Multi-Drop MAC and Physical Layer for Industrial Ethernet
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Solution Overview
Problem
Conventional Ethernet and wireless technologies are costly and unreliable for supporting TCP/IP communications in industrial process control and automation systems, particularly due to their intolerance to multiple device failures and requirement for external switches, which is undesirable in critical control applications.
Innovation Solution
The implementation of media access control (MAC) and physical layer techniques that enable high-speed Ethernet-based communications over shared physical media with multi-drop capability, allowing multiple devices to share a common medium, thereby simplifying installation and reducing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Ethernet technologies are used for industrial process control and automation systems, then TCP/IP communications can be supported, but system costs increase due to requirement for external switches
Solution Approach 1:
The patent merges the functions of multiple devices into a single shared physical medium, allowing multiple industrial process control and automation devices to communicate over a common bus without requiring external switches. This combining approach eliminates the need for separate switch infrastructure while maintaining TCP/IP communication capabilities.
Solution Approach 2:
The shared physical medium serves multiple functions simultaneously - it acts as a communication bus for TCP/IP communications, supports multiple devices with multi-drop capability, and provides high-speed data transmission without requiring device-specific switch infrastructure. This universal medium replaces what would traditionally require multiple specialized components.
2Device complexity
If Ethernet rings are used to avoid external switches, then device complexity is reduced, but reliability deteriorates due to intolerance to multiple device failures
Solution Approach 1:
The patent segments the communication medium into a multi-drop bus architecture where multiple devices can independently access the shared medium. This segmentation allows individual device failures to be isolated without completely breaking communications, as other devices can continue to transmit and receive data on the same bus.
Solution Approach 2:
The patent changes the topological parameter from a closed ring structure to an open multi-drop bus structure. This parameter change fundamentally alters the failure characteristics - in the multi-drop configuration, a single device failure does not break the communication path for other devices, thereby improving fault tolerance while maintaining simplicity.
3Device complexity
If RS485 bus is used for shared medium communications, then device complexity is reduced, but transmission speed deteriorates below 10 Mbps
Solution Approach 1:
The patent changes the transmission speed parameter from the traditional RS485 limit of below 10 Mbps to high-speed operation exceeding 10 Mbps. This is achieved by implementing a custom physical layer that maintains the multi-drop bus architecture while using enhanced signaling and timing mechanisms to achieve Ethernet-compatible speeds.
Solution Approach 2:
The patent substitutes the traditional RS485 physical layer implementation with a high-speed physical layer designed for multi-drop capability. This substitution replaces the slower, conventional serial communication mechanism with a faster transmission system that can operate at Ethernet speeds while maintaining the shared medium topology.
Data Source
AI summary
An apparatus includes at least one transceiver configured to transmit or receive at least one data signal over a shared physical medium. The physical medium includes a bus configured to be coupled to multiple devices including the apparatus and provides a multi-drop capability. The at least one transceiver is configured to transmit or receive the at least one data signal at a rate of more than 10 Mbps. In some embodiments, the apparatus includes a MAC driver configured to route network layer data over the physical medium. In other embodiments, the apparatus includes a MAC driver configured to control transmissions and receptions of network layer data over the physical medium by the at least one transceiver and a logic device configured to control physical layer signaling, interface with the MAC driver, enable the transmissions and receptions of the network layer data on the physical medium, and implement collision detection and avoidance.