OPC客户端的自动化实现

                                                        OPC客户端的自动化实现

OPC是建立在COM，DCOM的基础商的，因此绝大多数语言都可以很好的进行开发。在Net中开发客户端有以下几种方式：

（1）       使用OPCNetAPI，需要用到OPCNetAPI.dll，OPCNetAPI.Com.dll

（2）       使用自动化接口，需要用到OPCDAAuto.dll

（3）       使用自定义接口，需要用到多个Wrapper：OpcRcw.Ae.dll，OpcRcw.Batch.dll，OpcRcw.Comn.dll，OpcRcw.Da.dll，OpcRcw.Dx.dll，OpcRcw.Hda.dll，OpcRcw.Sec.dll

以上开发方式所需的动态链接库可以从OPC基金会（http://www.opcfoundation.org/）的网站上下载，一些下载项目可能需要注册，或成为基金会的成员。

不同的方式有各自的有缺点，请参见…

本文使用自动化接口，VB.Net语言进行开发，开发项目是无线射频（RFID）卡方面的应用，典型的如公交车，或公司考勤使用的刷卡机。需要注意的是自动化接口存在一个“不是问题”的问题，数组下标是以1开始的，而不是传统计算机开发上的以0开始。不知道设计者头脑是怎么想（有人知道吗？）；这可能会给一些语言的开发造成问题（有人碰到吗，没有你就是幸运的）

需求：OPCDAAuto.dll或该Dll的Interop

(一)  ：客户端开发流程

OPC客户端的开发主要遵循下图所示的开发流程，下面就从以下几个开发步骤进行说明
 

(二)  ：枚举OPC服务器列表

枚举服务器主要是通过OPCServer接口的GetOPCServers方法来实现的，该方法会返回OPC服务器数组（以1为下界，上面已有说明），以下是代码段

    '枚举OPC服务器列表

    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load

        Try

            GlobalOPCServer = New OPCAutomation.OPCServerClass()

            Dim ServerList As Object = GlobalOPCServer.GetOPCServers

            For index As Short = LBound(ServerList) To UBound(ServerList) '加入控件列表中，注意这里使用LBound和UBound

                cbbServerList.Items.Add(ServerList(index))

            Next

            If cbbServerList.Items.Count > 0 Then

                cbbServerList.SelectedIndex = 0

            End If

            ResetControlStatus() '设置控件状态

            GlobalOPCServer = Nothing

        Catch Ex As Exception

            MessageBox.Show("List OPC servers failed: " + Ex.Message, "OPCSample", MessageBoxButtons.OK)

        End Try

End Sub

(三)  ：连接OPC服务器

自动化接口中连接到服务器是使用connect方法

Public Overridable Sub Connect(ByVal ProgID As String, Optional ByVal Node As Object = Nothing)

ProgID指服务器的ProgID，Node代表网络节点，如果是本机则放空即可。

连接到服务器后，以下属性需要特别注意：

OPCServer.StartTime：服务器的启动时间

OPCServer.CurrentTime：服务器的当前时间，各个客户端可以通过这个属性值完成一些同步的操作

OPCGroups.DefaultGroupIsActive：以后添加的Group是否默认激活

OPCGroups.DefaultGroupDeadBand：Group的默认死区，变化量超过死区后将会触发DataChange事件，

合理的设置该值可以提高程序性能

OPCGroups.Count：下属组（Group）的数量

OPCGroups.DefaultGroupLocalID：组（Group）的默认通信区域编号，如1024

OPCGroups.DefaultGroupUpdateRate：组（Group）的默认刷新率，该属性也比较重要

OPCGroups.DefaultGroupTimeBias：组（Group）的默认时间偏差

(四)  ：添加组（Group）和项 （Item）

添加组和项需要用到Groups.Add和Items.AddItem方法，以下是原型：

Function Add(Optional ByVal Name As Object = Nothing) As OPCAutomation.OPCGroup

Function AddItem(ByVal ItemID As String, ByVal ClientHandle As Integer) As OPCAutomation.OPCItem

       组也有两个重要的属性

       Group.UpdateRate：刷新率，该属性通Groups的UpdateRate意义一样，如果这个值有设置，则以这个值为准

       Group. IsSubscribed：是否使用订阅功能

     以下是代码段

         '连接到指定的OPC服务器

    Private Sub btnConnectServer_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnConnectServer.Click

        If cbbServerList.Text <> "" Then

            ConnectedOPCServer = New OPCAutomation.OPCServerClass()

            Try

                ConnectedOPCServer.Connect(cbbServerList.Text)

