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Establish Read Channel (2003)
The Establish Read Channel Command requests that a channel be associated with a remote PLC and that data from the remote PLC be transferred (periodically) to the local PLC. The Command Block specifies the period, the number of reads from the remote to perform, and the timeout allowed in waiting for each transfer to complete. The first read is performed immediately, regardless of the period specified.
Example Command Block
Establish a channel (channel 5) to a remote PLC at IP address 3.0.0.1. Return the COMMREQ Status word to %R10. Read remote PLC registers
The term local PLC is used here to identify the
The term remotePLC is used here to identify the
| Dec | (Hex) |
|
Word 1 | 00017 | (0011) | Length of Channel Command Data Block (17 - 25 words) |
Word 2 | 00000 | (0000) | Always 0 |
Word 3 | 00008 | (0008) | Memory type of CRS word (%R) |
Word 4 | 00009 | (0009) | CRS word address minus 1 (%R10)* |
Word 5 | 00000 | (0000) | Reserved |
Word 6 | 00000 | (0000) | Reserved |
Word 7 | 02003 | (07d3) | Establish Read Channel Command number |
Word 8 | 00005 | (0005) | Channel number (5) |
Word 9 | 00010 | (000A) | Number of read repetitions (read 10 times) |
Word 10 | 00003 | (0003) | Time units for read period (3=seconds) |
Word 11 | 00007 | (0007) | Number of time units for read period (every 7 seconds) |
Word 12 | 00050 | (0032) | Timeout for each read (500 ms) |
Word 13 | 00008 | (0008) | Local PLC - memory type at which to store data (%R) |
Word 14 | 00100 | (0064) | Local PLC - starting address at which to store data (%R100) |
Word 15 | 00008 | (0008) | Remote PLC - memory type from which to read data (%R) |
Word 16 | 00050 | (0032) | Remote PLC - starting address from which to read data (%R50) |
Word 17 | 00008 | (0008) | Remote PLC - number of memory units (8 registers) |
Word 18 | 00001 | (0001) | Remote PLC - PLC (node) address type (IP Address) |
Word 19 | 00004 | (0004) | Remote PLC - PLC (node) address length in words (4) |
Word 20 | 00003 | (0003) | Remote PLC - Register 1 of IP address (3) |
Word 21 | 00000 | (0000) | Remote PLC - Register 2 of IP address (0) |
Word 22 | 00000 | (0000) | Remote PLC - Register 3 of IP address (0) |
Word 23 | 00001 | (0001) | Remote PLC - Register 4 of IP address (1) |
Word 24 - 27 |
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| Remote PLC - Program Name (needed for access to remote %P |
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| or %L) (zero terminated and padded) |
Word 28 - 31 |
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| Remote PLC - Program Block (needed for access to remote %L) |
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| (zero terminated and padded) |
*Word 4 (CRS word address) is the only
(Word 7) Channel Command Number: Word 7 requests that a read channel be set up. If the command is processed successfully, it will result in attempting the specified number of transfers from the server to the client.
Chapter 4 Programming Communications Requests |