高级HMI订阅具有指向m_SynchronizingObject的空指针。

Question

我在尝试订阅时出错了。m_Plc.Read函数工作得很好，但对我的应用程序来说太慢了。

这是我的密码：

private AdvancedHMIDrivers.EthernetIPforCLXCom m_Plc;
public MainPageViewModel()
{
   m_Plc = new EthernetIPforCLXCom();
   m_Plc.IPAddress = m_IPAddress;
   m_Plc.ProcessorSlot = Convert.ToInt32(m_ProcessorSlot);
   m_Plc.ComError += DoOnCommError;
   m_Plc.SubscriptionError += DoOnCommError;
   string testString = m_Plc.Read("MyTag");  
   int index = m_Plc.Subscribe("MyTag", 1, 2000, testPlcReaded);
}
private void testPlcReaded(object sender, MfgControl.AdvancedHMI.Drivers.Common.PlcComEventArgs e)
{
    try
    {
        Console.WriteLine(e.Values[0]);
    }
    catch (Exception ex)
    {
        Console.WriteLine(ex);
    }
}

这就是我所犯的错误：

( m_SynchronizingObject.BeginInvoke(SubscriptionList(i).dlgCallBack，z)

它在文件夹中: EthernetIPforCLXCom.vb。

有一个指向m_SynchronizingObject的空指针.

错误-详细信息：

System.NullReferenceException was unhandled by user code
  HResult=-2147467261
  Message=Object reference not set to an instance of an object.
  Source=AdvancedHMIDrivers
  StackTrace:
       at AdvancedHMIDrivers.EthernetIPforCLXCom.DataLinkLayer_DataReceived(Object sender, PlcComEventArgs e) in C:\prj\TLLAB\TLLAB\AdvancedHMIBeta363 (1)\AdvancedHMIDrivers\EthernetIPforCLXCom.vb:line 1269
       at MfgControl.AdvancedHMI.Drivers.CIP.OnDataReceived(PlcComEventArgs e)
       at MfgControl.AdvancedHMI.Drivers.CIP.DataReceivedEIP(Object sender, PlcComEventArgs e)

Answer 1

在我看来，在当前版本中，这是一个bug。

代码检查SynchronizingObject是否为空，或者在调用它之前是否创建了它的句柄，所以如果它是空的，它就会崩溃。

If m_SynchronizingObject Is Nothing OrElse DirectCast(m_SynchronizingObject, Windows.Forms.Control).IsHandleCreated Then
    '...<some code>...

    m_SynchronizingObject.BeginInvoke(SubscriptionList(i).dlgCallBack, z)
End If

您应该提交一个bug，因为它可能应该如下所示

If m_SynchronizingObject IsNot Nothing AndAlso DirectCast(m_SynchronizingObject, Windows.Forms.Control).IsHandleCreated Then
    '...<some code>...

    m_SynchronizingObject.BeginInvoke(SubscriptionList(i).dlgCallBack, z)
Else
    '...<some other code>...
End If

编辑:我把这个发给了Sourceforge的项目现场，阿奇已经解决了下一个版本的问题

Answer 2

您没有实例化对象。当您尝试使用它时，它是空的。这应有助于：

private EthernetIPforCLXCom m_Plc = new EthernetIPforCLXCom
 {
   IPAddress = m_IPAddress,
   ProcessorSlot = Convert.ToInt32(m_ProcessorSlot),
   ComError += DoOnCommError,
   SubscriptionError += DoOnCommError
};