CAN dictionary

Explains vocabulary and abbreviations used in CAN technology

Alphabetic selection:


object dictionary

The object dictionary is the heart of any CANopen device. It enables access to all data types used in the device, to the communication parameters, as well as to the process data and configuration parameters addressable using a 16-bit index and an 8-bit sub-index.


See overload frame

open system interconnection (OSI) reference model

Layered communication model defining seven layers: physical (1), data link, network, transport, session, presentation, and application (7) layer. In CAN-based networks normally just physical, data link, and application layer are implemented.

operational state

Part of the CANopen NMT slave state machine. In the NMT operational state all CANopen communication services are available.


Set of specifications for communication (COM), network management (NM), real-time operating system (OS), and implementation language (OIL). OSEK/VDX is partly implemented in passenger cars.

OSI reference model

See open system reference model.

outer priority inversion

If a node wants to transmit two high­ prior CAN messages and is not able to send the second message directly after the intermission field, it may happen that a lower-prior message is transmitted by another node in between. This is called outer priority inversion.

overload condition

Situations when the CAN controller transmits an overload frame: e.g. dominant value in the first two inter-frame space bits, dominant value in the last bit of EOF, bit failure in last bit of error or overload delimiter.

overload delimiter

Last segment in overload frames made up of 8 recessive bits.

overload flag

First segment in overload frames made up of 6 dominant bits. A second overload flag transmitted by another node may overlap the first overload flag.

overload frame (OF)

Frame to indicate an overload condition. It is made up of the overload flag and the overload delimiter. The overload flag corresponds to that of the active error flag. The overload delimiter is the same as the error delimiter.

Source CANdictionary (2016) - CiA CAN in Automation -