problem with performing a basic loopback test with NI-6008

[ranjith_poladi]

I have recently started using DAQmx in C# .NET 4.0 with NI-6008 USB DAQ. I tried out a loopback test by connecting an analog output to an analog input and tried readign the signal sent from the output to input but was not successful in sending the signal ( or maybe a problem with the code). The readign from analog input reads a random value rather than the value entered by user for the output. I connected ao0 and ai3 on the DAQ. here is the code.

private void button1_Click(object sender, EventArgs e)

{           

Task analogOutTask = newTask();

 AOChannel myAOChannel = analogOutTask.AOChannels.CreateVoltageChannel("Dev1/ao0", "myAOChannel", 0, 5, AOVoltageUnits.Volts);

 AnalogSingleChannelWriter writer = newAnalogSingleChannelWriter(analogOutTask.Stream);

 double analogDataOut;

 analogDataOut = Convert.ToDouble(AnalogOut.Text);

 writer.WriteSingleSample(true, analogDataOut);

  }

private void button2_Click(object sender, EventArgs e)

 {

           Task analogInTask = newTask();

           AIChannel myAIChannel = analogInTask.AIChannels.CreateVoltageChannel("Dev1/ai3", "myAIChannel", AITerminalConfiguration.Differential, 0, 5, AIVoltageUnits.Volts);

           AnalogSingleChannelReader reader = newAnalogSingleChannelReader(analogInTask.Stream);

           double analogDataIn = reader.ReadSingleSample();

           AnalogIn.Text = analogDataIn.ToString();

}

[Curt_C]

try adding

//Verify the Task
analogInTask.Control(TaskAction.Verify);

//before
//double analogDataIn = reader.ReadSingleSample();

Curt

[ranjith_poladi]

[ranjith_poladi]

As seen in the image above, even after adding the code to verify task. Analog input still shows a random value.

[Curt_C · Accepted solution]

Hi,

I built an app using your code (with task.verify) and it worked just fine.

Have you tried different input/output channels?

Curt

[ranjith_poladi]

Hi Curt,

The problem was with my wiring. I didn't connect the ai3 '-' to the output ground.

I got the right result after doing that.

Thanks for your help.