Advantech PCI-6870 Series, User Manual

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PCI-6870 User’s Manual 98
Appendix A Programming the Watchdog
Timer
A.1 Programming the Watchdog Timer
In order to program the watchdog timer, you must write a program which
writes I/O port address 443 (hex). The output data is a value of time inter-
val. The value range is from 01 (hex) to 3E (hex), and the related time
interval is 1 sec. to 62 sec.
Data Time Interval
01 1 sec.
02 2 sec.
03 3 sec.
04 4 sec.
. .
. .
. .
3E 62 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 443 (hex).
The following example shows how you might program the watchdog
timer in BASIC:
10 REM Watchdog timer example program
20 OUT &H443, data REM Start and restart the
watchdog
30 GOSUB 1000 REM Your application task #1
40 OUT &H443, data REM Reset the timer
50 GOSUB 2000 REM Your application task #2
60 OUT &H443, data REM Reset the timer
70 X=INP (&H443) REM Disable the watchdog timer
80 END
1000 REM Subroutine #1, your application task
.
.
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