Operators Manual User guide

04/12 59 51146 Rev. 3
Appendix V: Programming the Watchdog Timer
The FB3000 Embedded PCB provides a Watchdog Timer that resets the CPU or
generates an interrupt if processing comes to a stop.
─ This function ensures greater system reliability in industrial standalone and
unmanned environments.
─ T o enable the Watchdog Timer, output the value of the Watchdog Timer
Interval to the Controller.
─ The value range is from 01H to FFH , and the related time Watchdog
Timer interval is one (1) second to 255 seconds .
NOTE: To program the Watchdog Timer, write the timer value to the I/O Port
444 (hex).
Example: Assembly Language
DATA TIMER INTERVAL
00 Disabled
01 One (1) second
02 Two (2) seconds
* *
* *
FF 255 seconds
Start Watchdog Timer DOS Debug
MOV DX, 444H OUT 444, XX
MOV AL, XXH
OUT DX, AL
Start Watchdog Timer DOS Debug
MOV DX, 444H IN 441
IN AL, DX