public static void MyCallback(int bd, MccDaq.EventType et, uint sampleCount, IntPtr pUserData)
{
//MyCallback is a static member function. So, we must do some work to get the reference
// to this object. Recall that we passed in a pointer to a struct that wrapped the
// class reference as UserData.
TUserData userStruct = (TUserData)Marshal.PtrToStructure(pUserData, typeof(TUserData));
frmEventDisplay ThisObj = (frmEventDisplay)userStruct.ThisObj;
//Calculate the index of the latest sample in the buffer.
int sampleIdx = ((int)sampleCount - 1) % ThisObj.TotalCount;
ushort[] rawData = new ushort[1];
uint[] rawData32 = new uint[1];
float voltData;
double highResVoltData;
ThisObj.lblSampleCount.Text = sampleCount.ToString();
//Retrieve the latest sample and convert it to engineering units.
if (ThisObj.ADResolution > 16)
{
MccDaq.MccService.WinBufToArray32(ThisObj.MemHandle, rawData32, (int)sampleIdx, 1);
ThisObj.DaqBoard.ToEngUnits32(ThisObj.Range, rawData32[0], out highResVoltData);
ThisObj.lblLatestSample.Text = highResVoltData.ToString("F5") + " V";
}
else
{
MccDaq.MccService.WinBufToArray(ThisObj.MemHandle, rawData, (int)sampleIdx, 1);
ThisObj.DaqBoard.ToEngUnits(ThisObj.Range, rawData[0], out voltData);
ThisObj.lblLatestSample.Text = voltData.ToString("F4") + " V";
}
if (et == MccDaq.EventType.OnEndOfAiScan)
{
// If the event is the end of acquisition, release the
// resources in preparation for the next scan.
ThisObj.DaqBoard.StopBackground(MccDaq.FunctionType.AiFunction);
if (ThisObj.chkAutoRestart.Checked)
{
int rate = ThisObj.DesiredRate;
ThisObj.DaqBoard.AInScan(0, 0, ThisObj.TotalCount, ref rate,
ThisObj.Range, ThisObj.MemHandle, ThisObj.Options);
}
else
{
ThisObj.lblStatus.Text = "IDLE";
ThisObj.cmdStart.Enabled = true;
}
}
}
private void cmdEnableEvent_Click(object sender, System.EventArgs e)
{
/// Enable and connect one or more event types to a single user callback
/// function using MccDaq.MccBoard.EnableEvent().
///
/// If we want to attach a single callback function to more than one event
/// type, we can do it in a single call to MccDaq.MccBoard.EnableEvent, or we can do this in
/// separate calls for each event type. The main disadvantage of doing this in a
/// single call is that if the call generates an error, we will not know which
/// event type caused the error. In addition, the same error condition could
/// generate multiple error messages.
///
/// Parameters:
/// eventType :the condition that will cause an event to fire
/// eventSize :only used for MccDaq.EventType.OnDataAvailable to determine how
/// many samples to collect before firing an event
/// _ptrMyCallback : a pointer to the user function or event handler
/// to call when above event type occurs. Note that the handler
/// can be a delegate or a static member function. Here, we use
/// a pointer to a static member function.
///
/// _ptrUserData : a pointer to a value type that will be used within the event
/// handler. Since our handler is a static member function which
/// does NOT include a reference to this class instance, we're
/// sending the pointer to a struct that holds a reference to the class.
uint eventSize = 0;
MccDaq.EventType eventType = MccDaq.EventType.OnEndOfAiScan;
MccDaq.ErrorInfo ULStat =
DaqBoard.EnableEvent(eventType, eventSize, _ptrMyCallback, _ptrUserData);
bool ValidEntry = uint.TryParse(txtEventSize.Text, out eventSize);
eventType = MccDaq.EventType.OnDataAvailable;
if (ValidEntry)
{
ULStat = DaqBoard.EnableEvent
(eventType, eventSize, _ptrMyCallback, _ptrUserData);
}
else
{
ULStat = DaqBoard.DisableEvent(eventType);
}
eventType = MccDaq.EventType.OnScanError;
ULStat = DaqBoard.EnableEvent(eventType, 0, _ptrOnScanError, _ptrUserData);
cmdEnableEvent.Enabled = false;
}
public static void OnScanError(int bd, MccDaq.EventType et, uint scanError, IntPtr pdata)
{
//OnScanError is a static member function. So, we must do some work to get the reference
// to this object. Recall that we passed in a pointer to a struct that wrapped the
// class reference as UserData...
TUserData thisStruct = (TUserData)Marshal.PtrToStructure(pdata, typeof(TUserData));
frmEventDisplay ThisObj = (frmEventDisplay)thisStruct.ThisObj;
ThisObj.DaqBoard.StopBackground(MccDaq.FunctionType.AiFunction);
// Reset the chkAutoRestart such that the 'OnEndOfAiScan' event does
//not automatically start a new scan
ThisObj.chkAutoRestart.Checked = false;
}
