Hello again,
Myself and my team are continuing to work on a project with the M6E at its heart. We struggling with two problems at the moment…
PROBLEM 1. The tags – we’ve purchased a whole cupboard-ful of SparkFun’s sticky RFID tags – are a bit capricious as to when they’re being read. We’re trying to use the tags to scan boxes. Each box has a tag affixed to it. We’re scanning the boxes one by one, lowering the external antenna to within about a yard of the tag. In a run of eight boxes, we almost always get one or two tags which aren’t read. Swapping tags doesn’t really help; another tag, which was being read perfectly well before, will then switch to being the uncooperative one. The boxes are almost 100% wood, and we’ve set the reader to the full 27.00 dBi. Do you know of any easy tricks to sort this out? Or could you recommend any super-duper reliable tags? (We’ve tried a few other brands, and they all seem slightly worse than SparkFun’s.)
PROBLEM 2. We’re still struggling with the old “Module failed to respond” error cropping up uncomfortably often. Inspecting nano.msg[0] gives an error code of 2, “Corrupt response”, or occasionally 3, “Wrong opcode”. A team member suggested it might be caused by a bad value getting stuck in a cache somewhere. Does that sound right? Could you suggest another explanation?
Thanks,
Tom
Hi again Tom,
For Problem 1, it sounds like a minor interference issue. Does removing the tag from the box allow you to scan the tag again or does it not matter whether it is attached to the box or not? Are they all in the same position on the boxes being scanned and are the any other factors that would cause interference? How are you aligning the tag with the external antenna and, assuming you are using the [UHF Antenn we carry, does adjusting the orientation of the tag or reader help at all? Keep in mind the antenna we carry has a linear-vertical polarization so ideally, you want to have the tag aligned with the antenna in a vertical position similar to the photo in the [Range Test Example from the Hookup Guide.
As for a recommended tag, I have only tested these with the tags SparkFun carries and have not noticed this kind of issue as far as I can recall. You could search for larger EPCglobal Gen 2 (ISO 18000-6C) UHF Tags than the ones we carry as that should help with the read range. The manufacturer of the M6E Nano module, Jadak/Novanta, may have recommended tags that perform better than the ones we carry.
Now, for Problem 2, this is a bit trickier to troubleshoot since we have covered most of the common causes for this already in your previous posts. Is the issue only showing up on one Simultaneous RFID Reader or does it crop up on multiple readers? If it is just one, the best course here would probably be to just have the board sent back to SparkFun for testing to try and replicate your results. If you are getting it with multiple readers, can you refresh my memory here and provide a detailed description of what you have the Simultaneous RFID Reader connected to (eg. type of Arduino or other microcontroller), how you are powering it including specifications of the power supply and also a few new photos of your board(s) and the setup you have them in?](https://learn.sparkfun.com/tutorials/simultaneous-rfid-tag-reader-hookup-guide/example-10---range-test)](https://www.sparkfun.com/products/14131)