CAN Protocol Exception State for Mixed Network Communication
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Standard CAN networks are limited by bit duration and the ratio of data bits to control bits, restricting effective data rate, and unmodified standard CAN controllers interfere with CAN FD messages, leading to communication limitations in mixed networks due to error monitoring mechanisms.
Innovation Solution
A method that allows participants to assume a protocol exception state when a control bit deviates from its predetermined value, suspending error monitoring until a resumption condition is met, enabling faster communication protocols like CAN FD without message destruction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If standard CAN error monitoring is applied to CAN FD messages, then transmission reliability is maintained, but data transmission rate is reduced due to message destruction
Solution Approach 1:
The error monitoring mechanism dynamically adapts its behavior based on the protocol exception state. When a control bit deviation is detected, the system transitions from active error monitoring to suspended error monitoring, allowing high-speed CAN FD transmission without message destruction. This dynamic state change resolves the contradiction by making reliability enforcement conditional rather than constant.
Solution Approach 2:
The system changes the monitoring parameter from 'error monitoring active' to 'error monitoring suspended' based on control bit values. This parameter change allows the system to tolerate deviations from standard CAN protocol during CAN FD transmission while maintaining reliability when standard protocol is used, thus enabling high data transmission rates without complete message destruction.
2Adaptability or versatility
If standard CAN protocol is used, then compatibility is maintained, but data rate is limited by bit duration and control bit ratio
Solution Approach 1:
The message structure is segmented into a header portion (with control bits subject to protocol monitoring) and a data portion (where deviations are tolerated in protocol exception state). This segmentation allows standard CAN compatibility in the header while enabling high-speed CAN FD data transmission in the payload section, resolving the contradiction between compatibility and data rate.
Solution Approach 2:
The control bit serves as an intermediary signal that indicates whether standard CAN protocol compliance is required. When the control bit deviates from its predetermined value, it acts as a mediator to trigger the protocol exception state, allowing the system to switch between compatibility mode and high-speed mode based on the message type.
3Ease of manufacture
If unmodified standard CAN controllers are used in mixed networks, then implementation simplicity is maintained, but communication is interfered with due to error monitoring
Solution Approach 1:
The standard CAN controller is enhanced with a dynamic protocol exception state mechanism that activates when control bit deviations are detected. This dynamic adaptation allows unmodified standard CAN controllers to coexist with CAN FD controllers in mixed networks, resolving the contradiction between implementation simplicity and mixed network adaptability.
Data Source
Figure 1a
Figure 1b
Figure 2~3
AI summary
1) Method for the interchange of data between subscribers that are connected to one another by means of a bus system, wherein messages that contain the data are interchanged on the basis of a first communication protocol, wherein the messages comprise a sequence of bits, wherein at least one control bit having a prescribed position within the message that is interchanged on the basis of the first communication protocol must have a prescribed value, wherein for each message one subscriber has the role of the sender and at least one other subscriber, as a receiver, receives the message and performs error monitoring for the message, characterized in that the presence of at least one control bit with a value that differs from the prescribed value prompts at least one receiver to adopt a protocol exception state in which it suspends error monitoring until a resumption condition for the use of the first communication protocol is satisfied.