Hello there, I've got some questions about reading barcodes and magstripes in assembly. First of all I see a big difference in the prices of three models of a slot barcode readers . Here is the information I got about these three different models:

SLR-700T TTL, Undecoded
SLR-700K AT/PS2 Keyboard Wedge, Decoded
SLR-700R Serial RS-232, Decoded

So this is the information I got on these readers, but what the hell does "TTL, Undecoded" or "Decoded" mean? There is a quite big difference in the prices of these three models and no detailed information of their capabilities, etc.

Second, which is better, easier to program, cheaper - barcode ot magstripre. What are the pros and cons for both technologies? I'm doing a very simple project and I'm indifferent to the type of the reader - barcode or magstripe, but I want the cheaper device, I want the cheaper plastic cards and the easier way to communicate with the device, of course.

Any information on this topic is greatly appreciated :-)

Posted on 2005-08-08 22:39:35 by siddhartha

easiest to use is DECODED as it'll give you ASCII characters which you can read via the RS232 port (RS232 version) OR characters that appear as if they were type at the keyboard (keyboard wedge version).

The undecoded version will give you the raw optical output from the barcode scanner and you'll have to decode it yourself. This isn't worth the effort unless you intend to make lots of these devices and build them into some custom product of your own.
TTL will be the logic signal levels provided from the device. 0.4-2.4V at a few milliamps, although usually you'll get 0-5V out of them.

Undecoded is cheaper because it doesn't include the microcontroller and interface logic, only the barcode scanner mechanism.

I reckon barcodes are better than magstripes because you can print barcodes without any special equipment, just a normal printer.

Posted on 2005-08-09 06:23:21 by pdixon
To add to what pdixon said:

the "AT/PS2 Keyboard Wedge, Decoded" version will plug into your computers AT/PS2 keyboard port, then your keyboard will plug into the Wedge.  In this way, the decoded--ASCII--codes from the reader are stuffed into the computer as keyboard input.  This is convenient if the input from the reader is going right into an edit control.  For instance, if your barcoded or magstripe info is for a user id #, at the point where your program prompts for a user id #, your Keyboard Wedge will send its' output directly into the user id # edit field.

Since the regular keyboard plugs into the Wedge, any keystrokes are passed thru to the computer.

With the serial port version, you would have to have program code waiting for the ASCII code to arrive at the serial port, read it, and then transfer this input into your edit control.


Posted on 2005-08-09 09:05:54 by farrier
Thanks for the useful information fellows! I greatly appreciate it :) BTW is it necessary to have direct hardware access to receive the information from the barcode reader? Or I should interact with the drivers? Or there is some standard way of doing this?

Posted on 2005-08-09 12:20:01 by siddhartha
Do you mean to read the COM port?
Posted on 2005-08-17 18:23:31 by x86asm