Remote Processing RPC-330 - Manual (Page 40)

WATCHDOG TIMER SECTION 11
Page 11-1 RPC-330
DESCRIPTION
The watchdog timer is used to reset the RPC -330 if the
program or CPU "crashes" . The time r is built into the
80C320 CP U. Timed access requirem ents built into the
CPU make it high ly unlikely an er rant pr ocessor would
cancel a watchdog timer.
The watchdog should not be used in loops which do not
end quickly or ar e of indetermina te duration unless a
WDOG command is included. An example of an
indeterminate loop is one that waits for a port condition
to change.
The timer is set by executing a WDOG n command. n is
0, 1, or 2. 0 turns off the timer. 1 sets the watch dog
time to 380 ms while 2 sets it to 2.8 seconds. Executing
WDO G by itself resets the timer. WD OG must be
executed pe riodically to p revent a reset.
EXTERNAL RESET
The card is reset externally by mom entarily shorting
W10[1- 2]. R eset is also achiev ed by shor ting W10-2 to
ground. Maintain this short for at least 10 ms. The card
will then reset for abo ut 350 ms.