Field Bus Communication Protocol with Presence Detection and Priority Arbitration
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Solution Overview
Problem
Existing field bus systems face challenges in maintaining efficient digital communication, particularly in high-traffic systems like building control and process control systems, where low-priority messages can be lost due to high traffic and event-driven protocols, leading to delays or loss of critical information.
Innovation Solution
A method for digital communication over a field bus that includes a first mode where nodes respond synchronously to a broadcast polling message with a data word, allowing the master node to determine operational nodes and provide a presence detection mechanism, and a second mode based on message priorities, using bitwise arbitration to ensure high-priority messages are transmitted first, thereby optimizing communication efficiency and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If event-driven protocol with priority-based message transmission is used, then high-priority messages are transmitted first, but low-priority messages may be lost or delayed in high-traffic systems
Solution Approach 1:
The patent segments the communication protocol into two distinct modes: event-driven mode for high-priority urgent messages and cyclic mode for regular status updates. This segmentation allows low-priority messages to be transmitted reliably through cyclic polling while high-priority messages use interrupt-driven transmission, preventing loss of either message type
Solution Approach 2:
The system dynamically switches between event-driven and cyclic communication modes based on message priority and system state. The master station can transition from cyclic polling to event-driven interruption when urgent messages occur, and vice versa, optimizing both reliability and information completeness
2Reliability
If processing speed and communication bandwidth are increased to reduce message loss, then message transmission reliability improves, but component cost increases and compatibility with existing infrastructure is reduced
Solution Approach 1:
The patent changes the operational parameters of the existing field bus system by implementing dual communication modes rather than increasing hardware speed or bandwidth. The system maintains compatibility with existing infrastructure while improving reliability through protocol optimization - using cyclic mode for regular traffic and event-driven mode for urgent messages
3Reliability
If cyclic enquiries are used to poll all bus participants, then all nodes are checked for messages, but bus time is lost when participants have no messages to send
Solution Approach 1:
The system uses event-driven interruption where slave stations automatically interrupt the master station when they have urgent messages to send, eliminating the need for continuous cyclic polling. This self-service mechanism ensures complete message collection while minimizing bus time waste, as the bus is only actively used when there is actual communication needed
Data Source
AI summary
The present invention provides, inter alia, a method for digital communication between at least one first node and a plurality of second nodes which are connected with the first node by a field bus. According to one aspect a highly effective presence detection scheme for checking the operational status of the second nodes by the first node is integratively combined with a message query for providing an effective first mode of digital communication between said nodes, which may be used very effectively to provide a communication channel which is independent of message priorities. According to another aspect the first mode of digital communication is combined with a second mode of digital communication which is based on message priorities of digital messages to be send by a respective second node to the first node. To advantage, a bitwise bus access arbitration mechanism may be used for implementing those modes of communication.