Advantech PCA-6148 User Manual page 84

Programming the watchdog timer
If you decide to program the watchdog timer, you must write data
to I/O port 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 procedure is a program for the watchdog timer:
Step 1
Step 2
Step 3
Step 4
Step 5
Step 6
Data Values
01 1 sec.
02 2 sec.
03 3 sec.
04 4 sec.
.
.
.
3F 63 sec.
76 PCA-6148/6148L User's Manual
Out 443h data REM Start and reset the watchdog
timer.
Your application program task #1
Out 443h data REM Reset the timer
Your application program task #2
Out 443h data REM Reset the timer
in 043h, REM Disable the watchdog timer