Hardware Information
7-7
SIMATIC Rack PC 840 Manual
A5E00104826-03
7.4.4
Watchdog (WD)
Function
The watchdog monitors the execution of a program. The purpose of the WD is to
notify the user of a program crash through 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 will be triggered and the Watchdog LED is
switched off. If the watchdog is activated (by driver or SOM program) the
Watchdog LED is green.
WD Reactions
If the WD is not triggered again within the set time (by driver or SOM program), the
following reactions are initiated:
Reaction
Option
Watchdog LED switches from green to red
–
Initiate reset of the PC
adjustable
SOM application is displayed
–
The reactions which are to be triggered can be parameterized by driver or
SOM program.
WD Monitoring Times TWD
The monitoring times 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 activated (i.e., while the
watchdog is running), the watchdog is retriggered!
Summary of Contents for SIMATIC Box PC 840
Page 8: ...Preface viii SIMATIC Rack PC 840 Manual A5E00104826 03 ...
Page 179: ...B 1 SIMATIC Rack PC 840 Manual A5E00104826 03 Technical Specifications B ...
Page 208: ...Glossary Glossary 22 SIMATIC Rack PC 840 Manual A5E00104826 03 ...
Page 212: ...Index Index 4 SIMATIC Rack PC 840 Manual A5E00104826 03 ...