ID trap

 Měření četnosti výskytů zpráv, jejich parametrů a změn dat na CAN sběrnici

The ID trap is particularly useful for two purposes. First, you can use it to read out the identifiers of messages present on the bus and count their frequency within set time interval. Second, it can help you to identify asynchronously generated message due to an event or status change.

Press Run to start the measuring; the data in the tree is refreshed based on selected time interval. Once a message is captured that is not present in the list, the identifier of that message is put in the list and the counter is set to one. Next time the message occurs, the counter is increased by one. After the specified time interval passed, all the counters are reset to zero. Messages not present in the just passed interval, i.e. with zero-value of the counter, however present on the bus in previous intervals, are displayed with a red spot. Messages with a non-zero counter value have a green spot. The blue spot stands for an identifier, that has been captured for the first time on the bus. Press the Stop button to stop measuring and evaluate the data. Press the Reset button to clear the message tree; the tree starts to create again next time the measuring starts.

1 Message with extended identifier 0-0. Already captured, however not present in last interval.
2 Messages with standard identifier. The message with blue spot is new – it has been added to the list in the just passed interval. The rest of the messages with green spots have already been captured in previous intervals.
3 The Counter represents the total number of messages with this ID in previous interval. The message with standard ID has been captured 15 times.
4 The RTR Counter represents, how many of them was a RTR type.
5 The Last represents time the message was last captured.
6 The Length subtree represents the number and the length of the messages. Length = the number of data bytes.
7 The message with length of 7 was captured 15 times within last second.
8 Data bytes subtree. DB0 changed the value in the last interval at least once (green spot). Last message contained data byte 0 with a value of 70.
9 DB1-DB6 didn’t change the value in the last interval (red spot). DB1-DB4 contained a 0 value in all of the messages. DB5 had a value of 135 and DB6 had a value of 140.