Here are the supported protocols for Modbus. They are TCP/IP, RTU over TCP/IP, and RTU over RS-485.
The URI setup for each are as follows:
TCP/IP: `modbus-tcp://host/`
RTU over TCP/IP: `modbus-rtutcp://host/`
RTU over RS-485: `modbus-rtu://<port>-<baud>-<dataBits>-<parity>`