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10
DEDICATED INSTRUCTIONS
Function
[Operation for MBREQ instruction execution]
Sequence program
MBREQ instruction
Completion device
(D2)
Completion status
indication device
(D2) + 1
10 - 15
(1)
To the slave specified by the Target IP address of the control data, the request
message can be sent using any given PDU (protocol data unit) format.
(2)
A maximum of eight MBREQ instructions can be executed simultaneously.
Any instructions attempted in excess of the limit are ignored.
Create a sequence program so that the number of simultaneously executed
MBREQ instructions does not exceed 8.
(3)
The QJ71MT91 automatically opens a TCP connection with a target slave when
this instruction is executed.
(4)
Whether TCP connection closing processing is performed or not can be selected
in "Execution type ((S1)+0)" of the control data.
When communication with the same target device is made frequently using the
dedicated instruction, setting "TCP connection is not closed after instruction
completion" saves the time required for TCP connection opening for the
subsequent instruction execution.
(5)
Whether the MBREQ instruction is being executed or not and whether it is
completed normally or not can be confirmed in the completion device (D2) and
completion status indication device ((D2)+1) specified in the set data.
(a)
Completion device (D2)
Turns ON in the END processing of the scan where the MBREQ instruction
is completed, and turns OFF in the next END processing.
(b)
Completion status indication device ((D2)+1)
Turns ON/OFF depending on the status of the MBREQ instruction
completion.
Normal completion:
Error completion :
END
END
processing
processing
ON
OFF
OFF
OFF
Remains OFF.
Turns ON in the END processing of the scan where
the MBREQ instruction is completed, and turns OFF
in the next END processing.
Completion of MBREQ
instruction execution
MELSEC-Q
END
END
processing
processing
ON
Error
ON
completion
Normal
completion
1 scan
10 - 15
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