New Transducers TR-5001 - Manual (Page 50)

Watchdog Timer Configuration
The function of the watchdog timer is to reset the system automatically
and is defined at I/O port 0843H. To enable the watchdog timer and
allow the system to reset, read I/O port 0443H. To disable the timer, read
I/O port 043H for the system to stop the watchdog function. The timer
has a tolerance of 20% for its intervals.
The following describes how the timer should be programmed.
Enabling Watchdog
MOV DX, 0843H
IN DX, AX
Disabling Watchdog
MOV DX, 043H
OUT DX, AX
46 TR-5001 User Manual