Helmholz 700-672-PNC01 - 5 CAN Bus; Wiring a CAN Bus; CAN Bus Plug

PN/CAN Gateway, PROFINET/CANopen Slave | Version 2 | 1/26/2021 15
5 CAN bus
CAN bus (Control Area Network) is an international open fieldbus standard for building,
manufacturing, and process automation applications. CAN bus communications are defined in
standard ISO 11898-2.
5.1 Wiring a CAN Bus
A CAN bus cable requires at least three wires: CAN high, CAN low, and CAN ground. Only linear bus
topologies are allowed, A terminating resistor of 120 ohms must be connected between CAN high and
CAN low at both ends of the CAN bus cable. The PN/CAN Gateway has no installed bus terminating
resistor.
The maximum cable lengths will depend mainly on the bit rate being used.
Bit rate Bus length Bit time
1 Mbps
30 m 1 µs
800 kbps
50 m
1.25 µs
500 kbps
100 m
2 µs
250 kbps
250 m
4 µs
125 kbps
500 m
8 µs
50 kbps
1500 m 20 µs
The cable lengths specified above should only be used as reference values. The maximum cable length
will also depend on the number of connected participants, on the use and the number of repeaters
and on the cable type.
5.2 CAN bus plug
Helmholz offers a comprehensive range of CAN bus connectors that can be used with the PN/CAN
Gateway. All Helmholz CAN bus connectors come with a terminating resistor that can be switched on
and off.