private void ASyncReadButton_Click(System.Object sender, System.EventArgs e)
{
try
{
_mRequest = null;
_mHandle = 0;
var subscription = OpcController.Subscription;
if (subscription != null)
{
// Begin the asynchronous read request.
if ((subscription.Items != null))
{
StatusBar.Text = "OPC Group Async Read in progress ...";
ReadCompleteEventHandler rceh = OnReadComplete;
subscription.Read(subscription.Items, +_mHandle, rceh, out _mRequest);
}
}
// Update controls if request successful.
if ((_mRequest != null))
{
ASyncReadButton.Enabled = false;
}
}
catch (Exception ex)
{
MessageBox.Show(ex.Message);
}
}
/// <summary>
/// The event handler to recieve the returned results from OPC Server's read acton.
/// </summary>
/// <param name="clientHandle"></param>
/// <param name="results"></param>
private void OnReadComplete(object clientHandle, Opc.Da.ItemValueResult[] results)
{
try
{
if ((object)_mHandle != clientHandle)
{
return;
}
// Save results.
_mRequest = null;
// Check if there is nothing to do.
if (results == null || results.Length == 0)
{
return;
}
WriteControlValues(results);
ASyncReadButton.Enabled = true;
StatusBar.Text = "OPC Group Async Read operation is complete.";
}
catch (Exception e)
{
MessageBox.Show(e.Message);
}
}
private void ASyncWriteButton_Click(System.Object sender, System.EventArgs e)
{
try
{
var subscription = OpcController.Subscription;
var itemsvalue = PrepareControlValueItemList();
// Convert to array of item objects.
_mRequest = null;
_mHandle = 0;
if (subscription != null)
{
// Begin the asynchronous read request.
if (itemsvalue != null)
{
StatusBar.Text = "OPC Group Async Write operation in progress ...";
subscription.Write(itemsvalue, +_mHandle, OnWriteComplete, out _mRequest);
}
}
// Update controls if request successful.
if ((_mRequest != null))
{
ASyncWriteButton.Enabled = false;
}
}
catch (Exception em)
{
MessageBox.Show(em.Message);
}
}
/// <summary>
/// Called when an asynchronous read request completes.
/// </summary>
private void OnReadComplete(object clientHandle, OpcDa::ItemValueResult[] results)
{
try
{
if (InvokeRequired)
{
BeginInvoke(new OpcDa::ReadCompleteEventHandler(OnReadComplete), new object[] { clientHandle, results });
return;
}
if (!m_handle.Equals(clientHandle))
{
return;
}
ResultsCTRL.Initialize(m_subscription.Server, null, results);
m_request = null;
m_results = results;
OkBTN.Enabled = true;
CancelBTN.Enabled = true;
GoBTN.Visible = true;
StopBTN.Visible = false;
}
catch (Exception e)
{
MessageBox.Show(e.Message);
}
}
/// <summary>
/// Begins the asynchronous request.
/// </summary>
private void BeginRequest()
{
try
{
m_request = null;
// begin the asynchronous read request.
if (m_items != null)
{
m_subscription.Read(m_items, ++m_handle, new OpcDa::ReadCompleteEventHandler(OnReadComplete), out m_request);
}
// begin the asynchronous write request.
else if (m_values != null)
{
m_subscription.Write(m_values, ++m_handle, new OpcDa::WriteCompleteEventHandler(OnWriteComplete), out m_request);
}
// update controls if request successful.
if (m_request != null)
{
OkBTN.Enabled = false;
CancelBTN.Enabled = false;
GoBTN.Visible = false;
StopBTN.Visible = true;
}
}
catch (Exception e)
{
MessageBox.Show(e.Message);
}
}
/// <summary>
/// The event handler to recieve the returned results from the Write action.
/// </summary>
/// <param name="clientHandle"></param>
/// <param name="results"></param>
private void OnWriteComplete(object clientHandle, Opc.IdentifiedResult[] results)
{
if (!_mHandle.Equals(clientHandle))
{
return;
}
_mRequest = null;
ASyncWriteButton.Enabled = true;
StatusBar.Text = "OPC Group Async Write operation is complete.";
}
/// <summary>
/// Cancels the asynchronous request.
/// </summary>
private void CancelRequest()
{
try
{
if (m_request != null)
{
m_subscription.Cancel(m_request, new OpcDa::CancelCompleteEventHandler(OnCancelComplete));
}
}
catch (Exception e)
{
m_request = null;
OkBTN.Enabled = true;
CancelBTN.Enabled = true;
GoBTN.Visible = true;
StopBTN.Visible = false;
MessageBox.Show(e.Message);
}
}
/// <summary>
/// Called when an asynchronous write request completes.
/// </summary>
private void OnWriteComplete(object clientHandle, Opc.IdentifiedResult[] results)
{
if (InvokeRequired)
{
BeginInvoke(new OpcDa::WriteCompleteEventHandler(OnWriteComplete), new object[] { clientHandle, results });
return;
}
if (!m_handle.Equals(clientHandle))
{
return;
}
ResultsCTRL.Initialize(m_subscription.Server, null, results);
m_request = null;
m_results = results;
OkBTN.Enabled = true;
CancelBTN.Enabled = true;
GoBTN.Visible = true;
StopBTN.Visible = false;
}
