GE PACSystems RX7i, User Manual

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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
Word Offset Value Description
Word 1 Length of command data block Always 19
Word 2 0 Always 0 (no-wait mode request)
Word 3 (See table on page 95) Memory type of COMMREQ Status Word
Word 4 0-based
13
Offset of COMMREQ Status Word
Word 5 0 Reserved
Word 6 0 Reserved
Word 7 4002 (fa2H) Read EGD Exchange command number.
Word 8 Retry time, in milliseconds The time between retries of command transfers,.
Default is 1000ms.
Word 9 Local read buffer memory type Memory type for the data, in the local PLC.
Word 10 Local read buffer reference table starting
address (least significant word)
1-based offset
Word 11 Local read buffer reference table starting
address (most significant word)
Word 12 Remote signature EGD Exchange signature. This should be 0 for
PLCs when not using signatures. If run-mode store
of EGD will be used, the use of signatures is highly
recommended.
Word 13 Remote Producer ID (least significant word) EGD Producer ID
Word 14 Remote Producer ID (most significant word)
Word 15 Remote Exchange ID (least significant
word)
EGD Exchange ID
Word 16 Remote Exchange ID (most significant
word)
Word 17 Remote Exchange Offset Byte offset (0-based) in the exchange that should
be read.
Word 18 Read length Number of bytes to be read in the range 0 to 1400
bytes.
Word 19 Network address type Must be 1. Indicates that an IP address will be
used.
Word 20 Network address length Must be 4 for IP address. Group ID (multicast) is
not permitted.
Word 21 to
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.
Word 25 Reserved Always 0