Mitsubishi MELSEC-A series, Programming Manual

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7. APPLICATION INSTRUCTIONS
7
−
122
MELSEC-A
7.10.1 WDT reset
(WDT, WDTP)
Available Device
Bit device Word (16-bit) device Constant Pointer Level
Ca
rr
y
fla
g
Err
o
r
fla
g
X Y M L S B F T C D W R A0 A1 Z V K H P I N
D
igit specification
In
d
e
x
M9012 (M9010, M9011)
Functions (1) Resets the watch dog timer in a sequence program.
(2) Used when the period of time from step 0 to END (FEND) in the sequence
program exceeds the set value of watch dog timer depending on conditions. If
the scan time exceeds the set value of watch dog timer at every scan, change
the set value of watch dog timer by the parameter setting of peripheral
equipment (A6GPP, A6PHP, A6HGP, A7PU).
(3) Set the set value of the watch dog timer so that "t1" from step 0 to WDT
instruction and "t2" from the WDT to END (FEND) instruction do not exceed the
set value. (See the diagram below.)
(4) The WDT instruction can be used two or more times during one scan. However,
care should be exercised because, if error occurs, the outputs cannot be turned
off immediately.
Applicable
CPU
All CPUs
WDT
WDTP
WDT reset commands