Is such software available? If so, how would it work?
This is what all RFID software does. Each time a tag is interrogated, the reader sends the tag ID number, as well as the reader ID, sometimes an antenna ID, and the date and time at which the tag was read, to middleware or directly to a back-end database. Since the reader ID is associated with a location (at least if the deployment was properly carried out), that location is noted in the database.
Let's say, for example, that a container of parts comes into a warehouse through dock door number 8. The identifier of the reader at that dock door is associated with door number 8, so when the container tag is interrogated, the information on what is received and where it was received is updated in the database. This is fundamental to all RFID software.
In the case of active real-time location systems, the tag sends out a signal at regular intervals and several readers pick it up. Software calculates the item's location on a facility map. Most systems don't update the location with every ping. Instead, they update the asset's location based on pre-defined rules. If the asset were moved to a specific room, that event would likely be recorded in a database—but if it were moved a few feet down the hall, it would not be. At any given time, you could call up a map and find that asset's location at the time that it last broadcast its signal.
—Mark Roberti, Founder and Editor, RFID Journal