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Ethernet Global Data Protocol
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<p>Ethernet Global Data (EGD) is a protocol that enables producer (server) to share a portion of its memory to all the consumers (clients) at a scheduled periodic rate. This protocol is developed for <a href="/facts/GE_Fanuc_Automation_North_America%2c_Inc./hD0CY1Jr">GE Fanuc</a> <a href="/facts/Programmable_logic_controller/bqh0GAdb">PLCs</a> to exchange data between PLCs / Drive Systems / HMI/SCADA systems. The protocol uses <a href="/facts/User_Datagram_Protocol/dxLU0D6q"> UDP</a> over <a href="/facts/Ethernet/nMfhU8tU">Ethernet</a> layers for exchanging the data. A snapshot of internal reference memory, mediated by an <a href="/facts/Ethernet/nMfhU8tU">Ethernet</a> interface, is referred to as an exchange. An exchange does not require a reply and is identified by a unique combination of three major identifiers. </p> <ul><li>The Producer ID (the producer's IP address)</li> <li>The Exchange ID (the exchange's identifier)</li> <li>The Adapter Name (the Ethernet interface identifier)</li></ul> <p>EGD is implemented using classes. </p> <ul><li>Class 0 - supports configured exchanges only (implemented in most PACSystems CPUs)</li> <li>Class 1 - supports all class 0 services plus programmed EGD exchanges that can be used to read and write other devices on an ad-hoc basis</li> <li>Class 2 - supports all class 1 services plus acts as a responder for programmed EGD exchanges (implemented by Ethernet interface module only)</li> <li>Class 3 - supports all class 2 services plus static configuration from an EGD configuration server</li> <li>Class 4 - supports all class 3 services plus dynamically bound configuration from an EGD configuration server</li></ul>