View Full Version : Parallax RFID reader: For Cat-tracker project, compatibility, practical hints/t

08-14-2005, 08:22 PM
Hi everybody,

This is only my second post here on this forum, i'm a bit of a newbie here in BS2 land. But i think i'll stick around for a while because i think that the BS2 can do the job for the one or two projects that i have in mind. I have a fair amount of experience with electronics and mechanics, i've built my own CNC machine, among other things.

Off and on i have been working on a Cat-tracker project. It started all a few years ago, way before i started to get interested in Microcontrollers like the BS2 and PIC. I started off with 6 cats. One got hit by a car and had to be put down because of massive injuries. One is missing in action (although he had been tagged) and one is given away to my sister. I am left with three cats now, all of them have been tagged by the vet. For the record: The cats were tagged for practical reasons only, way before the existance of plans about this project. The cats were NOT tagged just for the purpose of this project.

In the Netherlands, it is custom to tag (and officially register) stray cats when brought to the vet. Pet owners are free to choose to tag or not. The tag (2mm by 13mm) is inserted under the skin by the vet with a hyperdermic needle (2,5mm by 30mm) and the procedure is·NOT known to be extremely painfull. In fact, the cats were more in shock for being there, rather than having another shot in their neck. The whole procedure takes only 5 to 10 seconds. All in all no big deal. The tag is placed between the shoulder blades, or sometimes a bit near the left shoulder blade. The tag is an ISO type·(FDX-B) transponder operating on 125KHz. The identification is 15·digits long. For the Netherlands, the ID starts with 528, followed by another 12 numbers.

For more information, you could visit http://www.virbac.com (I have no relationship with this firm / website whatsoever)

I want to place an RFID reader above the cat door at the back of my house. Only your own imagination is the limit with this. My own cats can open the small door, followed by·a sound that is related to that particular cat.·Neighbouring cats cannot open the door and are welcomed by the sound of a barking dog·http://forums.parallax.com/images/smilies/lol.gif, for instance. All this connected to my (web)server with MySQL and·1-wire Weatherstation and i can draw my own conclusions whether how much the cats are out, how long they are out en under wich circumstances they leave or enter·the house. Bla·bla bla, etcetera etcetera... You get the idea.

My questions:
1) The most important one: The RFID reader from Parallax, does it operate·with the ISO FDX-B standard? Is it proven to be operating with the mentioned ISO tags on 125KHz?
2) In the past i experienced difficulties with the reading distance. I had to press the reader on the back of the cat to get a reading. Is this reader sensitive enough to read from a small distance through the skin of the cats?
3) The tag is on the left side of the cat. So when they turn around, they may be facing away from the reader. Can i place two of these readers on left and right side of the Cat tunnel? What about interference? Maybe connecting RFID antennas in parallel, disabling the second circuit?

I could mount a round Parallax tag on the cats collars, but the collars rotate all the time. They could face away from the readers, preventing them from entering the house. Besides, the cats allready have their tag. It would be disappointing to have to use other tags instead. My first RFID reader was quite expensive, around 150 Euro's and it lacked reading distance. Sure, i could buy two of those Parallax readers, and just try it out. In comparison they cost allmost nothing·(And i shure dont want any angry Germans on my back insulting me for being cheap http://forums.parallax.com/images/smilies/lol.gif). But if i can find out that these readers do not work with ISO tags, than it saves me some money that i can spend on Basic Stamps instead!·http://forums.parallax.com/images/smilies/eyes.gif

I am convinced, that IF these readers work fine with ISO tags, that the BS2 can make it work for me.

Thanks for any help on this subject, keep up the good work Parallax!


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

Post Edited (Mr.Ed) : 8/14/2005 1:39:59 PM GMT

08-14-2005, 09:29 PM
This is from the RFID documentation:

The Parallax RFID Reader Module works exclusively with the EM Microelectronics-Marin SA EM4100-familyof passive read-only transponder tags. A variety of different tag types and styles exist with the mostpopular made available from Parallax. Each transponder tag contains a unique identifier (one of 240, or1,099,511,627,776, possible combinations) that is read by the RFID Reader Module and transmitted tothe host via a simple serial interface.

Dave Andreae

Tech Support
dandreae@parallax.com (mailto:dandreae@parallax.com)


08-14-2005, 10:19 PM
Thank you·Dave, for the quick reply,

Reading this is a very big disappointment for me. I visited the EM website and the ISO tag readers were indeed mentioned furtheron down the list. I must conclude then, that for me the Parallax RFID reader is definately not going to work at all. The ones i need support the ISO 11784 and ISO 11785 standard, like for instance the EM4469/EM4569.

I could still go ahead with the project, using my allready bought reader. It has no further influence of using the BS2. But as mentioned before, my current RFID reader has very limited reach and will definately produce reading difficulties.

I think i'll pay the manufacturer of my reader another visit. Maybe, he has a possible solution with a larger antenna. For those who are interested: http://www.datatronic-rfid.com (look for Compact Reader with Micro Engine).

I welcome further information about programming the BS2 in relation to RFID and all that comes with it!



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

Post Edited (Mr.Ed) : 8/14/2005 3:55:09 PM GMT