RFID readers

    Aug 17 2008 | 4:28 pm
    Hello all.
    I would like to use an RFID reader for a project and am looking for advice as to where I can find a suitable device.
    What I need is the possibillity of knowing when a tag enters the field of the reader, even if other tags are in the field at the time. I belive that for instance the core-20 rfid reader does not permit several tags to be in the field at the same time and will not report a new tag as long as the old one remains in the field.
    If anyone has a suggestion for a suitable reader that may also interface with max in a reasonable manner that would be great.
    I would like to stay in the passive lf area as I need the tags to be as thin as possible.
    Thank you.

    • Aug 17 2008 | 9:52 pm
      I have used the Parallax (http://www.parallax.com/Store/Microcontrollers/BASICStampModules/tabid/134/txtSearch/rfid/List/1/ProductID/114/Default.aspx?SortField=ProductName%2cProductName) that you can find quite easily in Europe (at least in the UK, France, Netherland where I check).
      You have to connect it to a Basic Stamp or an Arduino which can then send the information to Max.
      The phidget has an USB port for direct connexion with your computer but I haven't used it yet (http://www.phidgets.com/products.php?category=8).
    • Aug 17 2008 | 10:28 pm
      Thank you for your suggestions.
      Yes I have seen these modules. However it states in the documentation for both of them that it is only possible to hold one tag up to the reader at any time and that multiple tags will "confuse" the reader. What I need is a reader that can accept several tags being in the field at the same time, and at least any new arrival being registered as it enters the field.
      So if anyone knows of a reader that can accept having multiple tags in its field please let me know.
      Thank you.
    • Aug 17 2008 | 11:40 pm
      Very few RFID readers can read multiple tags. Most of them just give an error, if anything. The anticollision is difficult ot implement. The way I've seen it done is to subdivide the band into 16 chunks and have the tags respond within their sub-band. You can't overlap the tags, however. There are some other restrictions, too.
      The only one that I have worked with that can read multiple tags is made by Texas Instruments. I warn you, it is not a simple reader. The protocol is a pain-in-the-ass and the tags are not re-writable. The eval kit is not cheap, either: $600.
      The part number for the tags is RI-I03-112A-03. They are paper thin. (And they are very cheap.)
      The part number for the eval kit is RX-MFR-RNLK-00.
      I recommend calling TIRIS, Texas Instruments' RFID division, and talking to an application engineer.