Multiple RFID readers access control system

Blazing fast replies! I love that.

I see...I took a look at the link you gave me. However, it says that it only read? So I cannot write any information into the card? Also if you happen to have card that can be written into, what is the size of the storage.

The project started as an access point but eventually the system shall grow into a management system which required the card to hold information of the students such as serial number, course number etc and a purse value. Just like the MiFARE or FeliCa contactless smart cards.

Do you happen to have readers and media that capable of doing that? I had experience in creating MIFARE single access point system tho, if that helps.

If you need help with the MiFARE and FeliCa, just lemme know. I can explain it to you in general tho. But..man...you have awesome system architecture ..I only wish that the reader could read Mifare and FeliCa...

Yeah, the RedBee reader only supports the EM41xx family of tags in the 125KHz range. Tags like the MiFare and FeliCa are typically HF 13.56MHz tags and require a different air interface. Also I think the RedBee communication protocol would have to be changed a bit to support read/write support and deal with anti-collision features which create the possibility of multiple tags in the field at once. Anyway, let's let the dust settle on the RedBee first eh? :)


Edited by amal - 16 March 2010 at 8:53pm

Aight amal, I am trying to negotiate and discuss with the college admin regarding this. I ll update ya .

songbreaker wrote: I have explained that it is still possible to use the EM41xx technology instead of the smartcards (MIFARE, FeliCa) but I would just need a constant online connection for access/transaction that uses money and other information as everything would have to be done on server side. This can be done, it is not impossible in my calculation and design.

I would caution that while it can be done, any system that transacts money or monetary value using EM41xx tags runs the risk of someone emulating another user's tag ID. The EM41xx cards are just not secure. Skimming EM41xx tags takes no effort at all, and the circuitry required to emulate those tags is already out there and available in more than one variety. Where there is direct financial gain involved, don't think someone won't go through the trouble.

songbreaker wrote: However they want that the issued tags can be controlled; in other words, can we decide the tags serial numbers? I know that the tags is not writable, but somehow, is there any initializing machine/device for the tags?

Usually this requirement stems from an attachment to other types of technology, like hotel room keycards where the magnetic strip can be easily written over. With read only tags like the EM4102, the tag ID cannot be changed so the database handles the proper association of tag ID to data. In the hotel room keycard scenario, instead of writing over the magstripe on the keycard the database simply reconfigured the "authorized card" list for a particular room to only accept the cards the desk clerk scans before handing them to the customers. Of course, the advantage of rewritable keys is that you can ensure the door lock and the key card IDs used are both changed to something random, and there would be almost no way a past customer could scan their card ID and run down the hallways with an emulator looking for a new room that has their old card ID assigned.

songbreaker wrote: Secondly, they are amazed by the 255 per node capability of the RedBee technology, however, supposed that there are certain places that require wired networking, how am I supposed to design the system? I am thinking of using multiple I/O card in a terminal and connect the readers with RS-232 for short distance and RS-485. Is there any other smarter way? The best multiple I/O card that I ever came across with is MOXA

The RedBee reader has a USB port on it, which acts as a virtual com port when connected to a PC. I believe Windows can support up to 255 virtual com ports as well. Assuming you can write some software that can communicate with readers through multiple serial ports, you should be able to "talk" to a very large number of readers... even more than 255 if you split them into wireless "zones". You already know how wireless XBee communication works, but you can also talk directly to readers via USB virtual com ports. If the readers are spread out over long distances, you can use devices like USB network servers to connect to the RedBee readers over Ethernet networks (or even the Internet). A setup that uses both forms of communication could look something like this;




Edited by amal - 21 March 2010 at 12:34pm