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ISO1042-Q1: CAN Bus off

Malakondareddy B
Prodigy 155 points
Part Number: ISO1042-Q1
Other Parts Discussed in Thread: ISO1042

Tool/software:

Hi everyone,

I am using ISO1042Q in few of the boards  in my CAN architecture that contains 9 nodes (architecture will share you if required ). I getting BUS OFF the movement I send data from advantech board and no issues while receiving the data. However there is no issues  if I remove Power board and battery node from CAN Bus. 

The following nodes are battery ground:

1. Battery - unknown CAN transciever 

2. Power board 

3. Two motor controllers - unknown CAN transciever

Remaining are isolated grounds with ISO1042Q1 transciever 

Note: Bus off because of TX errors going 252 . I have not connected all CAN grounds and only used CANH and L lines.

Please suggest correct method to debug this issue 

Thanks in advance 

  • 0
    TI__Mastermind 28415 points

    Hello Malakondareddy B,

    Thank you for reaching out. Please see my comments below for starting the debug.

    1. Please make sure all the CAN BUS sides of the transceivers are connected to the same ground line. This will help limit the effects of ground shifts if any are happening due to the power and battery board. 
      1. The logic side of each node will be protected if each node isolated using ISO1042 and isolated power and grounds. 
    2. Please confirm two, 120-ohm termination resistors are placed at the farthest nodes of the CAN network for best performance. 
    3. Please share the architecture and schematic if possible. 

    Best,
    Andrew 

  • 0 in reply to Andrew J
    Prodigy 155 points

    Thanks for reply,

    The first question: currently I have not connected CAN grounds and only take CANH and CANL lines, since I thought CAN will work without ground because of differential

    2nd question: Yes it is properly terminated and got 60 ohm in multimeter

    3nd question: shared through mail. Please check and let me know.

    Could you please accept my friend request so that I can clearly explain my problem?

    Thanks 

  • 0 in reply to Malakondareddy B
    TI__Mastermind 28415 points

    Hello, 

    CAN Bus will work without a ground line since it is differential, however, typically all CAN nodes are grounded to the Cable ground. A common ground for ground nodes helps limit the effects of ground shifts. 

    I have sent the friend request. 

    Best,
    Andrew