Support Question of the Week: How Do I Configure Conditions for a USB Protocol Analyzer to Capture Data and Stop when Errors Occur?

I plan to run a design verification tests (DVT) for long periods. For part of the DVT, I'll need to continue running the test and capture data as errors occur. For another part of the DVT, I'll need to capture data and stop running the test when an error occurs. Which USB protocol analyzer do you recommend, and how can I run and capture the data as described?

Thanks for your question! Both the Beagle USB 5000 Protocol Analyzer and the Beagle USB 480 Power Protocol Analyzer have the ability to trigger on errors during a long-term capture. They can be set up to capture data and run continuously or to start a capture when a certain trigger event occurs, such an error. Using the Data Center Software with these protocol analyzers, you can analyze and capture all data, set up a trigger for your event of interest only, run firmware validation, bring up new USB devices, as well as other features for capturing and analyzing data.

There are two methods for trapping an error over an extended capture period:

  • Capture all data and search for the error(s) in the log - this method will require a large amount of storage.
  • Use the Complex Match feature to set up a trigger and only log the traffic around the trigger.

To use Complex Match, first set up a trigger condition and then start the capture. The Beagle USB Protocol Analyzer will then run in a “pre-trigger” mode until the trigger condition is met. During the pre-trigger mode, the protocol analyzer captures traffic in a circular buffer and retains only the most recent records. The amount of data that can be saved is determined by the on-board memory buffer you set aside for that purpose.

Once the trigger condition is met, the Data Center Software will download the data in the pre-trigger buffer. You can configure the device to continue to continue running or to stop almost immediately. There are two ways to continue running the capture:

  • Continue capturing data - it will stop when all the storage space is filled.
  • Program the analyzer to loop while filtering out most of the packets, which simulates a stop. The advantage of this approach is that you can capture indefinitely while looking for the error. Note - this method is limited to configuring one trigger condition for a capture - you can define a very detailed trigger condition.  An example of using Complex Match to configure a trigger is shown below in Figure 1.
Using Data Center Software option of Complex Match to set up a trigger Figure 1: Data Center Software showing Complex Match


  • The Data Center Software can display cumulative errors, which is accessed by using the Statistics Tab of the Navigator pane. In this case, the display shows both the gross and the breakdown of errors are displayed, as well as other information.
  • You can narrow the scope of the statistics by selecting the various levels in the bus tree in the Navigator screen. The statistics are live while a capture is running, as shown below in Figure 2.
Selecting data for viewing Figure 2: Data Center Software Panes


  • The LiveFilter feature can be used to display only the errors in the Transaction Window, as shown below in Figure 3.
 Data Center Software Errors Only Transaction Window Figure 3: Data Center Software Errors Only Transaction Window

For information about errors that could be viewed it the Transaction log error column, please refer to section 6.6, Table 7 of the Data Center Software User Manual.

For information about errors what could be viewed when using the Complex Match feature, please refer to section 6.3.10, Figure 57 of the Data Center Software User Manual.

For additional information, please refer to the following documents:

If you have other questions about our analyzers or other Total Phase products, feel free to email us at  or submit a request for technical support.




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