|CANopen in a higher
layer protocol based on CAN (Controller Area Network), which enables the communication
between devices of different manufacturers and guarantees an interchangeability of
The profile family CANopen defines a standardised application for distributed industrial
automation systems based on CAN. CANopen was developed within the CAN-in-Automation (CiA)
international users' and manufacturers' group and is now standardized as CENELEC EN
50325-4. Soon after its release, CANopen has found a broad acceptance, especially in
Europe where it can be considered the leading standard for CAN based industrial and
embedded system solutions.
The most important device types such as digital and analog I/O modules, drives,
controllers, programmable controls or encoders, are described by so called "Device
Profiles". In these device profiles functionality, parameters and the access to
process data of standard devices of the corresponding types are specified. Based on these
standardized profiles devices of different manufacturers can be accessed via the bus in
exactly the same manner. Vendor independence is thus achieved to a large extent as devices
of different manufacturers are interoperable and exchangeable.
By now it is used in many various fields, such as medical equipment, off-road vehicles,
maritime electronics, public transportation, building automation, etc.
Physical structure of a CANopen network
Two basic conditions must be fulfilled in order that a CANopen network can function
from a physical point of view:
- All nodes must be configured to the same bit rate and
- No node-ID may exist twice.
Unfortunately there are no mechanisms with which these conditions can be automatically
ensured, so that the system integrator must check the bit rate and node-ID of every single
network node when wiring a network and adjust if necessary. Normally the node-ID is
configured directly on the device via DIP-switches or hexadecimal rotary switches.
Alternative solutions require setting of these parameters via two reserved CAN identifiers
by software with the aid of the so-called "LSS-service" (layer setting service).
Here the device to be configured is to be connected 1:1 with a configuration device.
As generally required for CAN networks, both ends of the network must be terminated with a
120-Ohm terminal resistance between wire 2 (CAN_L) and wire 7 (CAN_H). In addition, the
maximum permissible branch lengths for connection of the individual network nodes are to
The recommended permissible bit rates for a CANopen-network are given in DS-301: 10 kbps,
20 kbps, 50 kbps, 125 kbps, 250 kbps, 500 kbps, 800 kbps and 1000 kbps. In DS-301 a
recommendation for the configuration of the bit timing is also given.
CANopen Tools available from Nohau UK
our partner IXXAT Automotion Gmbh we offer the following tool to assist engineers
developing with CANopen:
Configuration Studio >>>
The CANopen Configuration Studio is a convenient, powerful tool for the
design and configuration of CANopen devices and networks. Highlights of
the tool are its modularity and extendibility, and its concise
representation of process data and network topology.
CANopen EDS Editor
The CANopen EDS Editor enables convenient processing of EDS files. Its
simple user interface offers device manufacturers and system
integrators all the functions required to create or maintain
existing EDS files.
CANopen Device Manager >>>
The CANopen Device Manager is a small, but extremely versatile tool
targeted at all tasks requiring direct CANopen device access. These
include device development and test, service and diagnostics tasks, as
well as device configuration. CANopen Device Manager fully supports
SDO, PDO and LSS master services as well as the download of
configuration data and firmware update according to CiA
302. CANopen Device Manager particularly stands out with its
flexible plug-in interface allowing the user to extend the basic
functionality with optional add-on modules including a powerful
CANbus Analyser with CANopen Module >>>
The CANopen module option for canAnalyser interprets all received CAN
messages in accordance with the CANopen specifications DS-301, DS-305,
DS-401, DS-402, DS-405 and DS-406. The messages are recognised as SDOs,
PDOs (also multiplexed), NMT, Emergency, Sync and Timestamp objects and
interpreted accordingly. In addition, the Error Control, LSS and Flying
Master protocols are interpreted. These are displayed in plaintext,
colour-coded according to the message type. Interpretation of the data
received is based on a configuration set. This either assigns an
EDS/DCF file to each of the 127 possible network nodes or defines its
device profile. The configuration set can be loaded, edited and saved.
The profiles used for interpretation are integrated via external text
files, whereby the CANopen module can be very easily extended by new
profiles. Due to its flexible structure, the CANopen module can thus be
used universally in all CANopen systems.