TDMA Network Node Error Detection via Redundant Bus Monitor
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Solution Overview
Problem
In time-triggered communication systems, especially in safety-critical applications like motor vehicles, there is a need to not only prevent defectively-operating network nodes from accessing the network outside their assigned time slots but also to detect such defects reliably, while existing systems are vulnerable to errors due to the bus monitor's involvement in error detection.
Innovation Solution
A network node design where both the communication unit and bus monitor independently implement an identical access time schedule, providing redundant release signals that are evaluated by the bus driver to ensure accurate error detection and prevent access to the communication medium in case of discrepancies, with additional measures like inverse coding and low-pass filtering to suppress errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the bus monitor independently implements error detection by comparing transmission requests with access time schedule, then error detection capability is improved, but the system becomes vulnerable to errors in the bus monitor itself
Solution Approach 1:
The invention creates a redundant copy of the access time schedule implementation by having both the communication unit and bus monitor independently implement identical access time schedules. This allows cross-verification of transmission requests against multiple independent schedule implementations, preventing errors in a single implementation from going undetected.
Solution Approach 2:
The bus driver acts as an intermediary that receives release signals from both the communication unit and bus monitor, compares them, and controls actual bus access. This intermediary layer prevents direct trust in either the communication unit or bus monitor alone, adding a verification step that blocks defective access.
2Reliability
If the communication unit and bus monitor both implement identical access time schedules independently, then error detection reliability is improved, but device complexity increases
Solution Approach 1:
The bus driver performs multiple functions: it acts as a comparator between release signals, serves as a block for defective access, and controls the actual bus transmission. This multi-functionality reduces the need for separate dedicated components, managing complexity while maintaining reliability.
3Reliability
If the bus driver evaluates release signals from both communication unit and bus monitor, then error suppression is improved, but additional control logic complexity increases
Solution Approach 1:
The system uses its own internal components (bus driver) to perform the evaluation and blocking function, rather than introducing an external monitoring system. The bus driver self-manages the comparison and blocking logic, reducing overall system complexity while maintaining error suppression capability.
Data Source
AI summary
A network node (1) with a communication unit (2), which is provided for the implementation of a communication protocol for the purpose of communication with other network nodes via a communication medium (5), and with a bus monitor (3), which, mutually independently, each implement an access time schedule contained in a configuration data record, and which each make available, in accordance with the access time schedule, a release signal for a bus driver (4) provided in the network node (1), which evaluates these two signals and, in the event that the two release signals do not coincide, blocks the access of the network node (1) to the communication medium (5).