Advantech MIC-3369C, User Manual

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MIC-3369 User’s Manual 68
Appendix A Programming the Watchdog
Timer
A.1 Programming the Watchdog Timer
To program the watchdog timer, you must write a program which writes a
value to I/O port address 443 (hex). The output value represents a time
interval. The value range is from 01 (hex) to FF (hex), and the related
time intervals are 1 sec. to 255 sec.
Data Time Interval
01 = 1 sec.
02 = 2 sec.
03 = 3 sec.
04 = 4 sec.
FF = 255 sec.
After data entry, your program must refresh the watchdog timer by rewrit-
ing to the I/O port 443. When you want to disable the watchdog timer,
your program should read I/O port 043 (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 (&H043) REM, Disable the watchdog timer
80 END
1000 REM
Subroutine #1, your application task
1070 RETURN
2000 REM
Subroutine #2, your application task
2090 RETURN.