CANopen lower layers

CANopen data link layer

CANopen is based on the CAN data link layer as standardized in ISO 11898-1. Although most addressing schemata are based on the base frame format (11-bit CAN identifier), CANopen supports the extended frame format (29-bit CAN identifier) as well. The CANopen CC specification CiA 301 is based on CAN CC. CANopen FD, specified in CiA 1301, is based on CAN FD.

CANopen CC bit timing

The table below illustrates the CANopen CC bit timing, the resulting maximum network length, and the maximum unterminated cable drop lengths. At least, all CANopen CC devices support one of the defined bit rates. Optionally, a CANopen CC device may support further bit rates. The location of the sample point shall be as close as possible to 87,5 % of the bit time.

CANopen CC bit timing table

Bit rate Bus length Max. stub length Accumulated stub length 1 Mbit/s 25 m 1,5 m 7,5 m 800 kbit/s 50 m 2,5 m 12,5 m 500 kbit/s 100 m 5,5 m 27,5 m 250 kbit/s 250 m 11 m 55 m 125 kbit/s 500 m 22 m 110 m 50 kbit/s 1000 m 55 m 275 m 20 kbit/s 2500 m 137,5 m 687,5 m 10 kbit/s 5000 m 275 m 1375 m

CANopen physical layer

CANopen assumes a physical layer according to ISO 11898-2. The pinning for various "CANopen connectors" is provided in CiA 106. Environmental requirements to the intended application field may demand deviations from ISO 11898-2. Therefore, CANopen is open to other physical layer options. In case other physical layer options are used, the resulting CANopen device is not interoperable in most CANopen applications.