4.
A2ccPtl
/MELSEC-A
4.1.7
Scan
time
(1) Scan time
Scan time is the period in which PC one scan
[O
to
ml
(FEND)] is executed.
I
I-
Scan time
CI
END
0
END
0
L
Sequence program
Processing of counters and timers
Self-diagnosis check
I
Fig.
4.6
Scan
lime
(2)
Scan time confirmation
The A2CCPU counts
the
scan time between an
-1
(FEND)
instruction to the next
ml
(FEND) instruction and registers
the counted Scan time in special registers 09017 to D9019.
1) Special register data (09017 to D9019)
09017
.........
The minimum scan time
.
D9018
.........
Present scan time
D9019
.........
The maximum scan time
2)
Accuracy of scan time
The accurate to scan time counted by the programmable
controller is accurate to
+lo
ms.
Therefore, if the data in D9017 to D9019 is
5,
actual scan
time
is
in the range of
40
to
60
ms.
3)
The data in D9017 to D9019 is not cleared when the
instruction is executed; the scan time between an
(FEND) instruction and the next
m]
(FEND) instruction is
registered.
1)
The scan time can be confirmed by the circuit monitoring operation using a
peripheral device.
Scan time of
0
to
20
ms
.........
10
ms is displayed
Scan time of
10
to
30
ms
.........
20
ms is displayed
2)
The constant scan function allows the scan time
of
every scan to be fixed to a
constant value. For more details on the constant scan function, see
4.2.1.
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