# Frozen Alarm Ignition

**URL:** <https://forum.inductiveautomation.com/t/frozen-alarm-ignition/110107>\
**Category:** Ignition\
**Created:** [August 22, 2025, 1:19pm UTC](https://forum.inductiveautomation.com/t/frozen-alarm-ignition/110107 "2025-08-22T13:19:19Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![kennethandrad](https://avatars.discourse-cdn.com/v4/letter/k/ce7236/32.png) [@kennethandrad](https://forum.inductiveautomation.com/u/kennethandrad)\
**Post date:** [August 22, 2025, 1:19pm UTC](https://forum.inductiveautomation.com/t/frozen-alarm-ignition/110107/1 "2025-08-22T13:19:19Z")

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Hi, I need to create an alarm for a tag with a particular issue: sometimes the tag value gets "frozen." For example, it stays at 15, 15, 15, 15… continuously until the PLC is reset. And it’s not always 15; it could be any value, like 0, 0, 0, 0… or 30, 30, 30, 30… So when the PLC disconnects, the tag gets stuck at a specific value. Is there a type of alarm that can identify when a value is frozen? Because from what I see, alarms are usually based only on setpoints. How could I create an alarm of this kind?

I would like that if the tag remains frozen at any value for 30 seconds, it should then trigger an alarm

Thanks very much.

 ![image](https://us1.discourse-cdn.com/inductiveautomation/original/3X/a/f/af69b766f2727d0f99982445b90b0d7d4821efab.png)

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**Author:** ![pturmel](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/pturmel/32/3295_2.png) [@pturmel](https://forum.inductiveautomation.com/u/pturmel)\
**Post date:** [August 22, 2025, 2:00pm UTC](https://forum.inductiveautomation.com/t/frozen-alarm-ignition/110107/2 "2025-08-22T14:00:57Z")

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There's no built-in way to do this. The simplest way others have handled this is to use two additional tags:

- a datetime memory tag to which `system.date.now()` is written as a timestamp whenever the subject tag changes (using a tag `valueChange` event script, excluding initial changes).
- a boolean expression tag that regularly compares `now()` against the timestamp memory tag plus the desired idle limit, turning true when unchanged too long.

The alarm would then be defined on the expression tag.

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**Author:** ![Chris\_Bingham](https://avatars.discourse-cdn.com/v4/letter/c/e5b9ba/32.png) [@Chris\_Bingham](https://forum.inductiveautomation.com/u/Chris_Bingham)\
**Post date:** [August 25, 2025, 5:09am UTC](https://forum.inductiveautomation.com/t/frozen-alarm-ignition/110107/3 "2025-08-25T05:09:16Z")

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Another option:

A single memory tag, same tag group as monitored tag, boolean, with the following expression (where PLC\_Heartbeat is intended to be a changing/incrementing tag in the same folder - tweak to suit):

`hasChanged({[.]PLC_Heartbeat}, false)`

Then, add an alarm on that boolean tag when condition = False, + a delay.