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Standard input and card reader data

Posted on 2004-04-27
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Last Modified: 2012-05-04
This is my first time working with a card reader.  Where does standard input from a card reader go when focus not set on a text box?  Is there a way to monitor it?
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Question by:MariaHalt
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by:mmusante
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What kind of card-reader are you using?

I used 'winscard.dll' for some test take a look here ...

(http://search.microsoft.com/search/results.aspx?view=msdn&st=b&na=82&qu=winscard&s=1&swc=4)
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by:MariaHalt
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Make: MagTek
Part No. 21080204
Desc: MINI WEDGE MSR,TRKS 1 & 2: BLACK W/CABLE FOR AT AND PS2
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mmusante earned 125 total points
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Sorry I supposed you were using a different kind of card-reader ...

If your card-reader works as keyboard things would be easier ...

To read the keyboard (and the card-reader) without worring of the control who have the focus you can set the KeyPreview property of your form to True so the keyboard events of your form (KeyDown, KeyUp & KeyPress) will be fired to the form first and then to the controls inside of it

try something like this ...

Private Sub Form_Load()
    ...
    me.keypreview = true
    ...
and sub

Private Sub Form_KeyPress(KeyAscii As Integer)
   ...
'   < handle here your card-reader typing >
   ...
End Sub
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by:MariaHalt
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I did as you suggested, however the Form_KeyPress event was only triggered the first time I swiped the card.  I did not receive the message on subsequent swipes.  My code is simple (at the moment):

Private Sub Form_KeyPress(KeyAscii As Integer)

MsgBox "in Form_KeyPress event"

End Sub

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by:mmusante
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KeyPress is fired for each key pressed ...

try this to see how it works with your card-reader ...

Private Sub Form_KeyPress(KeyAscii As Integer)
   debug.print asc(keyAscii)
End Sub
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by:mmusante
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Sorry ...

Private Sub Form_KeyPress(KeyAscii As Integer)
   debug.print chr(keyAscii)
End Sub
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by:MariaHalt
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Tried, debug.print chr(keyAscii), as you suggested.  Nothing happened at all when I ran it normally.  I then inserted a breakpoint at that line, something interesting happened.  The numeric data from the card appeared as the first line of code followed by the word Print.  See below:

Private Sub Form_KeyPress(KeyAscii As Integer)

910004061 Print 'This wasn't  there before!!!
Debug.Print Chr(KeyAscii)

End Sub

FYI:  The data on the card is a combination of alpha-numeric characters, ;910004061?
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by:mmusante
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take a look here (http://www.experts-exchange.com/Programming/Programming_Languages/Visual_Basic/Q_20952404.html)

It could be useful to separate card-reader data from keyboard typing
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Author Comment

by:MariaHalt
Comment Utility
There will be no keyboard typing.  I'm using a touch screen monitor.  The card reader works like my keyboard.  

Let me reiterate my problem, I want to capture data from a card reader.  The data is an alpha-numeric string.  The data is easily captured when my text box has focus, but my concern is detecting a swipe when the text box does not have focus.  I want any data read contained somewhere no matter what control has focus.

I appreciate your help.  Looking forward to your response!
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by:mmusante
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>>>The numeric data from the card appeared as the first line of code followed by the

it sounds very strange ... the debug.print instruction print a message in the immediate window (press ctrl-G to show it)
here for something more on debug.print (http://home.no.net/svbug/emner/debug_immediate.htm)
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by:MariaHalt
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Yes, I thought it would appear in the immediate window also, but it did not.
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by:mmusante
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try this ...

Private Sub Form_KeyPress(KeyAscii As Integer)
   txtYourTextBox.Text = txtYourTextBox.Text & chr(KeyAscii)
End Sub

replace txtYourTextBox with your real textbox name

(you have to decide how and when clear your textbox)
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by:mmusante
Comment Utility
>> Yes, I thought it would appear in the immediate window also, but it did not.

the break-point had put the focus on your code window then the card-reader wrote on your code
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by:MariaHalt
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Ok, tried your suggestion,  txtYourTextBox.Text = txtYourTextBox.Text & chr(KeyAscii).  Replaced txtYourTextBox with my text box's name.  This is what happened.

When the text box had focus the following appeared in it:
?160400019;;9100014061?.  (A mirror of itself).

I reran it, put focus on something other than the text box and the following appeared, ;910004061?.  This is much better.

I going to try this:  make the text box invisible, capture the data there (since it can not have focus), thus containing the card data there.

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Expert Comment

by:mmusante
Comment Utility
set the 'Locked' property of the textBox to true ... so you will write only by the kepress event
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Author Comment

by:MariaHalt
Comment Utility
Well I think I finally have it doing what I set out to do,  capturing all card data, regardless of what has focus.  Having set the form's keypreview to true, as you suggested, I created a dynamic array that will hold each character when the form's keypress event is triggered:

Option Explicit
Private rayCardData() As String

Private Sub Form_Load()
ReDim rayCardData(0)
End Sub

Private Sub Form_KeyPress(KeyAscii As Integer)
Dim intArrayIndex As Integer

Select Case KeyAscii
    Case 48 To 57, 59, 63 'Acceptable characters for array
        intArrayIndex = UBound(rayCardData)
        ReDim Preserve rayCardData(intArrayIndex + 1)
        rayCardData(intArrayIndex + 1) = Chr(KeyAscii)
    Case Else
        'Ignore any other characters
End Select

Thank you for your help.

End Sub
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