The CAN protocol is a widely used communication standard in automotive and industrial applications. It has been standardized by the International Organization for Standardization (ISO), with two main versions: ISO 11898 and ISO 11519-2. Both standards define the data link layer in the same way, but they differ significantly in their physical layer specifications.
ISO 11898 is designed for high-speed CAN communication, typically operating at speeds up to 1 Mbps. Originally, this standard included both the data link and physical layers. However, it was later split into two parts: ISO 11898-1, which covers only the data link layer, and ISO 11898-2, which focuses on the physical layer. This division allows for more flexible and specialized implementation of CAN systems.
On the other hand, ISO 11519-2 is intended for low-speed CAN communication, with maximum speeds of up to 125 kbps. It is often used in applications where cost and simplicity are key factors, such as in certain vehicle control systems or industrial automation setups.
The differences between ISO 11898 and ISO 11519-2 can be seen in various aspects of the physical layer. These include the signaling method, voltage levels, and termination requirements. For example, ISO 11898 uses a differential signaling approach with specific voltage thresholds for dominant and recessive states, while ISO 11519-2 may have different tolerances and configurations.
In terms of bus topology, a typical CAN network consists of two wires—CAN_High and CAN_Low. The potential difference between these two lines determines the bus state. There are two levels: dominant (representing a logical '0') and recessive (representing a logical '1'). When a node transmits a message, it changes the bus level accordingly, allowing all nodes on the network to receive the information.
The physical layer also defines the required termination impedance, which is crucial for signal integrity. Different standards may require different types of transceivers to ensure compatibility and proper operation. For instance, ISO 11898 and ISO 11519-2 each specify their own transceiver ICs that must be used to meet the respective standards.
Beyond ISO, other organizations such as SAE (Society of Automotive Engineers) and NMEA (National Marine Electronics Association) have also contributed to the development and standardization of CAN-based protocols. These standards help define communication methods for different application areas, such as automotive, marine, and industrial systems.
For example, SAE has developed several standards like J1850, which is used in some vehicle networks, while NMEA provides guidelines for marine electronics. Additionally, private companies and research institutions have created proprietary CAN protocols tailored for specific use cases.
Understanding the differences between these standards is essential when designing or implementing a CAN-based system. Factors such as communication speed, bus length, and environmental conditions must be carefully considered to ensure reliable and efficient data transmission.
By selecting the appropriate standard and components, engineers can build robust and scalable CAN networks that meet the needs of modern automotive and industrial applications.
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2. Design Configurations
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Advantages of Photovoltaic noise barrier
✅Space Efficiency:Uses existing noise barrier infrastructure,avoiding additional land use.
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Challenges&Considerations
âš Lower Efficiency:Vertical mounting may reduce solar output compared to optimally tilted panels.
âš Shading&Orientation:Barriers along north-south roads may have uneven sunlight exposure.
âš Maintenance:Cleaning panels on highways/railways can be logistically challenging.
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