Siemens SIMATIC 627B, Operating Instructions Manual

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Functions
9.3 Watchdog (WD)
SIMATIC Box PC 627B
60
Operating Instructions, 06/2008, A5E00927393-02
9.3 Watchdog (WD)
Function
The watchdog monitors program execution and reports a program crash to the user by
means of various reactions.
The watchdog is idle when the PC is switched on or after a HW-RESET(cold restart), i.e., no
reaction of the WD is triggered.
WD reactions
If the WD is not retriggered within the set time (by the driver or in the SOM program), the
following reactions are triggered:
Response Option
WD acknowledgement None
Trigger a PC reset Selectable
SOM or DiagMonitor software is activated None
WD monitoring times (TWD)
The monitoring times can be set in increments of one second within a range from 3 to 255
seconds.
Note
The watchdog is retriggered if the monitoring time is changed at the active watchdog (that is
while the watchdog is running)!
9.4 Fan monitoring
The function monitors operation of the enclosure and power supply fans. When a fan fails,
the following reactions are triggered:
Response Option
SOM or DiagMonitor software is activated None
The temperature error is retained until the cause of the fan failure has been rectified and the
error is reset in one of the following ways:
●
Acknowledgement of the error message by means of the SOM program
● Restart of the device