Magnetic card reader meaningless data

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I have a MSR206 card reader device, and I wrote an application to write data on it in C#:

SerialPort sp = new SerialPort(driveletter);
List<byte> bytes = new List<byte>();
            bytes.Add(0x1B);
            bytes.Add(0x77);
            bytes.Add(0x1B);
            bytes.Add(0x73);
            bytes.Add(0x1B);
            bytes.Add(0x01);
            bytes.AddRange(Encoding.ASCII.GetBytes(u));
            bytes.Add(0x1B);
            bytes.Add(0x02);
            bytes.AddRange(Encoding.ASCII.GetBytes(p));
            bytes.Add(0x1B);
            bytes.Add(0x03);
            bytes.AddRange(Encoding.ASCII.GetBytes(o));
            bytes.Add(0x3F);
            bytes.Add(0x1C);
SendBytes(sp, bytes.ToArray());

static void SendBytes(SerialPort sp, byte[] bytes)
        {
            try
            {
                if (!sp.IsOpen)
                    sp.Open();
                sp.Write(bytes, 0, bytes.Length);

                Console.WriteLine("Bytes sent...");
            }
            catch (Exception ee)
            {
                Console.WriteLine(ee.Message);
            }
        }

This should write 3 strings on the 3 tracks, but when I try to read the datas from the card it gives back meaningless informations. (the device sends back a "WRITE OK", so the writing was succesful)

Posted 4-Aug-12 23:23pm

velvet7

Updated 4-Aug-12 23:30pm

v4

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OriginalGriff 5-Aug-12 5:25am

The code fragment you supplied writes nothing to the card - it purely puts data into a List.
Edit your question, and show the data write fragment as well.
Use the "Improve question" widget to edit your question and provide better information.

velvet7 5-Aug-12 5:29am

Updated.

1 solution

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OriginalGriff · Answer 1 · 2012-08-04T23:42:00

Solution 1

Without the actual hardware it is difficult to tell what the problem is, but a quick look at the manual suggests that it uses 5 bit data - so lowercase values are not going to work (Page 9-2 of the PDF version) as they don't exist.
Have you tried numeric values? Or checking what the test program they supply does?

Posted 4-Aug-12 23:42pm

OriginalGriff

Comments

velvet7 5-Aug-12 5:52am

I checked the test program too, but same thing. Though I tried with numeric values, and they were just working fine. But when I tried to read the card the text appeared like this:%123? So how could I write on the card without the start and the end characters? I mean, I don't want the % and ? character to appear after reading.

OriginalGriff 5-Aug-12 6:19am

Look like from the manual that the data is always enclosed in '%' and '?' or ';' and '?' characters - so strip them off when you read them back - I don't think you can suppress that.

velvet7 5-Aug-12 6:22am

Yeah, but the point of this whole thing is to directly write this data to an application on another computer. So this '%' and '?' would screw the whole thing up.

OriginalGriff 5-Aug-12 7:13am

So encapsulate it.
Create a class which conmtains teh connection, and has a "WriteString" and "ReadString", or "WriteData" and "ReadData" methods.
They can talk to the reader, and encode date and strip data as necessary. Your external progamms talk to your class rather than the reader itself.

Much tidier approach anyway!

velvet7 5-Aug-12 7:18am

I don't really understand you, the start character and the end character would stay there.

OriginalGriff 5-Aug-12 8:18am

No, the idea is to divorce the hardware (the reader, the serial port) from the software (the application) by providing a data-focussed class which accepts a string (or set of bytes, or whatever the data represents as far as teh application is concerned) and provides the same back.
The new class handles conversion of data from the App centric format to something the reader understands, and converts the raw data from the reader to something the App understands.

It's similar to the way a Button works - you provide a text string, and it provides a Click event. You don't have to worry about making it look like it moves down when the user presses a mouse button over it - it knows how to do that, and just tells you when teh user does something.

velvet7 5-Aug-12 14:02pm

Alright, but if I send to the device that it should write bytes to the card, then it will write the start character no matter what. It's nothing something I can control, as far as I know. But shouldn't the decoder decode it to remove the start and end characters? Maybe I screw up something, because when I try to read from the card it doesn't read the real informations, it reads just 0's, so I think the data is encoded, but I don't want it to be encoded.

OriginalGriff 6-Aug-12 3:12am

Then you need to do the encode / decode in you class as well.

For the moment, I would concentrate on getting data of any form reliably written and read from the card.
Do you get the source of the test program, or just the EXE?

velvet7 6-Aug-12 3:47am

Just the exe. But anyways, I figured out another way, the reader device sends the data as plain text(sends data like a normal keyboard), so I just read with the lowlevelkeyboard api, and prevent it from writing by returning 1 in the HookCallBack method, so the cardreader won't write anything but I am still able the read out what it wants to write.

OriginalGriff 6-Aug-12 3:54am

Most do. It tends to be the default setting so they can be plug and play as a card reader with any software.