Where is Modbus TCP/IP used?

Modbus TCP/IP has become ubiquitous because of its openness, simplicity, low-cost development, and minimum hardware required to support it. There are several hundred Modbus TCP/IP devices available in the market - more being developed each year. It is used to exchange information between devices, monitor, and program them. It is also used to manage distributed I/Os, being the preferred protocol by the manufacturers of this type of devices.