News & Events

Axode Barcode Grading

The SRE protocol has not change, we will leave it at 6.

What has changed is the way we handle the result itself.

We can now apply a “structure “ to the window result, telling it to add the grading and the separator we want.

So this structure is stored in the WRS keyword.

In our case we want:


–     1st digit is the camera # (1 here)

–     987654321 is the result of Win1 on Cam1

–     30 is the grade (B)

–     123456 is the result of Win2 on Cam1


So we will have to have:

– SRE=6

– WRS=r.p (r says we want to sent the result, and p says we want the grade in numeric format, if we wanted it in Alpha format we would have entered q)

– “Quality” parameter set to 1 (under Window/Process)


NOTE: Even though we show the grade in a letter format on the screen, we will sent it in numeric format on the RS232.


Here is the numeric to letter format conversion table:

A = 4.0 (40)
B = 3.0 (30)
C = 2.0 (20)
D = 1.0 (10)
F = 0.0 (00)


Here is a screenshot of a good grade:



And a snapshot of a barcode that failed (under the threshold set by the operator on the Axode system):



NOTE: In our case, with the GT controller, we won’t setup a threshold in the Axode, but in the GT controller itself, by creating a “limit” control like we do with presence for example.


As far as control, here are the 7 ANSI based controls that we ensure:


Edge determination (pass / fail) :
According to the codification, it checks that we have enough transition for each scan.

We make sure those transitions correspond to a start bit + at least 1 digit + a stop bit.

Minimum reflectance (pass / fail) :
We check here that the minimum reflectance of a black line is at least ½ the maximal reflectance (of the paper; on white spaces between bars).

Symbol contrast (graded) :
This is the difference between the maximal reflectance value, and the minimum reflectance value.

Minimum edge contrast (pass / fail) :
this is the reflectance difference between the « lighter » dark bar and the “darker” white space. It must be over 15%.

Modulation (graded) :
“modulation” = “minimum edge contrast” / “symbol contrast”.

Defects (graded) :
This is given by the size of voids in black bars, and spots in white spaces.

Decode (pass / fail) :
We make sure we can decode the barcode.


Pass/failed: A or F

Graded: from A to F


For each scan, we calculate the “scan grade”. The scan grade is the lower mark given by the 7 controls above.

Then, we determine the “symbol grade”: average of all the scan grades.