Chapter 6. Programming EGD CommandsGFK-2224Q January 2017 996.6 Write PLC Memory (4001)The Write PLC Memory command can be used to write memory locations to one remote PACSystems PLC. Useof this command does not require a configured produced / consumed exchange in the PLCs.Write PLC Memory Command BlockWord Offset Value DescriptionWord 1 Length of command data block Always 16Word 2 0 Always 0 (no-wait mode request)Word 3 (See table on page 95) Memory type of COMMREQ Status WordWord 4 0-based13 Offset of COMMREQ Status WordWord 5 0 ReservedWord 6 0 ReservedWord 7 4001 (fa1H) Write PLC Memory command number.Word 8 Retry time, in milliseconds The time between retries of command transfers.Default is 1000ms.Word 9 Local write buffer memory type Memory type for the data that will be written, in thelocal PLC.Word 10 Local write buffer reference tablestarting address (least significant word)1-based offset in the local PLC.Word 11 Local write buffer reference tablestarting address (most significant word)Word 12 Remote write location memory type Memory type into which data will be written in theremote PLC(s)Word 13 Remote reference table write locationstarting address (least significant word)1-based offset in the remote PLCWord 14 Remote reference table write locationstarting address (least significant word)Word 15 Write Length 0 to 1400 bytes, 0 to 700 words.Word 16 Network address type Must be 1. Indicates an IP address will be used.Word 17 Network address length Must be 4 for IP address.Group ID (multicast) is not permitted.Word 18 –Word 21IP 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 22 Reserved Always 0(Word 7) EGD Command Number: Word 7 a write PLC memory operation. If the command is processedsuccessfully, it will result in PLC reference memory data being sent from the server to the client.(Word 8) Command Retry Time: Word 8 specifies the time (in milliseconds) the Ethernet Interface will waitbetween retries when transferring the command. A total of four tries will be made to send the command. If noresponse is received after the four tries (i.e. after four times the retry time value), an error status will be returnedin the COMMREQ status word. If the command retry is specified as zero, the default value of one second is used.(Word 9) Local PLC - Memory Type: Words 9-11 specify the location in the local PLC where the EthernetInterface will get the data to be written to the remote PLC. Valid values for Word 9 are listed in the descriptionof Read PLC Memory Command. The amount of data to be transferred is specified by the number of memoryunits of the data written to the remote PLC (Word 15).(Words 10 - 11) Local PLC - Memory Starting Address: Words 10 and 11 determine the starting address in thelocal PLC from which the data is to be written to the remote PLC. The value entered is the 32-bit offset (1-based)
