Wachendorff WDGA CANopen, Technical Manual, Page: 24 / 82

Technical Manual
WDGA with CANopen-Interface
5 - General information about CAN
© Wachendorff Automation GmbH & Co. KG 13 Rev.1.24
A CAN network can operate with baud rates up to 1 Mbit/s. Due to the necessary
synchronisation of the nodes, the maximum delay caused by the length of the cable
has to be limited. The limitation corresponds with the baudrate. There is a common
recommendation of the maximum cable length at several baud rates.
Baud rates Cable length
10 kBit/s 6,7 km
20 kBit/s 3,3 km
50 kBit/s 1,3 km
125 kBit/s 530 m
250 kBit/s 270 m
500 kBit/s 130 m
1 MBit/s <40 m
Table 5.1: CAN baud rates und recommended cable length limits
5.2 CANopen
CANopen is a specified higher protocol (layer 7 protocol) (Figure 5.3).
Figure 5.3: ISO-OSI-Modell
With CANopen it is possible to transfer larger amounts of data, emergency telegrams
and process data. CANopen describes how the communication is performed. That
means that parameters to configure a device are transmitted in a defined form (profile).
A CANopen profile defines objects representing the different functions of a device.
These objects form a table called object dictionary.
0
200
400
600
800
1000
40 150 270 530 1300 3300 6700
Baud
rate
[kbit
s/s
]
Cable length [m]