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RFID Reader Frequency ? — Parallax Forums

RFID Reader Frequency ?

Del TapparoDel Tapparo Posts: 7
edited 2005-12-12 15:57 in General Discussion
I am considering using the Parallax RFID Reader. www.parallax.com/detail.asp?product_id=28140
According to the .pdf document, this unit operates at 170 KHZ. Is this correct? From my limited research, it seems that most low frequency readers operate at 125 Khz.

Comments

  • John R.John R. Posts: 1,376
    edited 2005-12-12 00:25
    Welcome to the club of confusion on this. Depending on what information you read, there are a number of apparently conflicting numbers thrown out on this.

    The most significant is that the reader is compatible with any of the various EM-410x tags. These are nominally "125 kHz", but vary from 100 to at least 150, and Paralax is not the only refernece I've seen at 170 kHz. I have used tags that are both EM4100 and EM4102. I am also under the impression that EM4105 will also work.

    I am not going to claim to be an "expert" in RFID, I've just recently been (and am still going further down) this road.

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    John R.

    8 + 8 = 10
  • Del TapparoDel Tapparo Posts: 7
    edited 2005-12-12 00:48
    John R. said...
    Welcome to the club of confusion on this. Depending on what information you read, there are a number of apparently conflicting numbers thrown out on this.

    The most significant is that the reader is compatible with any of the various EM-410x tags. These are nominally "125 kHz", but vary from 100 to at least 150, and Paralax is not the only refernece I've seen at 170 kHz. I have used tags that are both EM4100 and EM4102. I am also under the impression that EM4105 will also work.

    I am not going to claim to be an "expert" in RFID, I've just recently been (and am still going further down) this road.

    Well that is encouraging at least. I would like to use a 30mm round tag, or smaller. I don't know what EM-410x tages are (but I will be Googling soon). Most of the tags I looked at specs on, were 125 KHZ +- 10%. That would certainly not include 170 KHZ.

    Thanks for your help John. smile.gif
  • John R.John R. Posts: 1,376
    edited 2005-12-12 01:05
    The 125kHz tags will probably work. The EM410x is pretty much "standard" for all the low cost tags I've seen. Basically, this is a pasive tag (no onboard power) in the nominal 125kHz range.

    In the docs for the reader, it also references the 125kHz frequency. I've got stuff (including notes) packed away, but I remember reading more in the range of 140kHz with a frequency reading on my hand held DMM.

    I've used tags from Parallax, Phidigits and an OEM (purchased from a "third party") with success.

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    John R.

    8 + 8 = 10
  • Del TapparoDel Tapparo Posts: 7
    edited 2005-12-12 01:25
    I just found the mfg's spec sheet on the tag that Parallax sells. It says 125 KHZ +- 6 KHZ. So, I have to assume that if I buy a 30 mm tag from someone else, it will also work.
    www.sokymat-usa.com/DataSheets/WORLD%20TAG%20Unique%20-%2050%20mm%20-%20V4.pdf
  • Guenther DaubachGuenther Daubach Posts: 1,321
    edited 2005-12-12 08:34
    The Parallax RFID reader makes use of an EM4095 chip. According to the datasheet, this device operates at 125 kHz. I have five of these readers here, and they work very well. I'm using the round tags sold by Parallax but any other 125 kHz tag should also be ok.

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    Greetings from Germany,

    G
  • Mr.EdMr.Ed Posts: 35
    edited 2005-12-12 14:46
    Guenther Daubach said...

    ...but any other 125 kHz tag should also be ok.

    Well Guenther, ... Let's be carefull here...You are partly correct, but there is a bit more to it than that...

    In general, there are the HDX (Half Duplex) readers / transponders wich work on a single frequency, for instance on 125KHz, and there are the FDX-B (Full Duplex) readers / transponders wich work on two frequencies, for instance 125KHz AND 134KHz. More frequencies are possible, but let's not add more confusion to this subject. AFAIK, HDX and FDX-B are not compatible. So,··for instance,·a pets tag (FDX-B) can not be read with a HDX reader (the Parallax kind). So, back to the quote, "... any other HDX 125KHz tag should also be ok."

    ·I asume you allready knew this, but others might not be aware of this. They could purchase readers or tags (HDX with FDX-B mixed) and get disappointed by the results.
    John R. said...

    I am not going to claim to be an "expert" in RFID, I've just recently been (and am still going further down) this road.
    That goes for me too smilewinkgrin.gif

    Best regards,

    Ed.



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    A horse is a horse, of course of course...

    Post Edited (Mr.Ed) : 12/12/2005 2:56:11 PM GMT
  • Guenther DaubachGuenther Daubach Posts: 1,321
    edited 2005-12-12 15:57
    Hi Mr. Ed (a hourse is a hourse, of course of course...),

    thanks for clearing this up - you are absolutely right, the Parallax RFID reader can only deal with HDX transponders on a single 125kHz frequency.

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    Greetings from Germany,

    G
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