Chapter 27 Watchdog Timer Function - Mitsubishi Electric MELSEC iQ-R Series User Manual

27
WATCHDOG TIMER FUNCTION
This function monitors and detects a bus control failure using the watchdog timer (WDT) and notifies an error if the failure
occurs. The watchdog timer (WDT) is an internal timer of this product.
• The function does not monitor for Windows in this product.
• It does not affect the operation of Windows. However, a Windows service that uses the MELSEC functions
of this product may not operate properly.
Monitoring time setting
Set the monitoring time for the watchdog timer.
[CPU Parameter]  [RAS Setting]  [WDT (Watchdog Timer) Setting]  [System WDT Setting]
Window
Displayed items
Item
Monitoring time
Watchdog timer error (timeout of the watchdog timer)
If system processing is suspended for a long time because of a hardware failure, etc., the watchdog timer cannot be reset and
timeout will occur.
When the watchdog timer times out, an error indicating that the monitoring time set in the WDT (watchdog timer) setting has
been exceeded (watchdog timer error) occurs.
■State of this product
If an error occurs, this product will be in the following state.
Item
LED status
Output
User program
27 WATCHDOG TIMER FUNCTION
204
Description
Set the monitoring time of the system WDT.
Description
LED statuses change to as follows:
• READY LED: OFF
• ERROR LED: ON (red)
• Y STOP LED: ON (orange)
The statuses of other LEDs do not change.
This product is in the Y STOP state.
The Y output status follows the output mode setting when the status is changed from Y STOP to Y OUT. (Page
197 Y OUTPUT CONTROL FUNCTION)
A user program does not stop.
However, an error is returned when executing the following functions:
• mdBdDevSetEx function
• mdBdDevRstEx function
• mdBdSendEx function
• mdBdReceiveEx function
• mdBdRandWEx function
• mdBdRandREx function
• mdBdWriteLinkDeviceEx function
• mdBdReadLinkDeviceEx function
• CCPU_ClearError function
Setting range Default
20 to 2000 [ms] 1000 ms
(10 ms units)