Advantech PCI-6872 Appendix A Programming the Watchdog Timer, A.1 Supported Input Timing Modes

Appendix A Programming the Watchdog Timer

A.1 Supported Input Timing Modes

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.

044 sec.

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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:

10REM Watchdog timer example program

20OUT &H443, data REM Start and restart the watchdog

30GOSUB 1000 REM Your application task #1

40OUT &H443, data REM Reset the timer

50GOSUB 2000 REM Your application task #2

60OUT &H443, data REM Reset the timer

70X=INP (&H443) REM Disable the watchdog timer

80END

1000 REM Subroutine #1, your application task

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PCI-6872 User’s Manual 88