Filtering in real time from a NI DAQ

Hello Guys, I'm trying to acquire an analog signal (coming from a sensor) from a NI DAQ board and I would like to manage better the plot and filtering in real time in Matlab. I'm acquiring in background operation. What is hard is how to have access to the data (from the listener) for processsing: I'm able to plot only one second of data. Does someone knows how to solve this? Thank you

Answer 1

[Vandana Ravichandran]

Please try the "DurationInSeconds" property of the session object. You can create a listener using "addlistener" function that calls the "plot" Callback for the "DataAvailable" event. "DurationInSeconds" can be used to control for how long the background operation runs and the data is acquired for this duration. Once this interval completes, the listener invokes the "plot" callback.

The documentation has an example similar to what you want to implement: https://www.mathworks.com/help/daq/ref/dataavailable.html

[Marco Tito Scordo]

Hello Vandana Ravichandran, thank you for your asnwer. At my knowledge, Duration in Seconds is used for managing duration of the acquisition only. So if I want to acquire 1min of signal it will have a value of 60, but the plot will show always 1 sec of aquisition 60 times. If I want to see 5 sec of signal in real time the problem is not solved and I don't have access to data anyway. Do you think is possibile another way to do it? Thank you

[Walter Roberson]

How are you doing the plotting?

The callback on the listener should have access to all of the data made available. However if you happened to be plotting in Simulink with a Scope block then that block might be configured to retain a limited number of points.