Why controller area network

The use of differential voltage contributes to the vast reliability of CAN. Even though extremely effective in automobiles and small, embedded applications, CAN alone is not suitable for projects that require a minimum of network management and messages with more than eight data bytes. As a consequence, higher-layer protocols additional software on top of the CAN physical layer such as CANopen for industrial automation and SAE J for off-road vehicles were designed to provide an improved networking technology that support messages of unlimited length and allow network management, which includes the use of node IDs CAN supports only message IDs where one node can manage multiple message IDs.

Ironically, however, it is very well foreseeable that the basic CAN technology will prevail over higher-layer protocols for the automation industry such as CANopen and DeviceNet, specifically due to its continued use in automobiles.

The only exception is SAE J, which is closely connected to the diesel engine technology and that includes, yet again, vehicles. Note : I personally consider CANopen to be a fairly complex and tremendously over-bloated protocol with a disappointingly low bandwidth. Add to this that CANopen is rapidly losing its attraction for the automation industry due to the emergence of the more powerful Industrial Ethernet protocols, and now there are two reasons why I never attempted writing a CANopen stack.

The Society of Automotive Engineers SAE Truck and Bus Control and Communications Subcommittee has developed a family of standards concerning the design and use of devices that transmit electronic signals and control information among vehicle components.

SAE J and its companion documents have quickly become the accepted industry standard and the Controller Area Network CAN of choice for off-highway machines in applications such as construction, material handling, and forestry machines. Newer models of automobiles may have more than 70 Electronic Control Units ECU , of which the most important is the engine control unit.

Communication between these nodes is very important, as data is constantly being transported between these nodes. The CAN system was developed in order to fill in the communication gaps which often arise when a particular subsystem of ECUs needs information from a sensor in another subsystem. One of the best features of such communications is that the vehicle can actually respond to certain situations quickly, and it is much less expensive to implement when compared to those features which are wired in the vehicle system.

However, the scope of the Controller Area Network is not limited to vehicular communications only. These systems are also used in communication between the different microcontrollers in embedded systems and also in the communication systems for smart devices. By: Justin Stoltzfus Contributor, Reviewer. Engineers can decode SENT signals from multiple sensors simultaneously where each sensor is using a different counter, by adding multiple module windows.

SENT channels are available as Dewesoft channels. FlexRAY is a protocol used for dynamic automotive applications such as chassis control. FlexRAY transmits data over one or two unshielded, twisted pair cables. It runs at 10 Mbps and supports one or two-wire configurations. Bus, star, and hybrid network topologies are supported, at speeds up to 10 Mbps. Differential signaling keeps noise low without the need for shielded cables, which adds cost and weight. CAN uses an arbitration bit to determine which data gets priority and is allowed to proceed.

This avoids collisions and allows higher overall throughput of data across the bus due to the high overall data rate of the bus. Star topology has the advantage of not allowing a wiring fault to affect more than one node. FlexRAY can also be implemented in a mixed topology, as shown below. FlexRAY is used most often for high-performance powertrain, safety, and active chassis control applications. However, when dual pairs of parallel data lines are used, this provides redundancy: when a line is damaged, the second line can take over.

This is important in mission-critical applications like steering and braking. FlexRAY applications that are not mission-critical typically use a single twisted pair.

A software plugin is available to support all Vector FlexRay interface cards. LIN is a serial unidirectional messaging system, where the slaves listen for message identifiers addressed to them. Because of its lower bandwidth and node count limitations, LIN is normally used to control small electric motors and controls. LIN is limited to Adjustable car seat controls in a Mercedes-Benz Image courtesy of Pixabay. It is used for low-bandwidth applications such as electric windows, lights, door locks, keycard entry systems, electric mirrors, power seats, and similar.

Decoding can be done in three different forms:. As with any networking and interoperable system, automotive bus choice is best driven by the requirements of the application, while keeping an eye on cost and projected industry requirements and trends. The CAN bus interfaces provided as standard or optional with Dewesoft systems provide a high level of capability, as well as extensibility to additional protocols.

All Dewesoft CAN interface are galvanically isolated , protecting the instrument and connected devices from ground loops and other electrical disturbances. DBC files are a standard format that allows engineers to parse the data stream into individual channels with names, scaling, proper engineering units, and more.

DewesoftX CAN main setup screen. DewesoftX CAN bus channel setup screen, showing five different channels contained within a single message. DewesoftX makes it extremely easy to configure CAN channels.

Dewesoft was among the first DAQ system makers to fully implement CAN bus interfaces with their analog data acquisition system. Nearly every Dewesoft DAQ system has at least one CAN bus interface built-in as standard, and an additional dedicated CAN interface can be added internally, externally, or both, while still maintaining perfect synchronization. Dewesoft CAN interface is also galvanically isolated, protecting both the instrument and the bus itself from ground loops and other electrical problems.

Today, Dewesoft offers support for several standard automotive interfaces for analyzing and inspecting vehicle bus data. Data can be captured from all the supported interfaces and synchronized with other sources like analog, video, and others. It supports high-speed CAN data rates up to 8 Mbps. The power limit of the sensor supply is 1.

Feb Learn more: Dewesoft CAN interfaces. Share this article:. Related Articles. Read more ». The single dominant Start Of Frame. This bit marks the start of a message. Google Scholar. CAN specification version 2. Hansson, J. Axelsson, and B.

A comparative case study of distributed network architectures for different au-tomotive applications. Kiencke, S. Dais, and M. Automotive serial controller area network. Kiencke and L. Automotive Control Systems. Springer-Verlag, Berlin, Kluwer Academic Publishers, Dordrecht, Leen and D.