Explains vocabulary and abbreviations used in CAN technology
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Definitions:
See transmit error counter.
In CAN high-speed networks with bus line topology, both ends are terminated with resistors (120 0) in order to suppress reflections.
The thick cable is specified in the physical layer definitions of the DeviceNet specification. This cable is used for networks longer than 100 m.
The thin cable is specified in the physical layer definitions of the DeviceNet specification. This cable is used for drop lines and networks shorter than 100 m.
Standardized message in CANopen containing the time as a 6-byte value given in ms after midnight and days after 1st January 1984.
Atomic time unit in a CAN network.
Some CAN controllers provide the possibility of assigning time information to each received message. For TTCAN level 2 it is also required that the transmitting node captures the time and includes the time stamp in the data field of the very same frame.
Time-triggered messages are transmitted in pre-defined time slots. This requires a global time-synchronization and the avoidance of automatic retransmission of faulty messages. Time-triggered communication for CAN is standardized in ISO 11898-4 (TTCAN).
See type of services.
Physical connection structure of the network (e.g. line, ring, star, and tree topology).
See transmit PDO.
Local memory in the CAN controller, where the message to be transmitted is stored.
Internal event in the CAN controller to transmit a message.
In TTCAN level 2 it is required to capture the time when the SOF bit of the reference message has been transmitted.
CAN open object defining the scheduling of a CANopen communication object such as e.g. PDO.
CAN controller internal counter for transmission errors. The TEC value is readable in some controllers.
A process data object that is transmitted by a CANopen device.
A node from which a data or remote frame (only in Classical CAN) originates. This node remains transmitter until the bus is idle again or until the node loses arbitration.
Delay from the CAN FD controller's transmit flip-flop (FF) to its receive flip flop. When the CAN FD controller sends a bit, this bit appears at the CAN FD controller's receive pin after TD. TD includes the micro-controller internal delay, the transceiver delay and the delay on the ECU. This term is defined in ISO 11898-1. In CiA 601-1 the term transmitting node delay has the same meaning.
At bit-rates higher than 1 Mbit/s in the data phase of CAN FD frames the transmitting node has to compensate the TD when comparing its transmitted bits to the delayed received bits. TDC mechanism defines a secondary sample point SSP. When it is used, the transmitter ignores bit errors detected at the (first) sample point. The received bit value is compared at the SSP, with the (delayed) transmitted bit value. If a bit error is detected at the SSP, the transmitter reacts to this bit error at the subsequent following sample point. Bit error detection is disabled for those bits at the end of the data phase where the SSPs of the bits would be in the following arbitration phase. This term is defined in ISO 11898-1. In CiA 601-1 the term transmitting node delay compensation is used to avoid misinterpretations as the transceivers discussed there have a transmitter part.
See transmitter delay.
See transmitter delay compensation.
Network topology with a trunk line and branch lines. The not terminated branches may cause reflections, which shall not exceed a critical value.
This value includes the propagation segment as well as the Phase_Seg 1 of a bit time.
This value is the same as the Phase_Seg 2 of a bit time.
Standard CAN with extensions to support a global clock and scheduled transmission of messages in a system.
Higher-layer protocol defining time triggered communication in CAN-based networks. The CAN controllers have to be capable of switching-off automatic retransmission of faulty messages and may be able to capture a 16-bit timer value at SOF transmission in order to transmit the timer value in the very same message. It is standardized in ISO 11898-4.
As defined in CiA 602-2, the 3-bit TOC field of a C-PDU indicates whether it is a J1939 mapping C-PDU or a padding C-PDU.
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