Hi,
I used NI USB 6221 DAQ board and EM1 optical encoder from US Digital.
By wrong values I mean wrong positioning from 10 and less degrees. from 10 degrees and above my arm rotated correctly.
I connected the same optical encoder on this card, in the same way, but for linear motion and works perfectly (I tested it using digital caliper).
Actually, I translate the edgecounter value coming from the card to degrees by using the following formula:
edgecount = ((2500 * (degress)) / 360)
I used the following C Shapr function to get the edgecounter value
private void getEdgeCounterValuethita(int maxvaluethita, int direction)
{
Cursor.Current = Cursors.WaitCursor;
try//try block for catching unnecessary errors
{
using (Task CounterReadTask = new Task())//create new Task and using it
{
deviceid = cmbdeviceid.Text;//store the selected the dev ID
//create a counter read task by adding the parameters to the counter input channel
CounterReadTask.CIChannels.CreateCountEdgesChannel(deviceid + "/ctr1",
"", edgeType, Convert.ToInt64("0"), countDirection);//counter type and direction
//set timing parameters to the counter reader task
CounterReadTask.Timing.ConfigureSampleClock(deviceid + "/PFI3",
Convert.ToDouble("100000.00"), SampleClockActiveEdge.Rising,
SampleQuantityMode.FiniteSamples, Convert.ToInt32("100000"));
runningTask = CounterReadTask;
//create an instance of the counter reader configure above
myCounterReader = new CounterReader(CounterReadTask.Stream);
//initialize the variables to zero each time to call the function
double data = 0;
int currposition = 0;
while (data < maxvaluethita)//compare curreent value with requir value
{
data = myCounterReader.ReadSingleSampleInt32();//getting an integer number of lines read so far during the motion
}
stopmotors();//stop the current motion
//if block statement for desiding the correct direction of the motion and update the interface
//1 for cw and 0 for ccw
if (direction == 1)
{
//data = (360 * (data + 30))/2500;//convert the edgacount back to degrees
currposition = Convert.ToInt32(txtthitaposition.Text) + Convert.ToInt32 (txtthitacw.Text);//calculate the current position
txtthitaposition.Text = currposition.ToString();//store the current postion to the text box control
addCommandToHistoryList("ClockWise rotation on Θ Axis " + txtthitacw.Text + " degress, ");
}
else
{
//data = (360 * (data + 30)) / 2500;//convert the edgacount back to degrees
currposition = Convert.ToInt32(txtthitaposition.Text) - Convert.ToInt32(txtthitaccw.Text);//calculate the current position
txtthitaposition.Text = Convert.ToString(currposition);//store the current position to the text box control
addCommandToHistoryList("Counter ClockWise rotation on Θ Axis " + txtthitaccw.Text + " degress, ");
}
}
}
catch (DaqException ex)//catch any errors during the execution of the try block
{
MessageBox.Show(ex.Message);//message after catching an error
}
finally
{
Cursor.Current = Cursors.Default;
}
}
