Advantech PCA-6151, Manual, Page: 42 / 46

34 PCA-6151 User's Manual
Programming the Watchdog Timer
If you decide to program the watchdog timer, you must write a
program which reads I/O port address 443 (hex). The output data
is a value timer. You can write from 01 (hex) to 3E (hex), and the
related timer is 1 sec. to 63 sec.
After data entry, your program must refresh the watchdog timer by
rewriting the I/O port 443 (hex) while simultaneously setting it.
When you want to disable the watchdog timer, your program
should read I/O port 043 (hex).
The following is an example of a program for the watchdog timer:
Step 1 Out 443h data REM Start and reset the watchdog timer
Step 2 Your application task #1
Step 3 Out 443h, data REM Reset the timer
Step 4 Your application task #2
Step 5 Out 443h, data REM Reset the timer
Step 6 in 043h, REM Disable the watchdog timer
Data Values
01
1 sec.
02 2 sec.
03 3 sec.
04 4 sec.
.
.
.
3E 63 sec.