Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.
The Controller Area Network (CAN) specification defines the Data Link Layer, ISO 11898 defines the Physical Layer.
The CAN bus [CANbus] is a Balanced (differential) 2-wire interface running over either a Shielded Twisted Pair (STP), Un-shielded Twisted Pair (UTP), or Ribbon cable. Each node uses a Male 9-pin D connector. The Bit Encoding used is: Non Return to Zero (NRZ) encoding (with bit-stuffing) for data communication on a differential two wire bus. The use of NRZ encoding ensures compact messages with a minimum number of transitions and high resilience to external disturbance.
CANbus interface Circuit
CAN Bus Electrical Interface Circuit
A number of different data rates are defined, with 1Mbps (Bits per second) being the top end, and 10kbps the minimum rate. All modules must support 20kbps. Cable length depends on the data rate used. Normally all the devices in a system transfer uniform and fixed bit-rates. The maximum line length is 1Km, 40 meters at 1Mbps. Termination resistors are used at each end of the cable. The worst-case transmission time of an 8-byte frame with an 11-bit identifier is 134 bit times (that's 134 microseconds at the maximum baud rate of 1Mbits/sec).
CANBus Protocol Frame
The CAN Bus interface uses an asynchronous transmission scheme controlled by start and stop bits at the beginning and end of each character. This interface is used, employing serial binary interchange. Information is passed from transmitters to receivers in a data frame. The data frame is composed of an Arbitration field, Control field, Data field, CRC field, ACK field. The frame begins with a 'Start of frame' [SOF], and ends with an 'End of frame' [EOF] space. The data field may be from 0 to 8 bits. The frame check sequence is derived from a Cyclic Redundancy Code (CRC); the coefficients are generated modulo-2: X15 + X14 + X10 + X8 + X7 + X4 + X3 + 1. CAN implements five error detection mechanisms; 3 at the message level and 2 at the bit level [Also incorporates error flags]. At the message level: Cyclic Redundancy Checks (CRC), Frame Checks, Acknowledgment Error Checks. At the bit level: Bit Monitoring, Bit Stuffing. The CANbus pinout is shown in the table below.
The Application for CAN bus in the automotive area include;
A low speed CANbus may be employed to operate window and seat controls. A high speed CANbus may be employed for engine management or brake control. Many other applications are possible [Engine Sensors, Anti-Skid Systems].
For additional information refer to: CAN Bus Specification; Version 2.0, or ISO 11898/11519.
CANbus is used as a vehicle bus, for other vehicle Buses see the Automotive Bus page {This Site}.
CANbus is also used as an Industrial Field bus, for other Field Buses see the Field Buses page {This Site}
Detailed info on CANbus {Robert Bosch GmbH}, Detailed info on CANbus {KVASER AB}
CAN may also sometimes be seen as Car Area Network
{Industrial CANbus Index}
CAN Bus Pin Out
The pinout for the 9-pin D connector is shown in the table below.
Additional connector styles are listed on the CAN Bus Connector Pin out page, or CAN Bus Round Connector Pin out.
Many of the additional connector pin outs are used with CANopen and include: 10-pin header [5 x 2 multipole], RJ10 [Modular Connector Jack], RJ45 [Modular Connector Jack], 5-pin mini [circular], 5-pin micro [circular], Open Style, 7/8/9-pin round connectors.
9 Pin (male) D-Sub CANbus PinOut Pin # Signal Names Signal Description
1 Reserved Upgrade Path
2 CAN_L Dominant Low
3 CAN_GND Ground
4 Reserved Upgrade Path
5 CAN_SHLD Shield, Optional
6 GND Ground, Optional
7 CAN_H Dominant High
8 Reserved Upgrade Path
9 CAN_V+ Power, Optional
Other CAN info:
- **broken link removed**
- http://cwe.ccsds.org/sois/docs/Work%20Completed%20(Closed%20WGs)/Onboard%20Bus%20LAN%20Working%20Group/ECSS-E-50-NWI-v2_1.pdf
This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
By continuing to use this site, you are consenting to our use of cookies.