Relay Gateways & Proxies

Relays are switches that open and close circuits. They control one electrical circuit by opening or closing contacts in another circuit. When a relay contact is normally open (NO), there is an open contact when the relay is not energized. When a relay contact is normally closed (NC), there is a closed contact when the relay is not energized. Applying electrical current to the contacts will change their state. Many relays use an electromagnet to mechanically operate a switch, but other operating principles such as solid-state relays are also used. Relays are used where it is necessary to control a circuit by a low-power signal or where several circuits must be controlled by one signal. Depending on the structural features and operating principle, relays are of different types such as monitoring, regulating, auxiliary and protective. Classification of the types of relays depend on the function for which they are used. 

A gateway is a hardware device that joins two networks so that devices on one network can communicate with devices on another network. It serves as an entry and exit point for a network as all data traffic passes through it before being routed. Ethernet gateways are devices that allow protocol conversion to an EtherNet/IP network. In automated industrial or SCADA (Supervisory Control and Data Acquisition) systems, Ethernet gateways often facilitate connecting serial devices to an Ethernet network, allowing multiple connections and a conversion between fieldbus protocols such as Modbus or PROFIBUS (Process Filed Bus) to EtherNet/IP or PROFINET (Process Field Net).