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7. AUXILIARY FUNCTION
7.7 User watchdog function
User watchdog function is a function that checks for errors of the user program. Reset the value of watchdog
check counter on the dual port memory using a host controller on a periodic basis. If the watchdog check
counter value is not reset at the designated time (watchdog timer counts down to zero), it is determined that
the host controller error and a forced stop status is entered.
The position board decrements the watchdog timer on each control cycle until the watchdog check counter
value is reset. When the watchdog check counter value is reset, it is reset to the value set for the watchdog
timer start counter.
POINT
When the watchdog timer start counter is set to 0, user watchdog is not
executed.
API LIBRARY
Use the sscWdEnable/sscWdDisable functions to enable/disable user
watchdog function.
Use the sscChangeWdCounter function to update the watchdog check
counter.
For a detailed procedure for watchdog, refer to the sample program
(WatchDog) contained on the utility software.
(1) Normal conditions
n n+1 n+2 n+3
432543543 543
W
atchdog time
r
W
atchdog chec
k
counte
r
sscChangeWdCounter
function
sscChangeWdCounter
function
sscChangeWdCounter
function
sscChangeWdCounte
r
function
(2) When host controller overruns
nn+1
432543210Watchdog timer
Watchdog check
counter
Host controller determined
to be in overrun and a forced stop
status is set.