Wednesday, August 25, 2010

Verifying Data Matrix codes

Let’s be clear about this, verifying a code is not the same as reading it. Reading means extracting the encoded information whereas verification consists of determining the quality of the marking.

“Why should I care?” you ask. “If my customer and I can both read the code, doesn’t that mean the marking is good?”

Well imagine that your customer calls you up and says he can’t get a good “read” on your data matrix codes. What do you do then? Most likely you pick a freshly marked part off the end of the line and scan it. “Yes, you say, I can read that,” but is that a sufficient test?

The problem is that your reading setup might be completely different to your customers. You might be flooding the part with monochromatic light and have the lens aperture stopped all the way down while your customer is using a handheld reader in a warehouse.

This is why we have standards for verifying data matrix codes. If you can show that your mark is good, as defined by international standards, then the problem is with your customer. But without standards your customer might push you into making expensive changes to your processes.

I recently stumbled across an excellent summary of the relevant standards on the “Test & Measurement” web site. “New standard improves verification of Data Matrix codes,” dates from February 2007, so it’s not new, but the information is still good. In particular, there are a number of links to the relevant standards. I strongly encourage you to make use of them.

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