Mitsubishi Electric Melsec A Series - Page 56

4.A2CCPU
-------------------- MELSEC·A
(b) The watch dog timer setting must be greater than the constant scan
time setting.
If
the watch dog timer setting is smaller than the constant scan time I
setting, a WOT error might occur.
The relationship between
the constant scan time setting and the
watch dog timer setting is indicated below.
o< Constant scan time setting < WOT setting -1
(c) The set constant scan time must be greater
than the maximum scan
time of the sequence program.
If the sequence program scan time is
longer than the constant scan
time, the constant scan function is not performed correctly.
Constant
scan
Sequence
program
Constant scan setting
I I
0
10 20 30 40
10 20
30 40
10 20
30 40 10 20
I
I I I I
I
I I I
I I
I I I I
END 0
END
0
H-I
H HI Hf-
35 msec
I
5 mseo
35 msee
34 msee
I
8m
I
37 msec
2
eo 40 meec
40 msee
53 msec
sec
Scan in which c10nstant scan is
not executed correctly
Fig. 4.12 Scan Time Larger than Constant Scan Setting
(2) Setting for constant scan execution
(a) Constant scan execution
A constant scan time setting is written to
09020 using the sequence
program or
the peripheral device.
(b) Constant scan not executed
The value
"0' is written to 09020 using the sequence program or
the peripheral device.
4-20
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