CAN Bus freezes when PC cable connected

[cmcraeslo]

Hello,

this is my first post to this forum. I'm not really sure if this is correct category, so I will post it here and would kindly ask the moderator to move this message in appropriate category if this one is not ok.

I have a custom made ECU that reads the data from MoTeC M800 via CAN BUS. Everything works ok, until I connect the laptop to the M800. Then, suddenly, CAN "freezes" and can no longer read the channels. As soon as disconnect the cable, everything works as it should. PC to M800 connection works ok.

Is there any way around this? Hopefully there's some setting available in the M800 that I can check ..

Thank you,

Marko

[mstech]

This sounds like a CANBus baud rate issue, check that they are all running at the same speeds, including ECU Manager. There may also be a CAN addressing issue, but I believe that it is most likely to be a baud rate issue.

[cmcraeslo]

hello. thanks for replying.

Im not sure i understand correctly.. how can this be a rate issue if i'm reading can at 1 mhz all the time. does the m800 switch to 500k when connected to the pc? also.. i tried reading with can sniffer and communication stops suddenly. im not 100% sure but i think i tried many different rates with the sniffer and i believe there was only some "pinging" once per second on 500k, something like connection attempts.. without any ecu channels.

m

[Mazi]

CAN_H and CAN_L swapped?

[AlanB]

Hello Marko

This is likely to be related to the CAN bus wiring. You can find details on how to wire the bus correctly via the help in ECU Manager.

Go to the 'Help' menu
Expand 'Wiring'
Click on 'CAN Wiring - Multiple Device'

The key points are presence of terminating resistors, wire twisting and spur length. Also, check that the CAN Hi and CAN Lo wires are the correct way around in the UTC connector (as previously mentioned).

[David Ferguson]

You would hope they figured this out sometime in the last 18 months. This thread is from Jan 2015