How do CAN bus communication networks typically transmit data between control system components?

CAN (Controller Area Network) bus communication networks typically transmit data between control system components using a two-wire, differential signaling method. Differential signaling means that data is transmitted as a voltage difference between the two wires, rather than as a voltage level referenced to ground. This method is highly resistant to noise and interference, which is crucial in electrically noisy environments like those found in heavy machinery. Each device on the CAN bus, such as sensors, actuators, and controllers, has a unique identifier. Data is transmitted in the form of messages, each containing an identifier that indicates the message's priority and the type of data it contains. When a device wants to transmit data, it broadcasts a message onto the bus. All other devices on the bus receive the message, but only the device with the matching identifier processes the data. This is known as message filtering. If two devices attempt to transmit simultaneously, a process called arbitration occurs. The device with the higher-priority identifier (lower numerical value) wins the arbitration and continues transmitting its message, while the other device waits. This ensures that important messages are transmitted first. The CAN bus uses a twisted-pair cable with a characteristic impedance of 120 ohms, terminated with resistors at each end to prevent signal reflections. Data is typically transmitted at speeds ranging from 125 kbps to 1 Mbps, depending on the application. For example, in a modern excavator, the engine control unit (ECU), hydraulic controller, and operator display communicate over the CAN bus, sharing information about engine speed, hydraulic pressure, and joystick position.