                '设置组集合的默认属性

                ConnectedOPCServer.OPCGroups.DefaultGroupIsActive = True

                ConnectedOPCServer.OPCGroups.DefaultGroupDeadband = 0

                '添加组

                ConnectedGroup = ConnectedOPCServer.OPCGroups.Add()

                ConnectedGroup.UpdateRate = 3 * 1000 '刷新虑，用于下面的DataChange事件

                ConnectedGroup.IsSubscribed = True '使用订阅功能

                '添加项

                GlobalOPCItems(0) = ConnectedGroup.OPCItems.AddItem("Reader_Device.OpenCard", 0)

                GlobalOPCItems(1) = ConnectedGroup.OPCItems.AddItem("Reader_Device.CloseCard", 1)

                GlobalOPCItems(2) = ConnectedGroup.OPCItems.AddItem("Reader_Device.CardNO", 2)

                RefreshServerStatus() '刷新服务器状态

            Catch ex As Exception

                ConnectedOPCServer = Nothing

                MessageBox.Show("OPC server connect failed : " + ex.Message, "OPCSample", MessageBoxButtons.OK)

            End Try

            ResetControlStatus()

        End If

    End Sub

(五)  ：读写操作与事件控制

读写操作包括同步和异步两种操作方式，以下是这几个方法的原型：

Group的同步读事件

Sub SyncRead(ByVal Source As Short, ByVal NumItems As Integer, ByRef ServerHandles As System.Array, ByRef Values As System.Array, ByRef Errors As System.Array, Optional ByRef Qualities As Object = Nothing, Optional ByRef TimeStamps As Object = Nothing)

 

Group的同步写事件

Sub SyncWrite(ByVal NumItems As Integer, ByRef ServerHandles As System.Array, ByRef Values As System.Array, ByRef Errors As System.Array)

 

Group的异步读事件

Sub AsyncRead(ByVal NumItems As Integer, ByRef ServerHandles As System.Array, ByRef Errors As System.Array, ByVal TransactionID As Integer, ByRef CancelID As Integer)

 

Group的异步写事件

Sub AsyncWrite(ByVal NumItems As Integer, ByRef ServerHandles As System.Array, ByRef Values As System.Array, ByRef Errors As System.Array, ByVal TransactionID As Integer, ByRef CancelID As Integer)

如果使用异步的读写操作，那么还需要实现Group中的ReadComplete和WriteComplete两个事件

Public Event AsyncReadComplete(ByVal TransactionID As Integer, ByVal NumItems As Integer, ByRef ClientHandles As System.Array, ByRef ItemValues As System.Array, ByRef Qualities As System.Array, ByRef TimeStamps As System.Array, ByRef Errors As System.Array)

 

Public Event AsyncWriteComplete(ByVal TransactionID As Integer, ByVal NumItems As Integer, ByRef ClientHandles As System.Array, ByRef Errors As System.Array)

其他相关的重要事件包括：

Group数据变化时的通知事件

Public Event DataChange(ByVal TransactionID As Integer, ByVal NumItems As Integer, ByRef ClientHandles As System.Array, ByRef ItemValues As System.Array, ByRef Qualities As System.Array, ByRef TimeStamps As System.Array)

 

Group的异步取消事件

Public Event AsyncCancelComplete(ByVal CancelID As Integer)

 

Server（服务器）关闭通知事件

Public Event ServerShutDown(ByVal Reason As String)

 

以下是这些实现的代码段

    '读取卡片指定的块号的值

    Private Sub btnReadCard_Click(ByVal sender As System.Object, ByVal e As System.EventArgs)

        If Not (ConnectedGroup Is Nothing) Then

            Try

                '获取块号

                Dim BlockNo As Short = CByte(ReadBlockNo.Text)

                '如果要获取数据的块所对应的项还没有创建，就创建它

                If GlobalOPCBlockItems(BlockNo) Is Nothing Then

                    GlobalOPCBlockItems(BlockNo) = ConnectedGroup.OPCItems.AddItem("Reader_Device.Block" & CStr(BlockNo), 200 + BlockNo)

                End If

                '准备参数数组

                Dim ServerResults As System.Array

                Dim ServerErrors As System.Array

                Dim ServerHandles(1) As Integer

                ServerHandles(1) = GlobalOPCBlockItems(BlockNo).ServerHandle

                '读取值

                ConnectedGroup.SyncRead(OPCAutomation.OPCDataSource.OPCDevice, 1, ServerHandles, ServerResults, ServerErrors)

                If ServerErrors(1) <> 0 Then

                    MsgBox("Read Card Failed:" & ServerErrors(1))

                Else

                    txtReadBlockNo.Text = ServerResults(1)

