Resetting The Watchdog Timer - Mitsubishi Electric MELSEC iQ-R Series Programming Manual

Resetting the watchdog timer

WDT(P)
RnPCPU
RnCPU RnENCPU
(Process)
These instructions reset the watchdog timer.
Ladder
FBD/LD
EN ENO
■Execution condition
Instruction
WDT
WDTP
Processing details
• These instructions reset the watchdog timer in a program.
• These instructions are used when the scan time exceeds the value set for the watchdog timer depending on the condition.
If the scan time exceeds the value set for the watchdog timer every scan, change the watchdog timer value in parameter
using the engineering tool.
• The time values required for t1 from step 0 to the WDT(P) instruction and t2 from the WDT(P) instruction to the END
(FEND) instruction must not exceed the value set for the watchdog timer.
0 step
t1
• The instruction can be used twice or more in a single scan, but it takes time to turn off the output when an error occurs.
• Executing the instruction does not clear the scan time value stored in the special register. For this reason, the scan time
value in the special register may be greater than the value set for the watchdog timer in parameter.
Operation error
There is no operation error.
7 APPLICATION INSTRUCTIONS
554
7.3 Program Execution Control Instructions
RnPCPU RnSFCPU RnSFCPU
(Redundant) (Standard) (Safety)
Execution condition
END (FEND)
WDT
t2
ST
ENO:=WDT(EN);
ENO:=WDTP(EN);