Chapter 6. Programming EGD CommandsGFK-2224Q January 2017 1016.7 Read EGD Exchange (4002)The Read EGD Exchange command can be used to read some or all of a configured Ethernet Global Dataexchange from either the producer or the consumer. This command identifies the data to be read using itsconfigured Producer ID and Exchange ID. It can then read the content of the data for the exchange, directlyfrom the producer or consumer device memory. This command can be sent to PACSystems PLCs and to otherEGD Class 2 devices. In a PACSystems PLC, reading an EGD exchange reads the PLC reference memorylocations configured to be transferred at the specified offset in the exchange. Thus current process data will beread, not the data that was transferred last in the exchange.Read EGD Exchange Command BlockWord Offset Value DescriptionWord 1 Length of command data block Always 19Word 2 0 Always 0 (no-wait mode request)Word 3 (See table on page 95) Memory type of COMMREQ Status WordWord 4 0-based 13 Offset of COMMREQ Status WordWord 5 0 ReservedWord 6 0 ReservedWord 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 startingaddress (least significant word)1-based offsetWord 11 Local read buffer reference table startingaddress (most significant word)Word 12 Remote signature EGD Exchange signature. This should be 0 forPLCs when not using signatures. If run-mode storeof EGD will be used, the use of signatures is highlyrecommended.Word 13 Remote Producer ID (least significant word) EGD Producer IDWord 14 Remote Producer ID (most significant word)Word 15 Remote Exchange ID (least significantword)EGD Exchange IDWord 16 Remote Exchange ID (most significantword)Word 17 Remote Exchange Offset Byte offset (0-based) in the exchange that shouldbe read.Word 18 Read length Number of bytes to be read in the range 0 to 1400bytes.Word 19 Network address type Must be 1. Indicates that an IP address will beused.Word 20 Network address length Must be 4 for IP address. Group ID (multicast) isnot permitted.Word 21 toWord 24IP Address of the remote PLC Four integers, specified as one integer per word ofthe dotted-decimal IP address of the remote PLC.May not be a group IP address.Word 25 Reserved Always 0
