CAN Bus Off

Question

Hai ,can any one help us in diagnosing the following issues1,What will happen when we induce CAN Bus Off in a network of 4 nodes?(Only specific node will goes to bus off with respect to RTR bitmessage we blocked or all the nodes on the network goes to Bus Offstate.if so why?)2,When we will get Fault notification frame from ECU if it enters in toBus Off (Before entering in to Bus off or after re-initialization ofECU(i.e after recovery)?)3,How  can we calculate the Bus Off recovery time? (Is it the timedifference between the last valid frame transmitted before inducing BusOff (error frames) and after recovery from Bus Off).4,Is the recovery time depends on the time we are blocking RTR bit orECU will recovery automatically after specified time though we block .5,can we block ack or RTR for specified time using CAN Stress tool, ifso how?Thanking you allfrom raj

Hans-Bernhard Broeker · Accepted Answer

Impossible to tell, if you don't tell *how* you induce it.  Generally,bus-off is not a state you can induce "in a network", but one that aeach CAN node can be in on its own --- or not.Read the word: "bus off".  Do you seriously expect a node in such astate to go _on_ the bus and send something?You can't, because there's no such thing.  Recovery from Bus Off isspecified in terms of successfully received bits, not time.The CAN spec is really quite explicit about all such things.  Read it.Then read it again, and understand it.-- Hans-Bernhard Broeker (Even if all the snow were burnt, ashes would remain.

Hans-Bernhard Broeker · Answer

Hmmm... getting a CAN node into bus-off state shouldn't be hard. Just put it on a bus all of its own, or one where all other nodes have completely different timing, so it will never receive an ACK, or be flooded with error frames every time it tries to send.

banh · Answer

putting a node on its own and keep on transmitting will not lead itself to bus-off!!

this is because the CAN spec says that under this condition (only 1 node on the bus keeping on transmitting), the node should not go to bus-off state.

And, for this case, I already tried, and never got to bus-off successfully.

however, with different nodes with different timing, i'm not sure whether this will work..

Heinz-Jürgen Oertel · Answer

A short cut of CAN_H and CAN_L definitely forces a _transmitting_ controllerto Bus-Off Heinz

raj · Answer

How Bus off is handled at hardware level and software leveldifferently?

Grant Edwards · Answer

Yes.-- Grant Edwards                   grante             Yow!  I'm ZIPPY the PINHEAD                                  at               and I'm totally committed                                           to the festive mode.

CAN Bus Off

Join the Discussion

Didn't find your answer?