My experience with the network watchdog and the cFP21xx series is you have to reset unit after an event. When it says "Halt system", it means just that. I have not found a setting to get around this.
This does not directly apply to you but I found this in a cFP manual. It may hint at a somewhat limited range of function for the network watchdog.
NoteNational Instruments recommends leaving the network watchdog disabled when
you are running embedded applications on the cFP-21xx. Refer to the section of this
chapter for information about the hardware watchdog for embedded applications.
My problem is that the Hardware Watchdog functions don't show up on my Real Time palette like they used to. Not sure where they are now.
Hopefully it's not you crawling up that stack!
Here's a pie in the sky idea. You might consider some sort of watchdog external to the cFP module. Let's say you modify your setup to toggle a DO output every once in while and monitor that with some sort of hardware watchdog that disables the heaters if it doesn't see the activity. Not sure if anyone currently makes such a hardware watchdog that is self contained.
Hmm, I like that idea.
If I had some kind of rising-edge trigger, with a timeout, then a stuck-on digital output wouldn't burn up the system. The signal would then be sent periodically, telling the unit to "remain on," and the fail-safe would be in the hardware. I might run that past them.
There are off the shelf units that do that, you can set the time with knobs and there are digital units too. If interested, I can pass a few links your way. Omron, P&B, Crouzet are a few mfg's.
Off-delay and single shot timer are common terms, see explanation here in this data sheet:
Some examples of units in various flavors, don’t know your contact rating requirements, but there are gobs of choices out there. I didn’t look specifically for one with a DC trigger input:
Hope this is the direction you need
I think the AnalogKid is on to something. Here is a link to a Magnecraft part that has a 'Retriggerable One-Shot' mode that would be perfect as a watchdog.