CANopen is a higher
layer protocol based on CAN (Controller Area Network), which enables the communication
between devices of different manufacturers and guarantees an interchangeability of
devices.
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
be observed.
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. |
With
our partner IXXAT Automotion Gmbh we offer the following software to assist engineers
developing with CANopen:
- CANopen Protocol Software
>>>
The CANopen Protocol Software includes all the necessary functions to
implement slave or simple master devices according to the CANopen
specification CiA 301. Support for LSS services according to CiA 305 is
included as standard.
- CANopen Manager
Software >>>
The CANopen Manager Software is a very powerful software package that
is optimally tailored at the implementation of complex CANopen manager
devices. In particular, the software package is suited for the
implementation of CANopen PLC devices and is based on the
specifications CiA 301, CiA 302 and CiA 405.
- CANopenRT
(Real-Time) Software >>>
The CANopenRT Software is an optimised version of the CANopen Protocol
Software featuring enhanced interfaces which permit a highly efficient
integration with either real-time or mainstream operating systems. The
software is particularly well-suited for multi-threaded
applications requiring CANopen connectivity.
- CANopen Maritime Software
>>>
The CANopen Maritime Software implements the CANopen framework for
maritime electronics, CiA 307, and is specially designed for the
increased safety standards required by maritime automation. It offers a
single-point-of-failure tolerance due to redundant communication and
support of the flying master concept.
- CANopen Master API
>>>
The CANopen Master API is a software package that allows easy
development of CANopen master applications such as control, service and
test programs under Windows. The CANopen Master API
is particularly well suited for applications that do not require
flexible configuration over the CANopen network.
- CANopen Manager API
>>>
The CANopen Manager API is a powerful and flexible software solution
that - in combination with a iPC-I XC16/PCI CAN interface - allows the
user to implement generic CANopen control applications. It can also be
integrated with IEC 61131-3 run-time environments on Microsoft Windows
based platforms. It is based on the CANopen Manager Software, and thus
fully supports the standardised CANopen boot-up procedure. The CANopen
Manager API conforms to the specifications CiA 301, CiA 302, and CiA
405.
|
