CAN Flavours or Automotive protocols!

There are other protocols in the Automobile industry like CAN.

THE ISO-TP PROTOCOL:

This is used to send data up to 4095bytes by linking/chaining the CAN packet’s together, this is a standard for sending packet water can purse that extends to do this encapsulation first byte is used and leaving the rest 7 bytes for data.

THE CANOPEN PROTOCOL:

CANopen breaks the 11bit identifier to 4bit function code & 7bit node ID ( this combination is known as a communication object identifier (COB-ID) ). This is mostly used in industrial settings than in Automotive.

THE GMLAN BUS:

This is an implementation by General Motors, GMLAN bus consists of a single-wire low-speed and a dual wire high-speed bus. The low-speed bus, a single-wire CAN bus that operates at 33.33Kbps with a maximum of 32 nodes, is to lower the cost of communication and wiring. It is used to transport non-critical information for things like the infotainment center, HVAC controls, door locks, immobilizers, etc. the high-speed bus runs at 500Kbps with a maximum of 16 nodes. Nodes in a GMLAN network relate to the sensors on that bus.

THE SAE J1850 PROTOCOL:

There are two types of these, pulse width modulation (PWM) and variable pulse width (VPW). There are three classes A, B, C which work at 10.04kbps,100kbps,1Mbps respectively.

A — is used in business, industrial, and commercial environments.
B — in residential environments.
C — in real time-critical systems and media networks.

The VPW Protocol:

It is a single wire bus system that runs at 7v and 10.4kbps. VPW uses time-dependent signaling receiving a bit is determined by sustaining for a certain amount of time.

The Keyword Protocol and ISO 9141–2:

Messages sent using KWP2000 may contain up to 255 bytes. the ISO 14230–4 KWP has two variants as 5-baud init & fast init. Unlike CAN packets, K-Line packets have a source and destination address. K-Line can use a similar PID request structure as CAN.

The Local Interconnect Network (LIN) Protocol:

LIN is a cheaper protocol this will not have any arbitration/priority code, all the data transmission is done by a single master node. One master node can support up to 16 slave nodes that respond according to a certain event. generally, the master node is connected to the CAN network. LIN works at 12v & 20kbps. LIN message will have a Header given by the master and response of it.

The MOST Protocol:

The Media Oriented Systems Transport (MOST) protocol is designed for multimedia devices that can hold a maximum of 64 devices out of them one will be a master and feeds the frames into the ring. It runs at 23 Mbaud and supports various audio/video channels. It uses a dedicated control channel to send configuration messages which run at 768 Kbaud. It comes in three variants,

• MOST25 — runs on plastic optical fiber and transmission is done at 650 nm.
• MOST50 — doubles the bandwidth and increases the frame length to 1025 bits and transports in un-shielded twisted-pair (UTP).
• MOST150 — implements Ethernet and increases the frame rate to 3072 bits or 150 Mbps.

MOST has three channels:
Synchronous — Streamed data (audio/video)
Asynchronous — Packet distributed data (TCP/IP)
Control — Control and low-speed data (HMI)
MOST automatically assigns addresses in the ring it also routes packets through the separate import and out-port ports.

The Flex-Ray Bus:

This is a high-speed bus that is capable of communicating up to 10 Mbps mainly used for taking real quick decisions. Flex-Ray is costlier due to its perks and is used for high-end systems. It uses a twisted pair wiring also supports a dual-channel this helps in an increase of fault tolerance and bandwidth. Flex-Ray supports bus and star topology we can also combine them to make a hybrid layout.

Automotive Ethernet:

FlexRay and MOST are costly to implement most of the automobiles are alternating to Ethernet. Only the implementation varies from the Standard network of computers. Data is transmitted using UDP and VoIP at speeds up to 10Gbps irrespective of topology.