Invalid packets in Node Finder

Posted: 12 years ago Quote
What kind of checks are done to classify an item as an "Invalid Packet" in the Node Finder? Will a packet with an invalid CRC16 or CRC5 be classified as an invalid packet, and if so, will I be able to see the raw data of such packets? I haven't got the hardware yet (volcano-related shipping problem) so I've only used the software with the supplied sample files, and I'm not sure if those contain any invalid packets.
Posted: 12 years ago Quote
An invalid packet is a packet that contains an invalid PID. CRC errors are flagged as bad in the Details View. The raw data of invalid packets is displayed in the Payload view as well as in the Message View.

If you load one of the sample files and click on a SOF packet, you'll see (in the Message View) that it is positioned on an A5 data item. A5 is the PID for a SOF packet. The 1480A unit looks for the PID after an RxCmd is received with the RxActive bit set. If the PID is not valid, the tree node is considered 'invalid'.
Posted: 12 years ago Quote
I see, thanks for the explanation. I do think it would be useful if packets with invalid CRC were classified as "invalid packets", though. I can't think of a situation where you would be interested in packets that were invalid with respect to the PID, without also being interested in packets invalid because of an invalid CRC.
Posted: 12 years ago Quote
It would be too much overhead to calculate the CRC for all data packets received. We only need to check the PID byte to keep track of the number of each packet type in the Node Finder.