GE GFK-1541B manual Overview of EGD, Configuring the Exchange

5

Overview of EGD

This section describes Ethernet Global Data in general terms. It also provides key information you need to plan and configure your Ethernet Global Data system.

Ethernet Global Data allows one device (the producer) to share a portion of its internal memory (the exchange) with one or more other devices (the consumers) at a regularly scheduled periodic rate. This exchange is uniquely distinguished by a set of identifiers, the Producer ID and Exchange ID. The Producer ID is assigned to uniquely identify the Ethernet Global Data device that produces the exchange on the network. The Exchange ID is a value identifying a specific exchange within that producing device.

Ethernet Global Data is configured using Windows-based PLC programming software (if supported).

PLC1 - Producer PLC2 - Consumer

P

C

Exchange

Caution

Ethernet Network

Ethernet Global Data is designed for simple, efficient communication of sampled data between devices. It is not intended for event notification where the possible loss of a sample of data would be significant. For event notification, it is recommended that an Establish Read/Write Channel command be used. See Chapter 3, “Programming SRTP Channel Commands”, for more information.

Note

A single Ethernet Interface can be configured to both produce and consume

Ethernet Global Data at the same time, using separate exchanges.

Exchange

The exchange refers to a set of variables or memory locations that contain an internal snapshot of memory within the PLC or other device. The Exchange ID is the value you assign to a particular exchange that identifies it uniquely within a particular producer. You must configure an exchange in both the producer and the consumer.

Configuring the Exchange

Exchanges are configured by filling out parameters in the Ethernet Global Data dialog box of the PLC programming software for both the producer PLC and consumer PLC and then storing each configuration to its associated PLC. These parameters define the content of an exchange as well as its operational characteristics. A variable that has already been created in hardware configuration, the program editors, or the Variable Declaration Editor window can be used in an exchange. Or, you can create new variables in the Ethernet Global Data dialog box.

5-2 TCP/IP Ethernet Communications for the Series 90™ PLC User's Manual– May 2002 GFK-1541B