I have uploaded my full code that I use for testing this (see below). This is close to the simplest set of commands for replicating this issue.
Additionally is there a reason why you say that you don't think there's a bug? I would be more than happy to find out that you are correct, but I am wondering if you have information.
Thanks for the link on synchronising analog and digital, but as you can see that is not something which I am doing in this case (and whether I do it or not does not effect this bug).
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using NationalInstruments.DAQmx;
using System.Diagnostics;
using System.Threading;
// This class is a toy example intended to replicate the issue where queueing of data on the daq gets slower over time (if the timing is being changed)
namespace DaqQueueTimingIncreaseTestExample
{
class Program
{
static void Main(string[] args)
{
//change these values as desired for testing on another machine
string[] AnalogOutputChannels = new string[] { "cDAQ1Mod2/ao0" };
string[] DigitalOutputChannels = new string[] { "cDAQ1Mod3/Port0/line0"};
string outputFileLocation = "C:\\Users\\Q-State Admin\\Documents\\Adam\\daqTiming.txt"; //this is a file where the timing information will be saved
//These values exist for experimenting with using them to get around the issue
string masterClock = "";
string analogClock = "";
// Setup values:
int signalNumber = 50;
int numberOfRuns = 50;
double daqRate = 7893.846153846154;
Task analogOutputTask = new Task();
AnalogMultiChannelWriter analogWriter = new AnalogMultiChannelWriter(analogOutputTask.Stream);
Task digitalOutputTask = new Task();
DigitalMultiChannelWriter digitalWriter = new DigitalMultiChannelWriter(digitalOutputTask.Stream);
Stopwatch timer = new Stopwatch();
long[] bigQueueTimings = new long[numberOfRuns];
long[] smallQueueTimings = new long[numberOfRuns];
// Build the daq and connections and make data
for (int i=0; i < AnalogOutputChannels.Length; i++)
{
analogOutputTask.AOChannels.CreateVoltageChannel(AnalogOutputChannels[i],
"", -10.0, 10.0, AOVoltageUnits.Volts);
}
for(int i=0; i < DigitalOutputChannels.Length; i++)
{
digitalOutputTask.DOChannels.CreateChannel(DigitalOutputChannels[i],
"", ChannelLineGrouping.OneChannelForEachLine);
}
analogOutputTask.Control(TaskAction.Verify);
digitalOutputTask.Control(TaskAction.Verify);
int[,] digitalSignals = new int[DigitalOutputChannels.Length, signalNumber];
int[,] smallerDigitalSignals = new int[DigitalOutputChannels.Length, 2];
double[,] analogSignals = new double[AnalogOutputChannels.Length, signalNumber];
double[,] smallerAnalogSignals = new double[AnalogOutputChannels.Length, 2];
// Setting up initial timing
analogOutputTask.Timing.ConfigureSampleClock(masterClock, daqRate,
SampleClockActiveEdge.Rising, SampleQuantityMode.FiniteSamples, 100);
digitalOutputTask.Timing.SampleTimingType = SampleTimingType.SampleClock;
digitalOutputTask.Timing.ConfigureSampleClock(analogClock, daqRate,
SampleClockActiveEdge.Rising, SampleQuantityMode.FiniteSamples, 100);
// performing runs
for (int runCounter = 0; runCounter < numberOfRuns; runCounter++)
{
//setup first timing
timer.Reset();
analogOutputTask.Timing.SamplesPerChannel = analogSignals.Length;
digitalOutputTask.Timing.SamplesPerChannel = digitalSignals.Length;
timer.Start();
digitalWriter.WriteMultiSamplePort(false, digitalSignals);
analogWriter.WriteMultiSample(false, analogSignals);
timer.Stop();
bigQueueTimings[runCounter] = timer.ElapsedMilliseconds;
Console.WriteLine(bigQueueTimings[runCounter].ToString());
// run out those signals
digitalOutputTask.Start();
analogOutputTask.Start();
while(!analogOutputTask.IsDone || !digitalOutputTask.IsDone)
{
System.Threading.Thread.Sleep(2);
}
digitalOutputTask.Stop();
analogOutputTask.Stop();
//setup second timing
timer.Reset();
analogOutputTask.Timing.SamplesPerChannel = smallerAnalogSignals.Length;
digitalOutputTask.Timing.SamplesPerChannel = smallerDigitalSignals.Length;
timer.Start();
digitalWriter.WriteMultiSamplePort(false, smallerDigitalSignals);
analogWriter.WriteMultiSample(false, smallerAnalogSignals);
timer.Stop();
smallQueueTimings[runCounter] = timer.ElapsedMilliseconds;
Console.WriteLine(smallQueueTimings[runCounter].ToString());
// run out those signals
digitalOutputTask.Start();
analogOutputTask.Start();
while (!analogOutputTask.IsDone || !digitalOutputTask.IsDone)
{
System.Threading.Thread.Sleep(2);
}
digitalOutputTask.Stop();
analogOutputTask.Stop();
}
// record data
using (System.IO.StreamWriter file =
new System.IO.StreamWriter(@outputFileLocation))
{
file.WriteLine("Small Queue Timings:");
file.Write("[");
foreach(int time in smallQueueTimings)
{
file.Write(time.ToString() + ", ");
}
file.WriteLine("]");
file.WriteLine("Big Queue Timings:");
file.Write("[");
foreach (int time in bigQueueTimings)
{
file.Write(time.ToString() + ", ");
}
file.Write("]");
}
}
}
}
