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CANopen Bus | 07 Nov 2013 | |

CANopen Bus



CANopen is a communications protocol based on CAN which is used mainly in the automation engineering and to the networking within a complex equipment. Since 1995 it is maintained by the organization "CAN in Automation" (CiA) and is standardized as a European norm EN 50325-4.

Several basic services are defined in CANopen:

  • Request: Request of a CANopen service by the application
  • Indication: Report to the application that a result or a piece of certain news is available
  • Response: Answer of the application to an Indication
  • Confirmation: Confirmation to the application, that a CANopen service was executed

Also further communication concepts like the Producer Consumer concept are used in CANopen besides these client server services.

Communication objects

Communication objects can be subdivided as follows in

  • Service data objects (SDO) for parametrizing of object list entries. Service data objects provide a service to the access to the object list. Every CANopen device needs at least a SDO server which receives and works on SDO requirements of another equipment.
  • Process data objects (PDO) for the transport of real time data. Provides a fast possibility for the transport of process data. The contents of the using data are defined by PDO Mapping entries. These are objects in the object dictionary which fix like an assignment table which data are transmitted with a PDO. These data are contents of other objects of the object dictionary. The transmission of PDOs can be carried out cyclically, event orientated, requested or synchronizedly.
  • Network management objects (NMT) for the control of the condition machine of the CANopen device and for the supervision of the nodes,
  • further objects like synchronization object, time stamps and fault news.

Object Dictionary

All communication objects and all user objects are summarized in the object dictionary.

Index area Use
0000 unused
0001-009F Data types (special case)
00A0-0FFF reserved
1000-1FFF Communication profile
2000-5FFF manufacturer specific area
6000-9FFF up to 8 standardized equipment profiles
A000-AFFF Prozess copies of IEC61131 equipment
B000-BFFF Prozess copies of CANopen gateways to CiA 302-7
C000-FFFF reserved

For every communication object a clear COB ID (Communication Object Identifier) exists in the network.

CAN Objects

Device Profiles

For a number of device classes CANopen device profiles were defined:

Standard Device Class
CiA 401 IO modules
CiA 402 electrical drives
CiA 404 Sensors and controllers
CiA 405 Programmable devices (SPS) to IEC 61131-3
CiA 406 sensors
CiA 408 hydraulic drives

Application Profiles

In the application profiles the function of an application is described.

Electronic Datasheets

For the use of CANopen devices, electronic data sheets, so-called EDS files, are necessary. Configuration tools can read EDS files and communicate with the respective device and if necessary parametrize it.
EDS files for Kollmorgen servo amplifiers can be found in section Others / Archives on page ((Fieldbus Support Archiv)).

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