Chapter 6. Programming EGD Commands
GFK-2224Q January 2017 101
6.7 Read EGD Exchange (4002)
The Read EGD Exchange command can be used to read some or all of a configured Ethernet Global Data
exchange from either the producer or the consumer. This command identifies the data to be read using its
configured Producer ID and Exchange ID. It can then read the content of the data for the exchange, directly
from the producer or consumer device memory. This command can be sent to PACSystems PLCs and to other
EGD Class 2 devices. In a PACSystems PLC, reading an EGD exchange reads the PLC reference memory
locations configured to be transferred at the specified offset in the exchange. Thus current process data will be
read, not the data that was transferred last in the exchange.
Read EGD Exchange Command Block
Length of command data block
Always 0 (no-wait mode request)
Memory type of COMMREQ Status Word
13
Offset of COMMREQ Status Word
Read EGD Exchange command number.
Retry time, in milliseconds
The time between retries of command transfers,.
Default is 1000ms.
Local read buffer memory type
Memory type for the data, in the local PLC.
Local read buffer reference table starting
address (least significant word)
Local read buffer reference table starting
address (most significant word)
EGD Exchange signature. This should be 0 for
PLCs when not using signatures. If run-
of EGD will be used, the use of signatures is highly
Remote Producer ID (least significant word)
Remote Producer ID (most significant word)
Remote Exchange ID (least significant
word)
Remote Exchange ID (most significant
word)
Byte offset (0-based) in the exchange that should
be read.
Number of bytes to be read in the range 0 to 1400
bytes.
Must be 1. Indicates that an IP address will be
used.
Must be 4 for IP address. Group ID (multicast) is
not permitted.
Word 24
IP Address of the remote PLC
Four integers, specified as one integer per word of
the dotted-decimal IP address of the remote PLC.
May not be a group IP address.
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