How Do I Use a USB Protocol Analyzer to Debug a Serial-USB Interface?
2024-09-04
Rena Ayeras

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Question from the Customer:

I am debugging a communication error that involves a serial interface and a USB bus. With the tools I have, I cannot identify the cause for this error, which could be on either or both sides of the serial-USB interface. I need a protocol analyzer to analyze and identify the root cause of this issue.

Here is a high-level diagram of the setup:

To monitor the USB bus, as well as RS232 or RS485, which protocol analyzer do you recommend for this project?

Response from Technical Support:

Thank you for your question! For the USB side of the Serial to USB Interface, our Beagle USB Protocol Analyzers can monitor real-time packet level data up to USB 3.1 SuperSpeed Gen 1 (5 Gbps). To help you with your project, we will provide an overview of our Beagle USB analyzers, information about how to use these tools, and an example of using a USB analyzer to monitor an RS232 interface.

Selecting USB Protocol Analyzers

For an overview of our Beagle USB analyzers, refer to our USB Analyzer Guide to easily compare their features. To see what you can do with our Beagle USB analyzers, here are some videos that demonstrate using these tools for various applications:

Monitoring the Serial Interface with a USB Protocol Analyzer

Our protocol analyzers do not directly monitor the RS232 or RS485 serial interfaces. However, we have a functional known workaround what uses the Beagle USB 480 Protocol Analyzer with a third-party USB to RS232 converter (Serial to USB converter) and a Beagle Software API script. Here is a diagram of a Beagle USB 480 analyzer in that setup:

Here is an example of captured data displayed with the Data Center Software. It shows the actual packets sent between the UART and the terminal emulator.

For more information of this example, please refer to How Do I Monitor UART Data Over the RS232 Bus with a USB Protocol Analyzer?

We hope this answers your question. Additional resources that you may find helpful include the following:

If you want more information, feel free to contact us with your questions, or request a demo that applies to your application.