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I/O Processing Method
3.6.2 Response delay in refresh system
This section describes a delay of an output change in response to an input change.
An output change in response to an input change has a delay of up to two scans as
shown in Fig. 2.6.
Fig 3.7 Output Y Change in Response to Input X Change
Ladder example
When Y1E turns on earliest
The Y1E output turns on earliest when the control input terminal turns from OFF to
ON immediately before a refresh. X5 turns on at an input refresh, Y1E turns on at
step 0, and the control output terminal turns on at an output refresh after execution of
the END instruction.
In this case, therefore, a delay of a control output terminal change in response to a
control input terminal change is one scan.
When Y1E turns on latest
The Y1E output turns on latest when the control input terminal turns from OFF to ON
immediately after a refresh. X5 turns on at the next input refresh, Y1E turns on at
step 0, and the control output terminal turns on at an output refresh after execution of
the END instruction.
In this case, therefore, a delay of a control output terminal change in response to a
control input terminal change is two scans.
In this ladder, output Y1E turns on when input
X5 turns on.
OFF
OFF
OFF
ON
ON
ON
OFF
ON
Input refresh Input refresh Output refresh
0
END END
056 0
(
Minimum 1 scan
)
Control output
terminal
Y1E
X5
Control input
terminal
Delay
OFF
OFF
OFF
ON
ON
ON
OFF
ON
Input refresh Input refresh Output refresh
0
END
END
056 0
Delay
(Maximum 2 scans)
Control output
terminal
Y1E
X5
Control input
terminal