Watchdog (Wd) - Siemens SIMATIC PANEL PC 877 Operating Instructions Manual

11.4

Watchdog (WD)

11.4
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
WD acknowledgement
Trigger a PC reset
SOM or DiagMonitor software is activated
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!
SIMATIC Panel PC 877
Operating instructions, Release 07/2006, A5E00877780-01
Option
None
Configurable
None
Functions
11.4 Watchdog (WD)
11-5