Eaton HFX Series Installation And Operation Manual

EATON HFX Product Family Installation and Operation Manual E-ELCL-II002-E2 July 20191812.4 Watchdog OperationWatchdogs are present to provide an indicationthat something has gone wrong. Systems that areprogrammable can hang for a number of differentreasons. One of the most common is the executionof an infinite loop due to a programming logic error.This type of failure prevents any of the other codefrom executing. Also, if an unusual number ofinterrupts arrives during a single cycle of the loop thiscan prevent the main loop from having sufficient timeto execute. Another possibility is a failure in hardwarethat causes a constant reset.Each controller has an internal hardware watchdogthat is continuously running in the background tomonitor for a system malfunction. This watchdogis not user serviceable and is not visible to the user.It will trigger in the event of a task timeout and canonly be reset through a hard reset of the controller,which means that the user must connect the servicetool or IEC programming tool to the controller,tie PWM 1 & 2 to supply voltage, and then powerup the unit. This will prevent the IEC applicationcode from loading.Each controller also features asecond watchdog, which monitors the Pro-FX Controlruntime system with a default value of 2 secondsand recommendation to be set above a minimum100 ms. This is user configurable via the SystemConfig Configuration 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 specific tasks; the time is user configurable via the TaskConfiguration/MainTask tab (see below screen). For additional details see Pro-FX Control online help. It is typicallyreset by resetting an associated fault.HFX Product Family