Modbus RTU / TCP
One of the oldest and most widely deployed industrial protocols: from serial communications (RTU/ASCII) to Ethernet (TCP).
Modbus is the world's most widely used industrial communication protocol. Developed in 1979, it remains fundamental in communication between PLCs, variable frequency drives, sensors and SCADA systems. Available in three variants: Modbus RTU (binary serial), Modbus ASCII (text serial) and Modbus TCP/IP (Ethernet).