Siemens PANEL PC 877 operating instructions Watchdog WD, WD reactions, WD monitor times TWD

Functions

11.4 Watchdog (WD)

11.4Watchdog (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!

SIMATIC Panel PC 877	11-5
Operating instructions, Release 07/2006, A5E00877780-01