Knowledgebase: Terminology
Posted by Squarell Technology on 09 December 2013 10:18 AM

In electronics, electrical termination is the practice of ending a transmission line. ForCANbus,both ends of the pair of signal wires(CAN high and CAN low)must be terminated. This is because communication flows both ways on the CANbus. The termination resistors on a cable should match the nominal impedance of the cable.  This is intended to prevent signals from reflecting off the end of the transmission line. Reflections at the ends of unterminated transmission lines cause distortion which can produce ambiguous digital signal levels and mis-operation of digital systems. ISO 11898 requires a cable with a nominal impedance of 120Ω. If multiple devices are placed along the cable, only the devices on the ends of the cable need termination resistors.

CANbus Termination

Terminate the CANbus always with 2 terminators.

All FLEX cables are equipped with 2 removable terminators on CANbus 1.

  • Remove one terminator if the CANbus already is equipped with one terminator.
  • Remove both cable terminators when the Squarell device becomes part of an existing (terminated) CANbus system.