How CAN bus transmits Chengdu Panfeng Technology

How the bus transmits Chengdu Panfeng Technology
The bus transmits data in units of messages. The priority of the message is combined with the identifier (bit or bit). The identifier with the lowest binary number has the highest priority. Conflicts in bus reads are resolved through bit arbitration. When several stations send messages at the same time, the station sending the message with the highest priority will gain control of the bus. The advantage of this non-destructive bit arbitration method is that the initial part of the message has been transmitted on the network before the network finally determines which station's message is transmitted. Automotive Bus Simulation Development Tool All stations that have not obtained bus read rights become receiving stations for messages with the highest priority and will not send messages until the bus is free again.
The unit that sends a message during data transmission is called the sender of the message. This unit remains a transmitter until the bus is idle or arbitration is lost. A unit is a receiver if it is not a message sender and the bus is not idle. The actual valid time of the message is different for the message sender and receiver. For the sender, a message is valid for the sender if no error occurs until the end of the frame. If the message is damaged, automatic retransmission in priority order is allowed. In order to compete with other messages for bus access, retransmission starts as soon as the bus is idle.
For the receiver, if the last bit at the end of the frame is known to be correct, the message is valid for the receiver. The frame start, president field, control field, and data field sequences that constitute a frame are all encoded with the help of bit stuffing rules. When the transmitter detects consecutive bits of the same value in the transmitted bit stream, it will automatically insert a complement bit in the actual transmitted bit stream. The remaining bit fields of data frames and remote frames are in a fixed format and are not padded. Error frames and overload frames are also in a fixed format and do not perform bit stuffing.
The bit stream in the message is encoded according to the non-return-to-zero code method, which means that the bit level of a complete bit is either or. Message transfers are represented and controlled by different types of frames: Data frames carry data sent from the transmitter to the receiver Remote frames are sent by the bus unit to request the transmission of a data frame with the same identifier Error frames are sent by any unit that detects a bus error Overload frames are issued to provide additional time delays for the current and subsequent data frames.
When a node (station) on the bus sends data, it is broadcast to all nodes in the network in the form of a message. For each node, it receives the data regardless of whether it is sent to itself. The bit characters at the beginning of each group of messages are identifiers (bits in the extended frame format) and define the priority of the message. The identifier is unique in the same system and it is impossible for two stations to send messages with the same identifier. This configuration is important when several stations compete for bus reads at the same time.
When a station wants to send data to other stations, the station transmits the data to be sent and its own identifier to the chip of the station and is in a ready state. When it receives the bus allocation, it switches to the message sending state. The chip organizes the data into a certain message format according to the protocol and sends it out. At this time, other stations on the network are in the receiving state. Each station in the receiving state detects the received messages to determine whether these messages are sent to itself to determine whether to receive and process them.