Troubleshooting Barcode Data Transfer Issues

[bobuhh98]

Hello, 

I am a relatively new Controls Engineer looking for some guidance on an issue I am having with transferring barcode scanner data. 

Some quick bits of information: 

Allen Bradley CompactLogix 5380 v 35

Zebra Barcode Scanner DS3608 

EA3600 Ethernet Firmware v 001-R08

 

I am trying to collect barcode data from the scanner and move it to another tag that is a string. The issue is that the data will very occasionally come through as "$00$00$00....". I am wondering if this is a PLC issue, or potentially a configuration issue with the scanner. 

 

How I am currently doing it 

CPS: Source - Scanner.Data[0]; Dest - Scanner2.Data[0]; Length - Scanner.LEN

Both Source and Dest are SINTs. Source is Controller level, Dest is local. 

 

The data is later moved again using the MOV instruction 

MOV: Source - Scanner2; Dest - Scanner3 (a UDT) 

[Ken Roach]

I have not used that Zebra unit before, but at first blush this sounds like an RPI timing issue or just a mistake at designating the length.

Does the Zebra provide some kind of "new data present" or handshake to let the PLC know that there's a new symbol decode string in the Input data table ?   Do you execute that CPS instruction every single scan ?

The Scanner.Data[x] SINT array is the Input tag itself, correct ?    

Do you know what the Zebra is set to do in the event of a bad decode ?   
 

I would take a step back and look at how the Input data changes when there's a new decode.      You could also maybe troubleshoot by putting a "if .LEN >0" condition on the CPS instruction.

Because the source is a simple SINT[x] array input tag, and the destination is an ordinary STRING, there shouldn't be any of the v36+ question about the length of data depending on the size of a UDT that's involved.

[BachPhi]

I have to give credit to the Zebra engineers — they really made this barcode scanner way more complicated than it needs to be. Next time, I’d recommend going with the RTA 435NBX — it’s truly plug-and-play. Feel free to try out my code below.

 

NEQ bcScanner:I.UpdateCounter LastCounter BST COP bcScanner:I.Data[0] BarcodeReadData[0] bcScanner:I.BarcodeLength NXB MOV bcScanner:I.UpdateCounter bcScanner:O.AckCounter NXB MOV bcScanner:I.UpdateCounter LastCounter BND