Acquire Data in the Background
This example shows how to acquire data in the background using callbacks while MATLAB continues to run.
A background acquisition depends on callbacks to allow your code to access data as
the hardware acquires it and to react to any errors as they occur. In this example, you
acquire data from an NI 9205 device with ID
cDAQ1Mod1 using the
ScansAvailableFcnCount property to trigger the function call
defined by the
Create an NI DataAcquisition object with an analog input voltage channel on
d = daq("ni"); ch = addinput(d,"cDAQ1Mod1","ai0","Voltage");
Create a simple callback function to plot the acquired data and save it as
plotMyData.m in your working directory. Enter the following
code in the file:
function plotMyData(obj,evt) % obj is the DataAcquisition object passed in. evt is not used. data = read(obj,obj.ScansAvailableFcnCount,"OutputFormat","Matrix"); plot(data) end
Set the callback function property to use your function.
d.ScansAvailableFcn = @plotMyData;
Start the acquisition to run for 5 seconds in the background.
Speak into the microphone and watch the plot. It updates 10 times per second.