This article describes the difference between a High-Speed- and a Low-Speed-CAN.
CAN Interface board, CANbridge, CAN-Repeater
What is the difference between High-Speed-CAN and Low-Speed-CAN?
The High-Speed CAN is the "classic" CAN bus (according to ISO 11898-2), used in many (industrial) applications. The bit rates, defined by the "CAN in Automation" user organization are ranging from 10 kbit/s up to 1 Mbit/s. CAN signals are transmitted differentially. Using High-Speed CAN, the differential voltage for dominant bits is 2 V, for recessive bits 0 V.
A: The dominant level of the CAN-High wire is 3.5 V.
B: The recessive level of CAN-High and CAN-Low wires is 2.5 V.
C: The dominant level of the CAN-low wire is 1.5 V.
Low-Speed CAN, or Fault-Tolerant CAN (according to ISO 11898-3), is designed for improved durability. The recessive level of the differential signal is at -5 V, the dominant level is 2.2 V. If one of the two data lines is damaged, there is an automatic switchover to single-wire mode. This allows the system to be operated. The bit rates ranging from 40-125 kbit/s.
A: The dominant level of the CAN-High wire is 3.6 V.
B: The recessive level of the CAN-High wire is 0 V, of the CAN-Low wire 5 V.
C: The dominant level of the CAN-Low wire is 1.4 V.