The advancement in PLC range of products has blurred the line between PLC and DCS systems and the use of PLCs has now become common for very large installations as well. The availability of wide range of PLCs from vendors and the need to exchange data between these systems has driven the need to development of gateway devices that can act as protocol converters to collect data from one system and deliver to another as per the protocol understood by those systems. Many companies specialize in products that offer the protocol conversion between systems from different vendors. Many OEMS offer their products with modbus protocol enabled to offer remote control / monitoring of their system parameters by other automation control systems. The automation control systems then employ either in-rack or outside converters (gateways) that can understand the modbus signals and convert to make them available to the PLC memory for monitor / control.