How to force Barcode scanning input ONLY?

[WillowMobileSys]

I have a need for employees to Clock In by scanning a Barcode for the location they are at.  The employees can travel to any one of a number of locations to perform work.  Each location has its own Barcode posted at the facility. 

The intent is to not just provide the time and location but also that they are physically at the location when they Clock In. 

The issue is that in order to perform Barcode scanning, the Barcode field must Show and be Editable.  However, if the use cancels out of the scanning screen, they return to the form to an empty Barcode field.  I'd like to prevent manual input into this field forcing the user to start over and actually scan the Barcode.  As far as I can tell, I have no way to disable/prevent input into the Barcode field. 

Does anyone have a suggestion of how I can prevent manually typed input into this Barcode field after they have cancelled out of scanning?

[WillowMobileSys]

Still looking for a way to force scanning ONLY w/validation ....but the below is slightly Interesting!!!

I had been playing with this Barcode field trying different things.  For example, I tried to insert a Yes/No expression using the IN() function like this:

IN([_THIS], Locations[Barcode])

 I wanted just a straight validation with no dropdown presented.  However, this was treated just like having a validation list - dropdown and all.

BUT, just for fun I tried this:

AND(IN([_THIS], Locations[Barcode]), TRUE)

AND IT WORKED!!

I do NOT get the dropdown but the typed value is validated against the list as expected.

Is this another one of those hidden workarounds??   I dunno, but I am running with it.

[Steve]

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@WillowMobileSys wrote:

Is this another one of those hidden workarounds?? 

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Yep, this is the "correct" way to validate against a list without the magic dropdown.