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3 General information
3.1 CANopen technology
The CANopen communication profile is based on the CAN Application Layer (CAL)
specification of the CiA organisation� CANopen is considered as a robust fieldbus
with highly flexible configuration options� It is used in many various applications
which are based on different application profiles� CANopen comprises a concept to
configure and communicate real-time data using synchronous and asynchronous
messages� Four message types (objects) are distinguished�
1� Administration messages (layer management, network management and
identifier distribution)
2� Service Data Objects (SDO)
3� Process Data Objects (PDO)
4� Predefined Objects (synchronisation, time stamp, emergency)
For further information please refer to the CiA-CAN specification (CiA 406 -
encoders, CiA 301 - CANopen)�
3.1.1 Supported operating modes
Encoders with CANopen interface support the following operating modes:
● RTR (request)
The position value is only given to the bus on request�
● EVENT time
The position value is given to the bus cyclically (interval can be set)�
● Cyclical-synchronous
When the sync telegram has been received by the host, the absolute encoder
transmits the current process value� A sync counter can be programmed so that
the encoder does not send before a defined number of sync telegrams�
In addition other functions can be configured (direction of rotation, resolution etc�)�
3.2 References
http://www�can-cia�org
CAN Application Layer, DS 201 ...207
LSS profile
CAL-based communication profile,
Device profile for encoders
CAN specification version 2�0 A
CANary CAN controller
CANopen encoder
CiA
DS305 CiA
DS 301 CiA
DS 406 CiA
Robert Bosch GmbH
Atmel
UK
5
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