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VRF Integrating a bar code reader

Question asked by VRFuser on Nov 25, 1997
Item Subject: Re: Integrating a bar code reader
     Mr Weeks,
     GVG is completely correct is his statement.  As a programming issue,
     you do have several choices. 
     A) Pop up dialog boxes can be used.  The built in ones are often
     modal, meaning the application stops until the dialog box is closed. 
     Some system-designs may not like this.  The modal boxes do have a
     timeout feature most of the time though, so there's a trade-off.  In
     addition, built in dialog boxes, to my knowledge, will not close until
     you press the 'ok' button. So, the user will not be free of touching
     the keyboard, though they won't have to type on the keyboard for the
     barcode number.
     B) Another solution is to control this activity via VEE code that you
     design.  You can create a user-object that pops up to the user.  The
     user object can contain a text-box.  The text box can be configured to
     'wait for input'.  When the bar code reader is used, it will send a
     'CR/LF' as a terminator when it scans a bar-code.  Must bar-code
     readers allow you to configure the terminator, and by default send a
     LF.  Or, the user can still type the entry and hit return.  In either
     case, you code should process this input (being attached to the
     execution-done terminal of the text box) and then exit the user
     object.  This effectively eliminates the user from even having to
     touch the keyboard during this activity.  When you configure that text
     box to 'wait for input'  the cursor will be active in the text box
     when the 'VEE' execution reaches you text box.  You can have multiple
     bar-code entries take place on the same panel: you have to control the
     program flow yourself via the way you connect up the objects. 
     Programming a timeout into this kind of object is very delicate if you
     think about it for a bit, but since you program is not interupted with
     this style, not having a timeout may not be a big problem (non-modal
     I hope this provides some tips.
     Andrew Hamilton

______________________________ Reply Separator _________________________________
Subject: Re: Integrating a bar code reader
Author:  gvg-at-lvld ( at HP-PaloAlto,shargw6
Date:    11/26/97 10:42 AM

> Hello,
> Has anyone integrated a bar code reader into their system?
> I am considering implementing one and I am curious if there is someone out
> there who has gone through the implementation.
HP barcode readers, at least, simply splice into the PC keyboard port and
there is no noticeable difference between that and keyboard input.  Using
pop-up dialogues would seem to be a useful scheme.
[<>] regards -- gvg
> Troy Weeks
> Aval Communications
> Walnut Creek, CA