Proximity readers


I am looking to build a building security system using either proximity tags or swipe cards, connnected to a single-board-computer control system that will present access logs, and accept authorisation commands from authorised users via a web browser.

The software side of things, I can deal with. I plan to run the entire thing on a network of 486-based wafer cards running Linux, provided that this is possible.

What I don't know about is how to interface card readers / prox.tag readers to these boards. Do these devices usually present some kind of RS-232 interface, or is it some weird custom thing that I am going to have major difficulties with?

Presumably, the interface presented varies from type to type, so Ideally, I'd like to find a basic reader that I can talk to / be-talked-to down a serial line.

Any suggestions?


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Jim Howes
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Hi Jim You should not have a problem most retailers supply the software with the readers which will run on most OS's Networking is usually via rs232 cat5 or similar (baud rate is only low) . Try this for a start.

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From the limited experience of typical "software supplied" I have, it generally works only they way _they_ expect you to use it. If a device presents a basic serial stream down an RS-232 link, I can deal with that myself, although I'd be happier if the full specification was available so I can roll my own code.

I have already built a small flash-bootable linux 'distribution' (it's more like a kernel built specifically for this 486 board, enough libc to get bash running, and whatever stuff we want to run on it. Saves a lot of time mucking about with embedded SDK's and so forth, because if it runs on my desktop box, it will run on the embedded box. (That, and linux has a select() function which actually works, unlike a certain Redmondware OS)

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Thanks, will do.


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