Siemens SIMATIC PANEL PC 877 - Manual (Page 113)

Functions
11.4 Watchdog (WD)
SIMATIC Panel PC 877
Operating instructions, Release 07/2006, A5E00877780-01
11-5
11.4
11.4
Watchdog (WD)
Function
The watchdog monitors the 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 triggered again within the set time (by driver or SOM program), the following
reactions are initiated:
Response Option
WD acknowledgement None
Trigger a PC reset Configurable
SOM or DiagMonitor software is activated None
WD monitor times (TWD)
The TWD are adjustable in increments of one second in a range from 3 to 255 seconds.
Note
If the watchdog time is changed after the watchdog was enabled (i.e., while the watchdog is
running), the watchdog is retriggered!