(Solved)Ignition Scada Barcode Scanning Problem to AB

JeremyAdair

Member
Join Date
Nov 2016
Location
NWA
Posts
8
I have ignition running on a PC. There is a barcode scanner app from Sepasoft that allows an PC running ignition to accept barcodes. It costs 500 bucks to enable it on the whole ignition server.

Their documentation is garbage! It has a pretty picture though. Googlers will need this code put into the OnBarcodeRecieved event in the scripting of the barcode component.

print "onBarcodeReceived called..."
result = event.toDict()
barcodeText = result['Default'][0]
print "onBarcodeReceived barcode = %s" %(barcodeText)

tagPath = "TESTERS 9 AND 10/Pretest_Barcode_Scan"
#print tagpath
system.tag.write(tagPath, barcodeText)

Also be aware if you get the barcode addon from sepasoft there will be two barcodes in your component pallet in ignition. The one you need will be at the very bottom of the pallet.

Now I have spent a full month fighting this barcode scanner. It was not working properly and missing scans. I finally found it.
There are these things called scan classes in Ignition. I change my default tags to Leased at the start of every project.

Leased tags have a fast and slow tag update rate. It is slow if nothing is using the tag. It is fast if there is a screen using the tag.

The problem I believe I found is that my tag on the barcode component is not continuously running on the screen. I changed my PLC tag from leased to driven(auto poll at one speed) and all of my barcode problems went away.

The problem I was having was consecutive fast barcode-scanner scans would drop data. I had the client PC open on the console with barcode debug logs set to debug. The debug log had everything coming in fine and I could see every character that ignition processed. My Plc would not get the data but ignition said it sent it.

Since I do not have ignitions phone support I hope to contribute this info to the community here. It bit me.

Good luck guys
 
Last edited:
Well, thanks for the information!


If you haven't looked deeply into scan classes, you might want to soon. I probably have 15 or 20 different scan classes on my server, and I use them all. Predominantly, I use one I call "Controls_Leased_Fast" for push-buttons, "Controls_Leased" for general setpoints that has Optimistic Writes enabled, but I also have a bunch configured for mainly read-only information, or various historical polls.


You probably do not want DRIVEN for your bar code tag, but instead DIRECT.



The Direct scan class executes unconditionally at a fixed rate, while Driven allows you to effectively control the poll rate based on another tag or expression.



Driven is handy especially if you really honestly want variable speed scan classes; I use some driven classes to expressly watch for line startup and shutdown conditions. If you set the Driven class for "Any Change", you completely ignore the poll rate for the class, and scan the item literally on any change of the driving tag.


For a completely asynchronously triggered bar-code reader, not attached to any particular screen, you might also want to set the scan class for "Read" rather then "Subscribed" mode. This will make the timing of that actual read independent of any others.
 

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