Incorrect tag code displayed in SG UI

@TvE I’m seeing an invalid code displayed for a CTT tag in the SG UI.

The tag is 78554C33 but is displayed as 78554c3358 with two additional digits at the end.

It’s actually being detected properly; it’s just the display that appears in error.

image

1 Like

The two extra digits are the CRC-8/SMBUS. Old receiver dongles didn’t receive them and/or print them, newer ones do, and older tags didn’t TX the CRC, something like that. (I can look up some of the specifics and some I don’t know.) It looks to me like you may have two 78554c33 test tags, one that does transmit the CRC and one that doesn’t?

Interesting. Those additional digits are not part of the id stored in the db. 78554C33 is the tag that exists in the db. 78554c3358 doesn’t exist as a registration. But the ID both displayed and recorded contains the two extra digits (just checked the raw data). I’m faintly recalling now some earlier conversation about truncating during processing those as they are aren’t part of the identifier in Motus… We’ll have to confirm that, but it may make most sense to exclude those digits at the SG level for consistency with the db, even if it’s being handled correctly at some stage of the processing.

1 Like

It would be good to get some backend processing info… The dongle reports either the 4-byte ID or the 4+1 byte ID+CRC. In the code this has always been written as-is into the files. There is quite a big difference in reliability (in the false positive sense) between getting just the ID vs. ID+CRC so this has to be carried through and into the data. I do not know where & how this is supposed to be flagged in the Motus data in the end. It’s quite possible that CTT made the change to having the CRC and the Motus back-end was never changed to reflect this or record which hits are with vs. without CRC.

The CRC validates the Tag ID, and assigns the Validated flag =1, if true, for both LifeTags and HybridTags. There is no CRC for PowerTags (currently). Any Life or HybridTag showing Validated = 1 is a positive ID with 99% certainty. The Tag ID is the first 8 chars.

1 Like

Yes the tag ID as recognized by Motus is just the first 8 characters, so the CRC must be dropped/truncated at some point during import given it’s being recorded in the data (it’s not just display, as I initially thought). The validated flag is retained in the detection data, so the CRC is still represented even the digits themselves are dropped.