Error frames : which node sent the message
When error frames occur in a bus, 2 questions come up :
- Which node destroyed the message by sending an error frame ?
- Which node sent the message that was later destroyed ?
The first question is not easy to answer, because every node in a bus can be the sender of the error frame, it will look alike every time. This problem can only be found by measuring at different places on the bus and temporarily disconnect one node after the other.
To answer the second question, we have a fair chance to answer it with the CBT2.
By using the online trigger measurement you are able to show the last flawed message within the oscilloscope display. Therefore you should trigger to error frames only (deselect the other triggers on the left side).
Now start a single measurement, the tester stops at the next error frame. Da last message is now displayed in the oscilloscope display. You have a good chance that the error frame came after the arbitration, so you can read the ID of the node that sent the message. In the screenshot, it is ID 702 (the green marked area of the oscillogram is the ID).
