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RMCLink.Interop .NET Assembly RMCLink.CancelRequest Method |
This method can be used in multi-threaded applications to cancel the currently-in-progress read, write, or connect request.
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Visual Basic (Declaration) |
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Public Sub CancelRequest |
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Visual Basic (Usage) |
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Dim instance As RMCLink
instance.CancelRequest() |
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C# |
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public void CancelRequest () |
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Visual C++/CLI |
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public: void CancelRequest () |
This method is only for use in multi-threaded applications.
This method signals the current read, write, or connection attempt (if one is in progress) to throw a CancelledException, and then returns immediately. Notice that the CancelledException may be thrown on the transaction's thread before or after this method returns on its thread. If no transaction is in progress when this method is called, then this method will do nothing and return.
This method affects, at most, one transaction (read, write, or connection attempt), so requests made after this method returns will behave normally.
No exceptions are generated by this method.
The following code example illustrates the use of the CancelRequest method.
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Visual Basic |
Imports RMCLinkNET
Imports System.Threading
' Assumes that the form contains the following controls:
' buttonRead - Button labeled "Read Position".
' buttonCancel - Button labeled "Cancel" (defaults disabled).
' textBoxActPos - Read-only TextBox that displays Axis 0 Actual Position.
' textBoxStatus - Read-only TextBox that displays results of the read.
Public Class TestForm
Private Sub buttonRead_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles buttonRead.Click
If (Not isReadInProgress) Then
myRmc = RMCLink.CreateEthernetLink(DeviceType.RMC70, "192.168.0.10")
isReadInProgress = True
' Disable the Read button and enable the Cancel button.
buttonRead.Enabled = False
buttonCancel.Enabled = True
' Start the Thread that will do the read.
Dim worker As Thread = New Thread(New ThreadStart(AddressOf doUpdate))
worker.Name = "Worker"
worker.Start()
End If
End Sub
Private Sub buttonCancel_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles buttonRead.Click
If (isReadInProgress) Then
If (Not myRmc Is Nothing) Then
myRmc.CancelRequest()
End If
End If
End Sub
Private Sub doUpdate()
Try
Try
textBoxStatus.Text = "Connecting..."
myRmc.Connect()
Try
Dim data() As Single = New Single(0) {}
textBoxStatus.Text = "Reading..."
myRmc.ReadFFile(FileNumber70.fn70StatusAxis0, 8, data, 0, 1)
textBoxActPos.Text = String.Format("{0:F3}", data(0))
textBoxStatus.Text = "Read successful."
Finally
myRmc.Disconnect()
End Try
Catch ex As ConnectionNotMadeException
textBoxStatus.Text = "Unable to connect."
MessageBox.Show("Unable to connect to the controller. " + ex.Message)
Catch ex As ReadWriteFailedException
textBoxStatus.Text = "Read failed."
MessageBox.Show("Unable to read from the controller. " + ex.Message)
Catch ex As CancelledException
textBoxStatus.Text = "Read Cancelled."
End Try
Finally
isReadInProgress = False
buttonRead.Enabled = True
buttonCancel.Enabled = False
End Try
End Sub
Private myRmc As RMCLink = Nothing
Private isReadInProgress As Boolean = False
End Class
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C# |
using System;
using System.Windows.Forms;
using System.Threading;
using RMCLinkNET;
// Assumes that the form contains the following controls:
// buttonRead - Button labeled "Read Position".
// buttonCancel - Button labeled "Cancel" (defaults disabled).
// textBoxActPos - Read-only TextBox that displays Axis 0 Actual Position.
// textBoxStatus - Read-only TextBox that displays results of the read.
namespace Example
{
public partial class TestForm : Form
{
...
private void buttonRead_Click(object sender, EventArgs e)
{
if ( ! isReadInProgress)
{
myRmc = RMCLink.CreateEthernetLink(DeviceType.RMC70, "192.168.0.10");
isReadInProgress = true;
// Disable the Read button and enable the Cancel button.
buttonRead.Enabled = false;
buttonCancel.Enabled = true;
// Start the Thread that will do the read.
