I have made extensive use of timestamp profiles to define items which represent the last update(or change) time of another item that is bound to a channel. However, I have a use case related to smoke detectors where I have defined a switch item which I use to track whether the smoke detector has reported a heart beat in the last hour. The value of this tracking item is set in rules. I would like to define a last update item that derives its value not based on a channel, but based on when another item last changed value (or updated value). Is that possible using profiles, or do I need to just do this using rules?
Profiles only work on the link between a Channel and an Item.