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How to check the operator has scanned the correct Barcode before starting a test.

One of the problems we had was that a customer wanted 3 different barcodes to be scanned before the product was tested, each barcode was made up of differing lengths and characters so the challenge was to make sure the operator scanned the correct barcode when asked. This data was then used to print labels with the correct barcode being in the right place.

Now this is possible using ‘Regular Expressions’ but complicated for some people to understand, so we developed a new coding system for barcodes and let the SubVI take care of converting the easy code to a regular expression.

The easy code is as follows

Character Description
A Any Alpha Character
N Any Numerical Character
X Any Alpha-Numerical Character
() Dedicated Character


NOTE – You should take precaution using the ‘X’ character as this is a lazy check and could make the definition more prone to false positives, and these are the only characters you can use to define the barcode makeup, you may add symbols like * directly if needed

() Dedicated characters mean at that position there will always be this character.

So let’s see what the definition code would be for a barcode, we will use SP0025AS as an example, the ‘SP’ at the beginning will always stay the same. ‘0025’ is a number and will change from barcode to barcode and finally, ‘AS’ the ‘A’ can change to a number as well as another letter, the ‘S’ can change to another letter only.

So our example barcode make up is as follows, (S)(P)NNNNXA and is 8 characters long, this is the string you would input to the SubVI along with the scanned barcode, then process the output ‘Barcode is Matched’ for a Boolean ‘True’


Of course our input barcode definitions come from a Database and the routine is more automated than this.

I hope this helps someone, Ask questions if needed. (34.8 K) LabVIEW 2010