Hello, I felt like having a go at designing the Raspberry Pi HAT. It was my first time making an organized schematic and also using 3D modeling so it was a good learning experience!Custom Board - I would really now like to make a custom raspberry pi hat which will have the RS485 converter, sense line circuit etc. on one simple board that people can just plug onto their Pi. I'm thinking that using the onboard RS232 the pi has might make this work with raspberry pi 1s which are cheaper. If anyone is interested in helping with making the boards, I'd be really interested to have someone help me design them.
This is is the diagram I followed for my sense line implementation in MEGA JVS, and it has always worked. IIRC, I use a 10k ohm resistor, to sink the transistor.