How to monitor modbus?

[admin]

You can use any USB-RS485 converter, you just need to know the baudrate, stop bits and parity. For serial data monitoring you can use RealTerm https://sourceforge.net/projects/realterm/, it has an option to display binary data in HEX. Then you can use this online tool to parse ModBus request/response: http://modbus.rapidscada.net/

You can also connect RS485 to LM an write a simple script to log incoming data.