Advantech TPC-1261H - Manual (Page 59)

49 Chapter B
B.2 Watchdog Timer Programming
The I/O port address of the watchdog timer is 2E(hex) and 2F(hex), 2E
(hex) is the address port. 2F(hex) is the data port. You must first assign
the address of register by writing address value into address port 2E(hex),
then write/read data to/from the assigned register through data port 2F
(hex).
Figure B.1: Watchdog timer programming procedure