Eaton HFX Series - Watchdog Operation

EATON HFX Product Family Installation and Operation Manual E-ELCL-II002-E2 July 201918
12.4 Watchdog Operation
Watchdogs are present to provide an indication
that something has gone wrong. Systems that are
programmable can hang for a number of different
reasons. One of the most common is the execution
of an innite loop due to a programming logic error.
This type of failure prevents any of the other code
from executing. Also, if an unusual number of
interrupts arrives during a single cycle of the loop this
can prevent the main loop from having sufcient time
to execute. Another possibility is a failure in hardware
that causes a constant reset.
Each controller has an internal hardware watchdog
that is continuously running in the background to
monitor for a system malfunction. This watchdog
is not user serviceable and is not visible to the user.
It will trigger in the event of a task timeout and can
only be reset through a hard reset of the controller,
which means that the user must connect the service
tool or IEC programming tool to the controller,
tie PWM 1 & 2 to supply voltage, and then power
up the unit. This will prevent the IEC application
code from loading.Each controller also features a
second watchdog, which monitors the Pro-FX Control
runtime system with a default value of 2 seconds
and recommendation to be set above a minimum
100 ms. This is user congurable via the System
Cong Conguration tab (see below screen).
Note: That this watchdog is reset using the same protocol used to reset the internal hardware watchdog.
Pro-FX Control also has a watchdog that monitors specic tasks; the time is user congurable via the Task
Conguration/MainTask tab (see below screen). For additional details see Pro-FX Control online help. It is typically
reset by resetting an associated fault.
HFX Product Family