Barcode Reader

11 Jul 2006 9:20 PM

Samuel Shulman

I would like to add barcode functionality to my POS program

How does one attach barcode reader is it usually USB port

How can the program get the data read by the device

Thank you,
Samuel

11 Jul 2006 11:26 PM

Steven Nagy

Hi

There are many different types of barcode scanners. USB and PS2 are the
most common.

I have experience with PS2 scanners. Essentially they plug in to your
PS2 keyboard port and act like any other keyboard device. When a
barcode is scanned, it sends the characters through as if they were
typed on a keyboard. So for example, if your win form has a textbox
that has the focus, and you scan a barcode, the characters appear in
the textbox.

To program against this, the best way is to handle the keypress events
native to a windows form or any other control. Usually a barcode will
need to have a * at the front and back for the barcode scanner to pick
it up, but this can be configured on most scanners as well. The * will
be removed by the time it gets to your app so you don't need to account
for it.

Essnetially you can differentiate from the barcode scanned text and the
keyboard typed text by checking the speed in which the characters come
in. If they come in super fast, then most likely those chars were
scanned, if they come in slower, then they were typed.

You also need to consider what barcode font to use, and then ensure
your barcode scanner supports that font. There are a few common ones,
but its best to use one that supports alpha and numeric chars. You can
get very cheap Code39 scanners and the font is freely available on teh
web to download

Hope this helps.

Steven Nagy

Samuel Shulman wrote:
Show quoteHide quote

> I would like to add barcode functionality to my POS program
>
> How does one attach barcode reader is it usually USB port
>
> How can the program get the data read by the device
>
> Thank you,
> Samuel

12 Jul 2006 11:09 AM

Theo Verweij

The USB versions work as below (keyboard wedge) or as an emulated serial
device, in which case, you can use the SerialPort from the toolbox to
get the data of the scanner.

Steven Nagy wrote:
Show quoteHide quote

> Hi
>
> There are many different types of barcode scanners. USB and PS2 are the
> most common.
>
> I have experience with PS2 scanners. Essentially they plug in to your
> PS2 keyboard port and act like any other keyboard device. When a
> barcode is scanned, it sends the characters through as if they were
> typed on a keyboard. So for example, if your win form has a textbox
> that has the focus, and you scan a barcode, the characters appear in
> the textbox.
>
> To program against this, the best way is to handle the keypress events
> native to a windows form or any other control. Usually a barcode will
> need to have a * at the front and back for the barcode scanner to pick
> it up, but this can be configured on most scanners as well. The * will
> be removed by the time it gets to your app so you don't need to account
> for it.
>
> Essnetially you can differentiate from the barcode scanned text and the
> keyboard typed text by checking the speed in which the characters come
> in. If they come in super fast, then most likely those chars were
> scanned, if they come in slower, then they were typed.
>
> You also need to consider what barcode font to use, and then ensure
> your barcode scanner supports that font. There are a few common ones,
> but its best to use one that supports alpha and numeric chars. You can
> get very cheap Code39 scanners and the font is freely available on teh
> web to download
>
> Hope this helps.
>
> Steven Nagy
>
>
> Samuel Shulman wrote:
>> I would like to add barcode functionality to my POS program
>>
>> How does one attach barcode reader is it usually USB port
>>
>> How can the program get the data read by the device
>>
>> Thank you,
>> Samuel
>

12 Jul 2006 2:15 PM

Brian Tkatch

Show quote Hide quote

> Hope this helps.
>
> Steven Nagy
>
>
> Samuel Shulman wrote:
> > I would like to add barcode functionality to my POS program
> >
> > How does one attach barcode reader is it usually USB port
> >
> > How can the program get the data read by the device
> >
> > Thank you,
> > Samuel

Steven Nagy wrote:

> Hi
>
> There are many different types of barcode scanners. USB and PS2 are the
> most common.
>
> I have experience with PS2 scanners. Essentially they plug in to your
> PS2 keyboard port and act like any other keyboard device. When a
> barcode is scanned, it sends the characters through as if they were
> typed on a keyboard. So for example, if your win form has a textbox
> that has the focus, and you scan a barcode, the characters appear in
> the textbox.

Indeed. I was just playing with one of these last night.

> To program against this, the best way is to handle the keypress events
> native to a windows form or any other control. Usually a barcode will
> need to have a * at the front and back for the barcode scanner to pick
> it up, but this can be configured on most scanners as well. The * will
> be removed by the time it gets to your app so you don't need to account
> for it.

If that so? I was scanning barcodes in with the PS/2 keyboard wedge and
did not see any *s, whether in the console or in a textbox.

> Essnetially you can differentiate from the barcode scanned text and the
> keyboard typed text by checking the speed in which the characters come
> in. If they come in super fast, then most likely those chars were
> scanned, if they come in slower, then they were typed.

Unless the user cut&pasted the text, in which it comes in very fast.

> You also need to consider what barcode font to use, and then ensure
> your barcode scanner supports that font. There are a few common ones,
> but its best to use one that supports alpha and numeric chars. You can
> get very cheap Code39 scanners and the font is freely available on teh
> web to download

CueCat! :)

B.

12 Jul 2006 10:48 PM

Steven Nagy

> If that so? I was scanning barcodes in with the PS/2 keyboard wedge and
> did not see any *s, whether in the console or in a textbox.

No the scanner removes the *'s before sending it down the line.
This is configurable as well. Generally you can download a set of
barcodes from teh manufacturer's website that, when scanned, setup the
barcode scanner to different settings.

> Unless the user cut&pasted the text, in which it comes in very fast.

In this case, the key's being pressed are CTRL + V which are what would
be captured.
NOT the actual string buffer that was copied originally. So it should
still work.

13 Jul 2006 2:31 PM

Brian Tkatch

Steven Nagy wrote:

> > If that so? I was scanning barcodes in with the PS/2 keyboard wedge and
> > did not see any *s, whether in the console or in a textbox.
>
> No the scanner removes the *'s before sending it down the line.
> This is configurable as well. Generally you can download a set of
> barcodes from teh manufacturer's website that, when scanned, setup the
> barcode scanner to different settings.

Perhaps each scanner is different. I didn't install any drivers for
this one.

> > Unless the user cut&pasted the text, in which it comes in very fast.
>
> In this case, the key's being pressed are CTRL + V which are what would
> be captured.
> NOT the actual string buffer that was copied originally. So it should
> still work.

Or Shift-Insert.

What if the past is effected programmatically, as through a
right-click, or through sendkeys?

B.

13 Jul 2006 11:59 PM

Steven Nagy

You'd really have to test it, but possibly the right-click -> paste
might cause the keypressed event to fire, but I still doubt it. I guess
some tests are in order!
I'll run some on the weekend.