Maybe someone could enlighten me on this subject, Im looking into if regular credit card machines (they should be able to) could read id cards (any card with a magnetic stripe). I was wondering how these cards are encoded when posting to a certain web service/network (do they encode the IP gateway?)...and if there was an api or some literature into processing magnetic stripe info.
A credit card machine probably can read the strip on any card, but it won't know what to do with the data if it isn't in the proper format. The strip is usually a multi-track strip with 3 tracks. The card number, name of the card holder, and other stuff is usually encoded using track 1 with track 2 being some subset of the track 1 data.
An ID card might use a different data format. It is just a strip of magnetic tape that can be read with a card reader. You can probably buy a reader online for under $10. I've seen these come as 9-pin RS232 serial devices, but they'll mostly come as USB type devices that emulate a keyboard. When you swipe the card, the reader acts like you typed the data in.
As for encoding an IP address....maybe, but it is unlikely. Things like addresses that can be transient would be better not to put on all the cards you are issuing to people. Otherwise, when you change the IP you have to re-issue all the cards. Your best bet is to read the card and see what is in the data.