Electronic – CAN bus stuff error causes due to physical layer

can

I'm trying to diagnose the significant amount of bus "stuff errors" on my CAN network. Network is new and has not ran without these errors. Topology is as shown below.

enter image description here

  • 18 Devices on CAN bus. 9 on each side, joined at din rail terminals.

  • Cable on the outside of dotted lines are this twisted pair
    cable    .

  • Cable on inside of dotted lines to din rail terminals is
    this shielded twisted pair cable.

  • Dotted lines represent deutsch connector.

  • Bus length is roughly 20m – 25m

  • Bit rate is 500kbits/s

My question relates to the physical layer because I can be fairly sure software is working correctly.

Can any of the following things cause stuff errors on the bus?

  • Two different cable types
  • Sections of non shielded cable
  • A bad high or low connection to a device

Here is a picture of the CAN signals on a scope.

enter image description here

Here is an example of CAN traffic showing errors:

   355)      4916.3  Rx         0520  5  A6 0C 64 00 06 
   356)      4919.6  Rx         0523  8  05 00 00 00 41 00 00 00 
   357)      4919.8  Rx         0526  6  C0 01 08 00 08 01 
   358)      4920.3  Rx         0525  6  A8 73 AC 0D D0 02 
   359)      4920.5  Rx         0525  6  34 73 AC 0D D0 02 
   360)      4920.7  Rx         0523  8  B4 00 00 00 40 00 00 00 
   361)      4920.8  Error      0004  4  01 0A 01 00
   362)      4920.9  Error      0004  4  01 0A 02 00
   363)      4920.9  Error      0004  4  01 0A 03 00
   364)      4921.0  Error      0004  4  01 0A 04 00
   365)      4921.2  Error      0004  4  01 0A 05 00
   366)      4921.2  Error      0004  4  01 0A 06 00
   367)      4921.5  Rx         0523  8  10 00 00 00 41 00 00 00 
   368)      4921.7  Rx         0523  8  62 00 00 00 50 00 00 00 
   369)      4922.0  Rx         0523  8  1C 00 00 00 50 00 00 00 
   370)      4922.0  Error      0004  4  01 0A 04 00
   371)      4922.1  Error      0004  4  01 0A 05 00
   372)      4922.2  Error      0004  4  01 0A 06 00
   373)      4922.3  Error      0004  4  01 0A 07 00
   374)      4922.4  Error      0004  4  01 0A 08 00
   375)      4922.4  Error      0004  4  01 0A 09 00
   376)      4922.6  Error      0004  4  01 0A 0A 00
   377)      4922.6  Error      0004  4  01 0A 0B 00
   378)      4922.7  Error      0004  4  01 0A 0C 00
   379)      4922.8  Error      0004  4  01 0A 0D 00
   380)      4922.9  Error      0004  4  01 0A 0E 00
   381)      4923.0  Error      0004  4  01 0A 0F 00
   382)      4923.1  Error      0004  4  01 0A 10 00
   383)      4923.2  Error      0004  4  01 0A 11 00
   384)      4923.3  Error      0004  4  01 0A 12 00
   385)      4923.3  Error      0004  4  01 0A 13 00
   386)      4923.4  Error      0004  4  01 0A 14 00
   387)      4923.7  Rx         0523  8  9C 00 00 00 4F 00 00 00 
   388)      4923.7  Error      0004  4  01 0A 14 00
   389)      4923.8  Error      0004  4  01 0A 15 00
   390)      4924.1  Rx         0523  8  CC 00 00 00 41 00 00 00 
   391)      4924.1  Error      0004  4  01 0A 15 00
   392)      4924.2  Error      0004  4  01 0A 16 00
   393)      4924.3  Error      0004  4  01 0A 17 00
   394)      4924.4  Error      0004  4  01 0A 18 00
   395)      4924.4  Error      0004  4  01 0A 19 00
   396)      4924.6  Error      0004  4  01 0A 1A 00
   397)      4924.7  Error      0004  4  01 0A 1B 00
   398)      4924.8  Rx         0525  6  86 73 AC 0D D0 02 
   399)      4925.0  Rx         0525  6  28 73 AC 0D D0 02 
   400)      4925.1  Error      0004  4  01 0A 1A 00
   401)      4925.2  Error      0004  4  01 0A 1B 00
   402)      4925.4  Rx         0525  6  4B 73 AC 0D D0 02

Best Answer

I'm only going to answer one of your questions. Can two different cable types cause errors. Yes, if the cables have different characteristic impedances, signals may be reflected at the cable interfaces. I have no idea whether that is an issue in your case, however.

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