How to stream values from your Simulink Real-Time™ (xPC) model
Published on 8th August 2017
Posted in in Software updates and patches
To support the ever-growing demands of monitoring high speed model data for the purposes of testing, sufficiently capable interfaces are needed which move away from traditional polling methods and support streaming instead.
Polling is where a signal is requested from the target system each time the value is required. This is a slow mechanism, due to the small transfer sizes and the fact that two way communications takes place for each sample request.
Streaming is where a signal is requested only once in a way that the target system continuously sends the data without being asked again, reducing bandwidth by 50%, when compared to polling. During the running of a system, the signal is continuously broadcast from the target model in such a way that a graphical user interface (GUI) can collect every sample and display them.
Generally, when displaying text values with lower sample rate models, the Simulink Real-Time™ API is sufficient to meet the demands for many controls and for complex user interface requirements. However, when trying to stream signals less than 100ms, the non-real-time nature of Windows is likely to cause sample time jitter and in extreme cases, data loss.
We’ve developed an API that sits alongside Simulink Real-Time™ which makes the above issues redundant, due to its real-time capability. It allows engineers to view and log intermediate data produced at any point in a Simulink® model. It facilitates the following functionality:
- Streaming support
- Enhanced control of the way data is sent
- The communications protocol layer for all streamed data
- Buffering of the real-time data between the GUI and the model data
Using a GUI such as VISUALCONNX, our real-time systems interface creation package, it is possible to collect and display all signal data for the purposes of logging the data to disk or displaying on a high speed, real-time graph.
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