Mitsubishi Electric MELSEC Q Series User Manual page 161

(1) Conditions for watchdog timer time out
• System watchdog timer
Times out when the system processing has been suspended for a long time, for reasons such as C
Controller module hardware error and interrupt program execution, etc.
• User watchdog timer
Times out when the system processing has been suspended for a long time, for reasons such as C
Controller module hardware error and interrupt program execution, etc.
Further, it also times out when the user program cannot complete processing within the time specified by the
C Controller module dedicated function (CCPU_StartWDT function) and cannot execute the C Controller
module dedicated function (CCPU_ResetWDT function).
(2) When a watchdog timer times out
When a watchdog timer times out, a watchdog timer error is detected and the following conditions occur.
• The C Controller module turns off all the outputs.
• The RUN LED turns off, and the ERR.LED flashes.
Only for a system watchdog timer error, the MODE LED also turns off.
• An abnormal completion (WDT error) is detected when the C Controller module dedicated function is used.
(3) Setting a watchdog timer
• System watchdog timer
Can be set and changed in the range of 20ms to 2000ms (in increments of 10ms) in Project view  "Parameter"
 "CCPU Parameter"  <<RAS settings>> in
(The default is 1000ms.)
• User watchdog timer
Can be set and changed in the range of 100ms to 10000ms (in increments of 10ms) in Project view 
"Parameter"  "CCPU Parameter"  <<RAS settings>> in
(The default is 1000ms.)
● For setting of the user watchdog timer by the user program
Each timer can be set and changed by using the C Controller module dedicated function (CCPU_StartWDT function)
after deselecting the Project view  "Parameter"  "CCPU Parameter"  <<RAS
checkbox in Setting/monitoring tools for the C Controller module.
(4) Resetting a watchdog timer
• System watchdog timer
The system watchdog timer is periodically reset in the C Controller module.
• User watchdog timer
The user watchdog timer is periodically reset in the C Controller module.
● For resetting of the user watchdog timer by the user program
Use the C Controller module dedicated function (CCPU_StartWDT function) to start monitoring and the C Controller
module dedicated function (CCPU_ResetWDT function) to reset the timer.
For "-LS", consult with the
partner (operating system vendor).
etting/monitoring tools for the C Controller module.
S
For "-LS", consult with the
partner (operating system vendor).
For "-LS", consult with the
partner (operating system vendor).
CHAPTER 11 BASIC FUNCTIONS
etting/monitoring tools for the C Controller module.
S
For "-LS", consult with the
partner (operating system vendor).
s ettings>>  "Use user WDT"
For "-LS", consult with the
partner (operating system vendor).
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