Defining A Watchdog Timer - Allen-Bradley PLC-5 User Manual

Defining a Watchdog Timer

To define a controller fault routine:
For more information about fault codes, see the documentation for your
programming software.
The watchdog timer (S:28) monitors the program scan. If the scan takes
longer than the watchdog timer value, a fault routine is initiated and executed.
The timer is the maximum time (in ms) for the watchdog; or if you use an SFC,
it is the maximum time for a single pass through all the active steps.
To define a different value other than the default: .
The watchdog timer can go only as low as 10 ms,
IMPORTANT
even though the programming software allows
single-digit inputs
Preparing Fault Routines
Publication 1785-UM012D-EN-P - July 2005
15-5