Work in progress, Modbus driver using the Mesa PktUART
Note that for RS485 the Mesa Rx and TX lines need to be connected + to + and - to - at the FPGA board. Also, the polarity is inverted, Modbus A+ goes to Tx/Rx- and B- to Tx/Rx+
Compile / install with halcompile --install mesa-modbus.c To run the test setup with a 4-relay modbus card halrun -I modbus.hal