Hello,
I am attempting to read 8 channels of analog input data. The analog waveform is a 60Hz AC voltage, and I want to read 500 samples at 5kHz. Then, I want to use the 500 samples to compute the RMS voltage for each channel. I have successfully been able to do so, however, the acquisition time is way too long (about 3 seconds per update).
Here is the code:
public void UpdateVoltages()
{
try
{
Console.WriteLine("begin read...");
// capture the waveform for each channel (for increased performance)
voltageReader.BeginReadWaveform(500, new AsyncCallback(voltageWaveformReadCallback), null);
DAQtimer.Stop();
}
catch (Exception ex)
{
Console.WriteLine(ex.Message);
StopDAQ();
}
and the callback:
private void voltageWaveformReadCallback(IAsyncResult result)
{
try
{
Console.WriteLine("Read waveform begin...");
AnalogWaveform<Double>[] voltageWaveform = voltageReader.EndReadWaveform(result);
Console.WriteLine("Read waveform completed");
int i = 0;
while (i < voltageWaveform.Length)
{
double rmsValue = NationalInstruments.Analysis.Math.Statistics.RootMeanSquared(voltageWaveform[i].GetRawData());
RMSvoltages.SetValue(rmsValue, i);
i++;
}
DAQtimer.Start();
Console.WriteLine("end RMS calc...");
}
catch (Exception ex)
{
Console.WriteLine(ex.Message);
StopDAQ();
}
}
RMSvoltages is an Array of doubles used to store the RMS values for each of the 8 channels I want to read. Once again, I am receiving accurate data...however, the refresh time is way too long for my application. I have identified the statement in the code that takes the longest time to execute. The statement, voltageReader.BeginReadWaveform(500,......) is what takes nearly 3 seconds to execute. What can I do to speed up the reading time of the analog waveforms?
Thank you for your assistance.
-Eric
