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Hilscher Gesellschaft für Systemautomation mbH
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65795 Hattersheim
Germany

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CANopen

History
Developed	1985 Layer 1, 2 Bosch AG Layer 7 CiA
Norm	ISO 11898
User association	CAN in Automation www.can-cia.org
Market	Europe

The CAN protocol was originally developed by Robert BOSCH GmbH for the European automobile industry in order to replace expensive wiring in cars with a cheaper network cable. For an event, the CAN protocol has fast reaction and a high degree of reliability such as is necessary, for example, for controlling ABS brakes and airbags. From this there has developed a communication standard for application in automation technology.

Controller Area Network is generally a line network. Every participant hears all messages of the others and can send messages at any time. Simultaneous bus accesses are recognized and released (CSMA/CA) through arbitration within the 11- Bit message header (Identifier). The header thus defines the priority of the message, whereby each can contain up to 8 Bytes of user data.

System data
Max. devices	127
Max. baud rate	1 MBaud
Max. extension	5000 m @10 kBaud 40 m @1 MBaud
Bus access	CSMA/CA
Communication	Master / Slave
Max. I/O data	4064 bytes input 4064 bytes output
I/O connection	cyclic synchronous remote requested
Message channel	SDO practical unlimited data amount

The transmission rates in the CANopen range from 10 kBaud up to 1 MBaud. The CANopen specification CiA DS-301 defines special functions for 2048 possible CAN messages. The scheme of issuing is designed according to the Master/Slave principle and permits a point-to-point linking between one Master and 127 node participants. Also Broadcast transmission types such as synchronized transmission of data or Slave-to-Slave communications are supported.

Due to differing requirements, there are two types of data. PDOs (Process-Data-Objects) are real-time data that can be transmitted quickly with high-priority identifiers. Thus, only a maximum of 8 Bytes per message can be sent. The data of a message can be configured over the network. One talks of so-called PDO Mapping. PDOs can be transmitted in an event-orientated, remote request or synchronized manner.

Data of the CANopen-Slave Implementation

Profile	CiA DS-301
Min. Boot up	yes
Emergency message	passed by the application
Heartbeat	yes
PDO	on change
PDO mapping	yes
Process image	max. 510 bytes

Data of the CANopen-Master Implementation

CANopen nodes	max.127
Min./Max Boot up	Bootup sequence per parameterization
Emergency	Buffer for up to 64 Messages per node
Life Guarding	Guard-Time and Life time factor adjustable
PDO	unlimited number of PDOs per node
Transfer	cyclic on change sychronous remote requested
SDO	Up- and Download service 246 bytes per message
Process image	max. 7 KByte

Performance CANopen Implementation

@ CIF 50-COM, CIF 30-COS, 1 MBaud, cyclic

Bus cycle time	4,58 ms 8,52 ms 12,21 ms	@16 Slaves with 2 bytes @16 Slaves with 8 bytes @16 Slaves with 16 bytes
Reaction time	1,16-1,48 ms	@1 Slave with 1 byte