Ethernet Global Data Protocol
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 GE Fanuc PLCs to exchange data between PLCs / Drive Systems / HMI/SCADA systems. The protocol uses UDP over Ethernet layers for exchanging the data. A snapshot of internal reference memory, mediated by an Ethernet 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.
- The Producer ID (the producer's IP address)
- The Exchange ID (the exchange's identifier)
- The Adapter Name (the Ethernet interface identifier)
EGD is implemented using clases.
- EGD class 1 is cyclical data where the application determines the data content
- EGD class 2 adds to class 1 with acyclical, programmed messages
- EGD class 3 adds to class 2 with a fixed configuration server that defines the message content
- EGD class 4 adds to class 3 with dynamically bound configuration
Most GE (now Emerson) PLCs support EGD class 1.
GE no longer publishes the EGD protocol due to cyber security issues.