Thread worker = new Thread(new ThreadStart(doUpdate));
worker.Name = "Worker";
worker.Start();
}
}
private void buttonCancel_Click(object sender, EventArgs e)
{
if (isReadInProgress)
{
if (myRmc != null)
myRmc.CancelRequest();
}
}
private void doUpdate()
{
try
{
try
{
textBoxStatus.Text = "Connecting...";
myRmc.Connect();
try
{
float[] data = new float[1];
textBoxStatus.Text = "Reading...";
myRmc.ReadFFile((int)FileNumber70.fn70StatusAxis0, 8, data, 0, 1);
textBoxActPos.Text = String.Format("{0:F3}", data[0]);
textBoxStatus.Text = "Read successful.";
}
finally
{
myRmc.Disconnect();
}
}
catch (ConnectionNotMadeException e)
{
textBoxStatus.Text = "Unable to connect.";
MessageBox.Show("Unable to connect to the controller. " + e.Message);
}
catch (ReadWriteFailedException e)
{
textBoxStatus.Text = "Read failed.";
MessageBox.Show("Unable to read from the controller. " + e.Message);
}
catch (CancelledException)
{
textBoxStatus.Text = "Read Cancelled.";
}
}
finally
{
isReadInProgress = false;
buttonRead.Enabled = true;
buttonCancel.Enabled = false;
}
}
private RMCLink myRmc = null;
private bool isReadInProgress = false;
}
}
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Visual C++/CLI |
namespace RMCLinkNETVCPPSampleUI
{
using namespace System;
using namespace System::ComponentModel;
using namespace System::Windows::Forms;
using namespace System::Threading;
using namespace RMCLinkNET;
// Assumes that the form contains the following controls:
// buttonRead - Button labeled "Read Position".
// buttonCancel - Button labeled "Cancel" (defaults disabled).
// textBoxActPos - Read-only TextBox that displays Axis 0 Actual Position.
// textBoxStatus - Read-only TextBox that displays results of the read.
public ref class Form1 : public System::Windows::Forms::Form
{
public:
Form1(void) : myRmc(nullptr), isReadInProgress(false)
{
InitializeComponent();
}
...
private:
System::Void buttonRead_Click(System::Object^ sender, System::EventArgs^ e)
{
if ( ! isReadInProgress)
{
myRmc = RMCLink::CreateEthernetLink(DeviceType::RMC70, "192.168.0.10");
isReadInProgress = true;
// Disable the Read button and enable the Cancel button.
buttonRead->Enabled = false;
buttonCancel->Enabled = true;
// Start a Thread to do the work.
Thread^ worker = gcnew Thread(gcnew ThreadStart(this, &Form1::doUpdate));
worker->Name = "Worker";
worker->Start();
}
}
System::Void buttonCancel_Click(System::Object^ sender, System::EventArgs^ e)
{
if (isReadInProgress)
{
if (myRmc != nullptr)
myRmc->CancelRequest();
}
}
System::Void doUpdate(System::Void)
{
try
{
try
{
textBoxStatus->Text = "Connecting...";
myRmc->Connect();
try
{
array<float>^ data = gcnew array<float>(1);
textBoxStatus->Text = "Reading...";
myRmc->ReadFFile((int)FileNumber70::fn70StatusAxis0, 8, data, 0, 1);
textBoxActPos->Text = String::Format("{0:F3}", data[0]);
textBoxStatus->Text = "Read successful.";
}
finally
{
myRmc->Disconnect();
}
}
catch (ConnectionNotMadeException^ e)
{
textBoxStatus->Text = "Unable to connect.";
MessageBox::Show("Unable to connect to the controller. " + e->Message);
}
catch (ReadWriteFailedException^ e)
{
textBoxStatus->Text = "Read failed.";
MessageBox::Show("Unable to read from the controller. " + e->Message);
}
catch (CancelledException^)
{
textBoxStatus->Text = "Read Cancelled.";
}
}
finally
{
isReadInProgress = false;
buttonRead->Enabled = true;
buttonCancel->Enabled = false;
}
}
RMCLink^ myRmc;
bool isReadInProgress;
};
}
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See Also
RMCLink.Interop .NET Assembly | RMCLinkNET Namespace | RMCLink Class
Copyright (c) 2024 Delta Computer Systems, Inc. dba Delta Motion