CAN-FD Bus Transmitter Bit Rate Switching Verification
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Solution Overview
Problem
Existing methods for testing specification-compliant behavior of transmitters and receivers on a CAN FD bus, particularly in error conditions, are inefficient and prone to collisions, and do not reliably verify bit rate switching as per the standard.
Innovation Solution
A method involving a function generator and a measuring device to send a test signal with two CAN messages of the highest priority, where the second message contains an error introduced by breaking off user data at a higher bit rate, ensuring the bus device switches to the lower bit rate for error message transmission, allowing for precise measurement of the error message length.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing testing methods are used to verify bit rate switching on CAN FD bus, then testing can be performed, but collisions occur and the testing is inefficient and unreliable
Solution Approach 1:
The patent applies preliminary action by using a function generator to send a first test message with highest priority (identifier 0) before the actual error condition test. This preliminary message ensures the bus is ready and prevents collisions during the error message transmission, making the subsequent bit rate switching verification reliable and efficient
2Measurement precision
If error messages are sent during high bit rate data transmission, then bit rate switching can be verified, but message collisions may occur
Solution Approach 1:
The function generator sends a preliminary first message with identifier 0 (highest priority) before introducing the error condition in the second message. This preliminary action secures bus access and prevents collisions when the error message is transmitted at nominal bit rate, ensuring reliable measurement of error message length
Solution Approach 2:
The patent applies local quality by manipulating only the second message to contain an error condition (breaking off user data at high bit rate), while keeping the first message as a clean test signal. This localized manipulation allows precise verification of bit rate switching without affecting other parts of the test signal
Data Source
Figure 1
AI summary
The invention relates to a method for testing the specification-compliant behavior of transmitters and receivers on a CAN-FD bus in the event of a fault. The object of the invention is to propose a test method that ensures a simple and reliable verification of bit rate switching according to the CAN-FD standard.According to the invention, the problem is solved by a method for checking the specification-compliant behavior of bus participants on a CAN-FD bus with the following steps: - Integrating a function generator and a measuring device into the CAN-FD bus of a network consisting of a CAN-FD controller and a bus participant under test, which are in communication, - Generating a test signal (3) at the function generator, containing a first message (1) and a second message (2), wherein the first message (1) is a specification-compliant message and the second message (2) is a faulty message, - Recording and checking a signal waveform of an error message (E) (error frame) of the bus participant under test following the test signal (3).