCUs and with Microchip's PIC's +/-50ma drive per IO when operating at 5v, (most of the new PICs), you should be able to drive a terminated cheap coax error free at a megabaud. I would use 1 coax, 1 direction with triple redundant data transmit scheme.
For larger distances, or unshielded twisted pair wiring like network cable, you will have no choice but to use the RS485 method of your choosing to prevent errors.