How catching a barcode device !!

Thread view:

Enable EMail Alerts

Start New Thread

Thread rating:

tiziano fabbri - 26 Apr 2006 20:20 GMT

Hi , I'm finishing a new project and a new request is to catch a Ps2,
simulated keyboard, barcode device. My application is a console application
without forms or others kind of user interface. Also I have a serial
communication in a thread with a several priority, a ftp server always in
listening status and is possible to run a tool to communicate by second
serial. Alls is concentrate inside a 486 100MHz and 32Mbyte of RAM.
Using 'GetAsyncKeyStatus' I have some problem because I loose sometime key
status if I use a normal thread priority, if I increase the priority I loose
lot of time in the serial communication.
Someone has some tips for me or is prefer to use other kinds of device,
serial for example ?? thank you very much, fabbrit

Reply to this Message

Paul G. Tobey [eMVP] - 26 Apr 2006 20:33 GMT

Huh? It sounds to me like you've chosen very poorly in how you connect
things. Trying to use GetAsyncKeyStatus() is a *hopeless* way to try to
catch every key as it arrives. It seems like you should have chosen a
different way to connect the barcode scanner, so that you could control the
communication with it (serial comes to mind).

However, since you're probably stuck with what you have, use a low-level
keyboard hook to trap all keyboard events in the system (you'll have to do
this in native code, I think). For each keypress, you can then do whatever
you need to do, drop the key in a queue for serial transmission or whatever.

Paul T.

> Hi , I'm finishing a new project and a new request is to catch a Ps2,
> simulated keyboard, barcode device. My application is a console
[quoted text clipped - 9 lines]
> Someone has some tips for me or is prefer to use other kinds of device,
> serial for example ?? thank you very much, fabbrit

Reply to this Message

tiziano fabbri - 27 Apr 2006 05:37 GMT

Hi Paul,

have some example or tip regarding low level way (evC++ I think!?!).

> Huh? It sounds to me like you've chosen very poorly in how you connect
> things. Trying to use GetAsyncKeyStatus() is a *hopeless* way to try to
[quoted text clipped - 22 lines]
> > Someone has some tips for me or is prefer to use other kinds of device,
> > serial for example ?? thank you very much, fabbrit

Reply to this Message

David Owen - 27 Apr 2006 12:17 GMT

Did the manufacturer of the device you're using provide a library for using
their device? Normally that's the best mechanism available.

David

> Hi Paul,
>
[quoted text clipped - 32 lines]
>> > Someone has some tips for me or is prefer to use other kinds of device,
>> > serial for example ?? thank you very much, fabbrit

Reply to this Message

Paul G. Tobey [eMVP] - 27 Apr 2006 16:52 GMT

You need a low-level keyboard hook. Here's some code that I've posted
previously that shows how I call it in a native-code DLL.

http://groups.google.com/group/microsoft.public.dotnet.framework.compactframewor
k/browse_frm/thread/b991802a15291ced/7d8815aa46a22ecc?q=low+level+keyboard+hook&
rnum=3#7d8815aa46a22ecc

Paul T.

> Hi Paul,
>
[quoted text clipped - 32 lines]
>> > Someone has some tips for me or is prefer to use other kinds of device,
>> > serial for example ?? thank you very much, fabbrit

Reply to this Message

tiziano fabbri - 28 Apr 2006 05:37 GMT

Hi Paul, Hi David,

thanks for your help and interesting.

to Paul: I'll try to use yours tips and the documents that you got me the
coordinates, thank you very much.
I'll send you some news in a few days

to David: tha barcode device is a very normal PS2 keyboard that simulate
keyboard inlet. No docs;

bye, fabbrit

> You need a low-level keyboard hook. Here's some code that I've posted
> previously that shows how I call it in a native-code DLL.
[quoted text clipped - 39 lines]
> >> > Someone has some tips for me or is prefer to use other kinds of device,
> >> > serial for example ?? thank you very much, fabbrit

Reply to this Message

How catching a barcode device !!

Free Magazines