// delegate
public void RefListCallBack(uint dwCallbackData, uint dwAddr, uint dwVarID, int nData)
 {
    Console.WriteLine("Id=" + dwVarID.ToString() + " Data=" + nData.ToString());
   // dwCallbackData ... will be 2345 (user specified)
   // dwAddr ........... lasalid of changed server
  // dwVarID .......... will be 88 or 99 (user specified)
 // nData ............ changed value (datasize <= 32bit) or crc32 of changed data (datasize > 32bit)
  //... // user has to act on changed value         
        
   }

 private void button1_Click(object sender, RoutedEventArgs e)
        {
           
            Lasal32.CB_RLADD_FUNCTYPE methptr = new Lasal32.CB_RLADD_FUNCTYPE(RefListCallBack);
           // GC.KeepAlive(methptr);
            this.iRlb = Lasal32.LslRefreshListCreateExt("TCP:10.10.150.37;ApplID=10", 0, 0, 0, null, methptr, 2345, 10000);
            if (this.iRlb != 0)
            {
                if (Lasal32.LslRefreshListGetVarInfo(this.iRlb, "Obj_Csharptest1.ListServer", ref this.var1) == true)
                    Lasal32.LslRefreshListAdd(this.iRlb, ref this.var1, 88, 100, Lasal32.CpReflist.RF_DYNAMIC); // add entry to refreshlist
                if (Lasal32.LslRefreshListGetVarInfo(this.iRlb, "Obj_Csharptest1.Position", ref this.var2) == true)
                    Lasal32.LslRefreshListAdd(this.iRlb, ref this.var2, 99, 100, Lasal32.CpReflist.RF_DYNAMIC);  // add entry to refreshlist
                // ... add some more if you want

                Lasal32.LslRefreshListStart(this.iRlb, Lasal32.CpReflist.RF_DYNAMIC); // start refreshlist
                // ... watch outputwindow
               
            }
        }
老师们，请问下 我如何读取RefListCallBack里面的数据呢，每次会弹出“对“OnlineSigmatek!OnlineSigmatek.Lasal32+CB_RLADD_FUNCTYPE::Invoke”类型的已垃圾回收委托进行了回调。这可能会导致应用程序崩溃、损坏和数据丢失。向非托管代码传递委托时，托管应用程序必须让这些委托保持活动状态，直到确信不会再次调用它们。”

public delegate void CB_RLADD_FUNCTYPE(uint pCallbackData, uint dwAddr, uint dwVarID, int nData);
这个是lasal32里面的一个委托。
我在RefListCallBack里面加了这几句
  Id = dwVarID;
  switch (Id)
        {
                case 88:
                    Data1 = nData;
                    break;
                case 99:
                    Data2 = nData;
                    break;
         }
希望能根据不同的ID获得不同的data ，问题就是老是报上面的错误，我是个C#初学者，老师们 ，求解释！！！！

老师们，有知道的吗 很着急 求回复！！！！！

我把完整代码贴上去，求大神指点。。。。。

老师您好，那具体要怎么弄 才能防止委托被回收呢。我设断点测试了，PLC值变化时，c#是有反应的，但是会报错误，委托已回收。求指导。