Open communication protocol based on Master-Slave architecture. MODBUS Protocol © is a messaging framework widely used to establish master-slave communication between intelligent devices
A MODBUS message sent from the master to the slave contains the address of the slave, the “command” (e.g. “read register” or “write register”), the data, and a checksum (LRC or CRC).
Since the Modbus protocol is just a messaging framework, it is independent of the underlying physical layer. It is traditionally implemented using RS232, RS422 or RS485.