Modbus is an open communications protocol originally developed in 1978 by Modicon Inc. for networking industrial PLCs (programmable
logic controllers). (Modicon is now an international brand of Schneider Electric.) Since its introduction, it has gained popularity
with a number of control device vendors to transfer discrete/analog I/O and register data between control devices.
While the type of Modbus network and the devices it supports change depending on the technology (serial or TCP/IP), and the
purpose of the network and devices change based on their roles as client or server (slave), the driver procedures for setting
up networks, devices and points are basically the same.