Bus Coupling Device Diagnostic Modulation
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Solution Overview
Problem
Existing bus communication devices lack effective diagnostic options for coupling devices and subscriber units, particularly when galvanic isolation is present, limiting the ability to detect errors and transmit diagnostic data without interfering with primary data transmission.
Innovation Solution
A secondary modulation method is introduced on the bus line, allowing for a separate communication channel with a lower data rate, enabling the transmission of non-time-critical information and diagnostic data without disrupting the primary communication protocol, using a modulation with a smaller current gradient that is distinct from the primary modulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a galvanic isolation is implemented between the bus line and subscriber units, then safety and electrical stability are improved, but diagnostic capability deteriorates because error detection becomes impossible
Solution Approach 1:
The coupling device acts as an intermediary component between the bus line and subscriber units, providing galvanic isolation while enabling diagnostic functionality. It includes a diagnostic unit with correlation function evaluation that can detect modulations on the bus line without requiring direct galvanic connection to subscriber units, thus maintaining both electrical stability and diagnostic capability
2Difficulty of detecting and measuring
If a second modulation channel is added for diagnostic data transmission, then diagnostic capability is improved, but interference with primary data transmission may occur
Solution Approach 1:
The patent applies different modulation characteristics to different parts of the signal spectrum. The second modulation channel uses a correlation function with a time course that is correlated to a reference function, while the primary data transmission uses different modulation techniques. This local differentiation in signal characteristics allows simultaneous operation without interference
Solution Approach 2:
The diagnostic data transmission uses parameter changes in the form of current modulations with specific correlation functions that are distinct from primary data transmission parameters. By changing the temporal and spectral parameters of the modulation signals, the system enables dual functionality on the same bus line without mutual interference
3Difficulty of detecting and measuring
If complex communication functionality is added to coupling devices, then diagnostic capability is improved, but device complexity increases
Solution Approach 1:
The coupling device serves as a mediator that provides diagnostic functionality without requiring complex communication capabilities in the subscriber units themselves. The diagnostic unit in the coupling device performs correlation function evaluation to detect errors, while subscriber units remain relatively simple passive devices connected through the intelligent coupling infrastructure
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution allows for independent transmission of error and diagnostic data, enhancing diagnostic capabilities and enabling asset management systems to monitor and control bus communication devices without complex communication functionality, while avoiding interference with the primary data transmission.
Implementation Method 1
The coupling device (17) is set up to carry out a second modulation (M2) of the coupling device current (IK) flowing into the coupling device (17) outside of the communication protocol
Implementation Method 2
Data can be transmitted via the bus line (12) by modulating the subscriber current (IT) consumed by the subscriber unit (14)
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
The invention relates to a bus communication apparatus (10) having a bus line (12), at least one control computer (11) connected to the bus line (12) and also a plurality of subscriber units (14) that are connected to the bus line (12) by means of at least one coupling device (17). The control computer (11) is used to control communication via the bus line (12) using a firmly prescribed communication protocol, and it is possible both for subscriber unit (14) to communicate among one another and for a subscriber units (14) to communicate with the control computer (11) on the basis of the bus protocol. Furthermore, the bus line (12) is used to supply the subscriber units (14) and/or the at least one coupling device (17) with electric power for communication. Each subscriber unit (14) can modulate the subscriber current (IT) on the basis of first modulation (M1) and each subscriber unit (14) and/or each coupling device (17) can modulate the current (IT, IK) on the basis of second modulation (M2). The first modulation (M1) of the subscriber current (IT) is effected in line with the bus communication protocol. The second modulation (M2) of the current (IT, IK) is effected outside the communication protocol totally independently of the data transmission by means of the first modulation (M1). The gradient of the current (IT) is below a gradient maximum in the case of the second modulation (M2) and below the gradient of the subscriber current (IT) in the case of the first modulation (M1).