Do you think it's actually RS-485 comms? Over the two contact connections? If I remember right, those are the pins it uses to communicate with DC fast chargers, but I also think it's a PLC protocol. Very confusing for someone who works in the industrial world, because PLC means programmable...
I know it says PSI for the unit of measurement, but assuming your tire pressure is around 43 PSI, those units are in kPa. Which would put the conversion at 1 kPa = 0.145038 PSI.
First off, I'm excited to mess with this to get my truck into Home Assistant, since that's pretty awesome. Agreed with everyone's frustration with Yaml, as it's my least favorite part of the whole thing. But the main reason I'm commenting is to talk about your Modbus integration with the Home...