The Flex600ST features a watchdog timer that can generate a system reset if the CPU processing comes to a halt. This feature ensures the system dependability during unattended operation. The watchdog timer is programmable. In order to program the watchdog timer, a program writing I/O port address 444(hex) needs to be written first. The output data is a value of time interval. The value ranges from 01(hex)to 3F(hex), and the related time interval ranges from 0 to 63 seconds.

After entering the data, the program has to refresh the watchdog timer by rewriting the I/O port 444(hex) and setting it at the same time. To disable the watchdog timer, the program should read I/O port 441(hex).

Download the way to program the watchdog timer in BASIC