I'm guessing that probably what you mean by "Alarm Signal" is a "Fire Alarm" that gets everybody out of the building, shuts doors, shuts down the air handlers, stops industrial processes, etc. The answer, though, to what happens when an input or output device goes into trouble is a little less clear.
It Depends
I've dealt with nursing homes, hospitals, and schools that when the fire alarm system has any trouble, like a missing smoke detector or even a bad battery, the doors have to unlock. That would be a "Trouble Alarm". The trouble alarm, though, in those cases, wouldn't sound the "Fire Alarm".
Whether doors unlock or processes stop with any fire alarm system depends entirely on how the system is programmed, and how the system is wired. If the system is programmed and wired to shut down industrial processes when a trouble signal occurs, then the process will shut down when a trouble signal occurs.
I know that you're looking for a specific answer to what happens with your system when there's a trouble. However, because the answer depends so much on the programming and wiring for the whole fire alarm system, and also for the process controls, I can't give a better answer.
Douglas Krantz
