Motorola XR400, not getting any tags

Questions about Rifidi Workbench

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Nervin
Posts: 18
Joined: Tue Aug 03, 2010 3:46 pm

Motorola XR400, not getting any tags

Post by Nervin » Wed Aug 04, 2010 3:18 pm

Hi Guys,

I started working on Rifidi platform and and I was able to get an Alien ALR-9650 to work no problem, but I can't get a Motorola XR400 to work. From workbench I add an LLRP reader, with the Ip of the XR400 and port 5084. I create a session, add a LLRP_Configure command, with Read Mode set to POLL. As soon as I submit the command(icon goes green), I see the Motorola amber light go on, which means that it is reading tags. I then send a LLRP_poll command, but I get no tags in Tag View. I noticed the error below on the console, maybe it is related. I tried using the XR400 simulator, but it does not mention LLRP support. Thanks for any help or links to guides I can follow

"There was a problem when parsing LLRP Tags. tag has not been added
org.apache.commons.codec.DecoderException: Odd number of characters."

kyle
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Name: Kyle
Organization: Pramari
Location: Hartford, CT
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Re: Motorola XR400, not getting any tags

Post by kyle » Thu Aug 12, 2010 9:23 am

Yea, that's certainly a problem. Do you have a different tag that you can try? Also, is there any more information around that error such as where it's happening?

Nervin
Posts: 18
Joined: Tue Aug 03, 2010 3:46 pm

Re: Motorola XR400, not getting any tags

Post by Nervin » Tue Sep 14, 2010 1:12 pm

I upgraded to Edge server 1.2, added the Motorola XR400 using the LLRP adapter and it worked right away. It worked using READ and PUSH modes. Thank you for the updates on LLRP.

Matt
Posts: 362
Joined: Fri May 02, 2008 11:56 am
Organization: Pramari

Re: Motorola XR400, not getting any tags

Post by Matt » Thu Sep 16, 2010 11:21 am

Hi Nervin,

Glad to hear things are working on your end now. Most likely the problem stemmed from the tag you were using having leading zeros, which we were not handling correctly before 1.2.

andres.contreras
Posts: 8
Joined: Fri Mar 25, 2011 10:05 am
Organization: Servicios de Automatizacion RFID C.A.

Re: Motorola XR400, not getting any tags

Post by andres.contreras » Fri Mar 25, 2011 11:04 am

Hello guys,

I've been working with the RiFiDi solutions for a while and my company has offered solutions using the RiFiDi Edge Server, we are very satisfied with your solutions. I post this because I recently encountered a problem when I read tags with the Impinj Speedway Revoltion R420. The Edge Server 1.2 throws the same error mentioned in this thread when I try to read a tag with leading zero's. The weird part is that not all tags have the same issue. I've succesfully read EPC codes like e50004 from Alien Squiggle tags, but can't read codes like 1110 or 1120 from the same type of tag. I read any EPC code generated by the emulator without errors, so it seems the LLRP plugin is not working perfectly with the Impinj R420. Could you please tell me if you also encountered this issue before? What's your recommendation? Should I modify the LLRP plugin? I attach an image with the console error.

Thanks in advance.
Attachments
Error_EdgeServer.jpg
Error shown on the edge server console after tag enters the read zone
Error_EdgeServer.jpg (231.76 KiB) Viewed 12057 times

Matt
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Organization: Pramari

Re: Motorola XR400, not getting any tags

Post by Matt » Wed Mar 30, 2011 5:41 pm

Hi andres,

Nice catch. It seems to be a problem with the library we use to parse the hex values - it can't handle leading zeros it seems. Unfortunately there isn't a great solution to the problem at this time - what is really needed is a modification to the parsing section of the LLRP plugin to handle those values correctly. You could do that yourself, but in our current version there isn't a great way for users to export core plugins. We are working on making exports less painful for the next release already, and I'll be sure to hit that LLRP bug.

Just so we are on the same page, could you give me some full values for tags that work and tags that don't work so I can try them out myself?

Sorry I couldn't be of more help,
Matt

andres.contreras
Posts: 8
Joined: Fri Mar 25, 2011 10:05 am
Organization: Servicios de Automatizacion RFID C.A.

Re: Motorola XR400, not getting any tags

Post by andres.contreras » Thu Mar 31, 2011 11:29 am

Hello Matt,

Thank you for your answer. The problem is at the Hex.decodeHex(char[] arg0) function in the line 209 of the LLRPEventFactory class of the LLRP reader plugin (as shown in the exception). This function receives an array of Hex character that represent bytes, but since they are Hex characters, each represents half byte, so if the function receives an odd number of characters it throws that exception. Since I don't mind the extra zero in the EPC code I did this:

Original code:

private static BigInteger parseString(String input) {
BigInteger retVal = null;

try {
input = input.trim();
retVal = new BigInteger(Hex.decodeHex(input.toCharArray())); //line 209
} catch (Exception e) {
logger.warn("There was a problem when parsing LLRP Tags. "
+ "tag has not been added", e);
}
return retVal;
}

Added two lines in between lines 208 and 209:

input = input.trim();
if((input.toString().length()%2)!=0)
input = "0"+input;
retVal = new BigInteger(Hex.decodeHex(input.toCharArray())); //former line 209

I guess you'll use a better solution, but this way works for the app I did.

Too bad I can't export the edge server, but since I didn't add any dependencies I just exported the LLRP reader plugin and replaced the .jar file in the edge server's plugin folder. It works just fine.

Thanks again for your answer. Take care!

andres.contreras
Posts: 8
Joined: Fri Mar 25, 2011 10:05 am
Organization: Servicios de Automatizacion RFID C.A.

Re: Motorola XR400, not getting any tags

Post by andres.contreras » Thu Mar 31, 2011 11:34 am

By the way, the full values of tags are:

Example of tags that can be read:
2222--> Actually--> 000000000000000000002222.
30EF7434--> Actually--> 000000000000000030EF7434.
and so on.

Examples of tags that CAN'T be read:
22222--> Actually--> 000000000000000000022222.
301EF7434--> Actually--> 0000000000000000301EF7434.

As you see, the ones that can be read are the ones with an even number of significant figures. The ones with the odd number of significant figures throw the exception.

Best regards.

Matt
Posts: 362
Joined: Fri May 02, 2008 11:56 am
Organization: Pramari

Re: Motorola XR400, not getting any tags

Post by Matt » Thu Mar 31, 2011 12:56 pm

Hi andres,

Even better catch, I missed it the first time around that it was a problem with the even/odd in that hex library and not the leading zeroes (which we have had some trouble with before). I'll add that as a bug to fix before we release the next version.

Sorry again about the annoying build process - we are working on fixing that in a new version, so anyone can easily build and deploy the entire project if they want to.

-Matt

Nervin
Posts: 18
Joined: Tue Aug 03, 2010 3:46 pm

Re: Motorola XR400, not getting any tags

Post by Nervin » Sat Feb 18, 2012 12:40 pm

Hi Matt,
I encountered the same issue with the Impinj reader, was their a fix for Edge server 1.3 release or still using same as 1.2. Thank you

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