Read Plc Memory (4000); Read Plc Memory Command Block - GE RX3i User Manual

Chapter 6. Programming EGD Commands

Read PLC Memory (4000)

6.5
The Read PLC Memory command can be used to read memory locations from a remote PACSystems PLC. This
command does not require configuration of a produced / consumed exchange in the PLCs. The Read PLC
Memory command can only be sent to an individual IP Address; it cannot be sent to a Group ID (multicast).

Read PLC Memory Command Block

Word Offset Value
Word 1 Length of command data block
Word 2 0
Word 3 (See previous page)
Word 4 0-based
Word 5 0
Word 6 0
Word 7 4000 (fa0H))
Word 8 Retry time, in milliseconds
Word 9 Local read buffer memory type
Word 10 Local read buffer reference table
starting address (least significant
word)
Word 11 Local read buffer reference table
starting address (most significant
word)
Word 12 Remote read location memory type
Word 13 Remote reference table read
location starting address (least
significant word)
Word 14 Remote reference table read
location starting address (most
significant word)
Word 15 Remote reference table length (in
remote memory units)
Word 16 Network address type
Word 17 Network address length
Word 18 – IP Address of the remote PLC
Word 21
Word 22 Reserved
Word 4 (COMMREQ status word address) is the only zero-based address in the Command Block. This value
13
alone requires that 1 be subtracted from the intended address.
96 PACSystems* RX7i & RX3i TCP/IP Ethernet Communications User Manual
13
Description
Always 16
Always 0 (no-wait mode request)
Memory type of COMMREQ Status Word
Offset of COMMREQ Status Word
Reserved
Reserved
Read PLC Memory command number.
The time between retries of command transfers. Default
is 1000ms.
Memory type for the data to be placed in the local PLC.
1-based offset in the local PLC
Memory type from which data will be read in the remote
PLC
1-based offset in the remote PLC
Number of remote memory units to be read.
Must be 1. Indicates an IP address will be used.
Must be 4 for IP address.
Group ID (multicast) is not permitted.
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.
Always 0
GFK-2224Q