Problem with CAN-CR200

Completed

Sebastian Tryk

• March 06, 2025 12:05

Problem description: we have a problem with errors appearing on the CAN bus. In the vehicle (tram) we have a CAN bus, the total length of which is 225 m (25 nodes). The transmission speed is 250 kb/s. After installing a CAN repeater from another company, approximately halfway along the bus, the errors disappear (which may indicate a problem with the length of the bus itself). After switching on the CAN repeater IXXAT 1.01.0067.44010 in the same place, the situation worsens (colleagues mentioned that this device does not pass all CAN frames). The CAN3 is set to ON, Lock Time is set to 300.

What else could be changed in the repeater configuration?

0

• Official comment

  

  Andreas Stobe

  • March 13, 2025 09:09

  Dear Sebastian,
  
  The maximal CAN bus length for the CAN baud rate 250kBd is about 280m.
  The CAN-CR200 works real-time transparent bit-wise and
  can be used for the galvanic isolation, signal improvement, splitting of the capacitive load,
  making possible star topology but it reduces the maximal CAN bus length by 40meters.
  
  

                111m           (40m)           114m         
  [R]-------+---...---+---[R]CAN-CR200[R]---+---...---+[R]  
  Node1   Node2     Node12                 Node13   Node25  

  So the CAN bus length is almost on limit (111m + 40m + 114m = 265m).
  
  If there are CAN-Error-Frames even with the 500ns lock time, then
  I would recommend the use of a CANbridge NT 200 instead of the CAN-CR200.
  The CANbridge NT 200 works message-wise and extends (doubles) the maximal CAN bus length.
  
  Best regards
  Andreas

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