4.
AZCCPU
/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 setting, a
WDT
error
might
occur.
The relationship between the constant scan time setting
and the watch dog timer setting is indicated below.
0
<
Constant scan time setting
d
WDT 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.
Scan in which constant scan is not executed
correctly
be
cor.
mw,
constant
scan
rectly
in the succeeding
scan
I
Fig.
4.12
Scan
lime
Largo#
than
Conrtrnt
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.
R
1
.d
1
U