Modbus® and Modbus Plus™ Communications Protocol

To ensure the life of your architectures over the long term

Schneider Electric offers two open data communications network as the basis for the exchange of information among products on the factory floor:
Modbus® and Modbus Plus™.

Modbus

In a typical Modbus network, Modbus messages are sent over an RS232/RS485 asynchronous serial communication link (EIA standard); e.g., the Modbus-Master initiates a request for information and the Modbus-Slave device responds with the appropriate information sent back. General broadcasts of information are also possible, with no response needed. The two modes of communication within the Modbus network are 10-bit ASCII and 11-bit RTU.

Modbus Plus

In a typical Modbus Plus network, embedded Modbus messages are sent over an RS485 communication link on a peer-to-peer, token-exchange type network. The Modbus Plus networks can be used with Modicon® Quantum™, Momentum™ and Premium™ PLCs.