GE GFK-1004B Manuel D’Utilisation

4-11

GFK-1004B

Chapter 4 Programming Communications Requests

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 %R50-%R57 to local PLC
registers %R100-%R107. Repeat the read 10 times once every 7 seconds with a timeout
of 500 ms for each read.

ÁÁÁÁÁ

ÁÁÁÁÁÁ

Dec (Hex)

ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ

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Word 1

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00017 (0011)

ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ

Length of Channel Command Data Block (17 - 25 words)

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Word 2

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00000 (0000)

ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ

Always 0 (no-wait mode request)

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Word 3

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00008 (0008)

ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ

Memory type of CRS word (%R)

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Word 4

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00009 (0009)

ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ

CRS word address minus 1 (%R10)*

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Word 5

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00000 (0000)

ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ

Reserved

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Word 6

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00000 (0000)

ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ

Reserved

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Word 7

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02003 (07d3)

ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ

Establish Read Channel Command number

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Word 8

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00005 (0005)

ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ

Channel number (5)

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Word 9

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00010 (000A)

ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ

Number of read repetitions (read 10 times)

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Word 10

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00003 (0003)

ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ

Time units for read period (3=seconds)

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Word 11

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00007 (0007)

ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ

Number of time units for read period (every 7 seconds)

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Word 12

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00050 (0032)

ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ

Timeout for each read (500 ms)

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Word 13

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00008 (0008)

ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ

Local PLC - memory type at which to store data (%R)

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Word 14

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00100 (0064)

ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ

Local PLC - starting address at which to store data (%R100)

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Word 15

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00008 (0008)

ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ

Remote PLC - memory type from which to read data (%R)

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Word 16

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00050 (0032)

ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ

Remote PLC - starting address from which to read data (%R50)

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Word 17

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00008 (0008)

ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ

Remote PLC - number of memory units (8 registers)

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Word 18

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00001 (0001)

ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ

Remote PLC - PLC (node) address type (IP Address)

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Word 19

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00004 (0004)

ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ

Remote PLC - PLC (node) address length in words (4)

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Word 20

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00003 (0003)

ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ

Remote PLC - Register 1 of IP address (3)

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Word 21

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00000 (0000)

ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ

Remote PLC - Register 2 of IP address (0)

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Word 22

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00000 (0000)

ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ

Remote PLC - Register 3 of IP address (0)

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Word 23

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00001 (0001)

ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ

Remote PLC - Register 4 of IP address (1)

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Word 24 - 27

ÁÁÁÁÁÁ

ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ

Remote PLC - Program Name (needed for access to remote %P
or %L) (zero terminated and padded)

ÁÁÁÁÁ

Word 28 - 31

ÁÁÁÁÁÁ

ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ

Remote PLC - Program Block (needed for access to remote %L)
(zero terminated and padded)

* Word 4 (CRS word address) is the only zero-based address in the Command Block.

Only this address requires subtracting 1 from the intended address.

(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.

The term local PLC is
used here to identify the
client PLC

-the PLC

that initiates the
communications
request.

The term remote PLC
is used here to identify
the server PLC-the
PLC that responds to
the request.