Re: can demo
- From: Paul Keinanen <keinanen@xxxxxx>
- Date: Sat, 12 Jul 2008 17:55:16 +0300
On Sat, 12 Jul 2008 16:12:53 +0200, Heinz-Jürgen Oertel
<hj.oertel@xxxxxxxxxxx> wrote:
I think that it can be that the transmission in his case does not finish.
One reason, the CAN transceiver gets no acknowledge. A typical failure of
novices. CAN is in this regard very different from sending a byte via a
UART.
This might well be the case, since the OP did not say anything about
what other devices there are on the bus.
If the development kit is the only device on the CAN bus, the
transmitter tries over and over again to send the same message, until
an other device is connected to the bus, which acknowledges the
transmission.
This CANbus feature can be quite nasty if you are sending commands
over CANbus and the bus is intermittent for some reason. When the bus
is finally working again, a very outdated command might get through,
causing various kinds of hazards. In such cases, some higher level
protocol is required, e.g heartbeat messages or time tagged commands
etc. Clearing the transmission queue and reseting the CAN controller
chip if it appears to be stuck also reduces the risk related to
delayed commands.
Paul
.
- References:
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- Re: can demo
- From: Paul Keinanen
- Re: can demo
- From: Heinz-Jürgen Oertel
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