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Simultaneously Acquire Data and Generate Signals

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This example shows how to acquire and generate data using two National Instruments™ modules operating at the same time.

Create a DataAcquisition

Use daq to create a DataAcquisition

dq = daq("ni")

dq = 

DataAcquisition using National Instruments hardware:

                     Running: 0
                        Rate: 1000
           NumScansAvailable: 0
            NumScansAcquired: 0
              NumScansQueued: 0
    NumScansOutputByHardware: 0
                   RateLimit: []

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Set up Hardware

This example uses a compactDAQ chassis NI c9178 with NI 9205 (cDAQ1Mod1 - 4 analog input channels) module and NI 9263 (cDAQ1Mod2 - 4 analog output channels) module. Use daqlist to obtain more information about connected hardware.

The analog output channels are physically connected to the analog input channels so that the acquired data is the same as the data generated from the analog output channel.

Add an Analog Input Channel and an Analog Output Channel

Use addinput to add an analog input voltage channel. Use addoutput to add an analog output voltage channel.

addinput(dq, "cDAQ1Mod1", "ai0", "Voltage")
addoutput(dq, "cDAQ1Mod2", "ao0", "Voltage")

Create and Plot the Output Signal

output = cos(linspace(0,2*pi,1000)');
plot(output);
title("Output Data");

Generate and Acquire Data

Use readwrite to generate and acquire scans simultaneously.

data1 = readwrite(dq, output);

Plot the Acquired Data

plot(data1.Time, data1.Variables);
ylabel("Voltage (V)")
title("Acquired Signal");

Generate and Acquire Data for Twice the Previous Duration

data2 = readwrite(dq, [output; output]);

Plot the Acquired Data

plot(data2.Time, data2.Variables);
ylabel("Voltage (V)")
title("Acquired Signal");