                End If

            Catch ex As Exception

                MessageBox.Show("OPC server Read Card failed: " + ex.Message, "OPCSample", MessageBoxButtons.OK)

            End Try

        End If

End Sub

 

    '写卡片指定块的值

    Private Sub btnWriteCard_Click(ByVal sender As System.Object, ByVal e As System.EventArgs)

        If Not (ConnectedGroup Is Nothing) Then

            Try

                '获取块号

                Dim BlockNo As Short = CByte(WriteBlockNo.Text)

                '如果要写入数据的块所对应的项还没有创建，就创建它

                If GlobalOPCBlockItems(BlockNo) Is Nothing Then

                    GlobalOPCBlockItems(BlockNo) = ConnectedGroup.OPCItems.AddItem("Reader_Device.Block" & CStr(BlockNo), 200 + BlockNo)

                End If

                '准备参数数组

                Dim ServerValues(1) As Object

                Dim ServerErrors As Array

                Dim ServerHandles(1) As Integer

                ServerHandles(1) = GlobalOPCBlockItems(BlockNo).ServerHandle

                ServerValues(1) = txtWriteBlockNo.Text

                '写入值

                ConnectedGroup.SyncWrite(1, ServerHandles, ServerValues, ServerErrors)

                If ServerErrors(1) <> 0 Then

                    MsgBox("Write Card Failed:" & ServerErrors(1))

                Else

                    MsgBox("Write Card Succeed")

                End If

            Catch ex As Exception

                MessageBox.Show("OPC server Write Card failed: " + ex.Message, "OPCSample", MessageBoxButtons.OK)

            End Try

        End If

End Sub

(六)  ：断开服务器

断开服务器只要使用OPCServer的Disconnect方法几个，以下是代码段：

    '断开到指定OPC服务器的连接

    Private Sub btnDisconnectServer_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnDisconnectServer.Click

        If Not (ConnectedOPCServer Is Nothing) Then

            Try

                ConnectedOPCServer.Disconnect()

            Catch ex As Exception

                MessageBox.Show("OPC server disconnect failed: " + ex.Message, "OPCSample", MessageBoxButtons.OK)

            Finally

                ConnectedOPCServer = Nothing

                ResetControlStatus()

            End Try

        End If

End Sub

(七)  ：相关链接

非常好的一个OPC技术网站http://www.opcconnect.com/

OPC基金会网址http://www.opcfoundation.org/

国内的一个比较好的OPC网站http://www.opc-china.com/Index.html

(八)：全部源码

  1 Imports  System.Runtime.InteropServices
  2 Public   Class Form1 Class Form1
  3
  4    Dim GlobalOPCServer As OPCAutomation.OPCServerClass
  5    Dim WithEvents ConnectedOPCServer As OPCAutomation.OPCServerClass
  6    Dim WithEvents ConnectedGroup As OPCAutomation.OPCGroupClass
  7
  8    Dim GlobalOPCItems(4) As OPCAutomation.OPCItem
  9    Dim GlobalOPCBlockItems(64) As OPCAutomation.OPCItem
 10
 11
 12    '枚举OPC服务器列表
 13    Private Sub Form1_Load()Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
 14        Try
 15            GlobalOPCServer = New OPCAutomation.OPCServerClass()
 16            Dim ServerList As Object = GlobalOPCServer.GetOPCServers
 17            For index As Short = LBound(ServerList) To UBound(ServerList) '加入控件列表中，注意这里使用LBound和UBound
 18                cbbServerList.Items.Add(ServerList(index))
 19            Next
 20            If cbbServerList.Items.Count > 0 Then
 21                cbbServerList.SelectedIndex = 0
 22            End If
 23            ResetControlStatus() '设置控件状态
 24            GlobalOPCServer = Nothing
 25        Catch Ex As Exception
 26            MessageBox.Show("List OPC servers failed: " + Ex.Message, "OPCSample", MessageBoxButtons.OK)
 27        End Try
 28    End Sub
 29
 30    '连接到指定的OPC服务器
 31    Private Sub btnConnectServer_Click()Sub btnConnectServer_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnConnectServer.Click
 32        If cbbServerList.Text <> "" Then
 33            ConnectedOPCServer = New OPCAutomation.OPCServerClass()
 34            Try
 35                ConnectedOPCServer.Connect(cbbServerList.Text)
 36                '设置组集合的默认属性
 37                ConnectedOPCServer.OPCGroups.DefaultGroupIsActive = True
 38                ConnectedOPCServer.OPCGroups.DefaultGroupDeadband = 0
 39                '添加组
 40                ConnectedGroup = ConnectedOPCServer.OPCGroups.Add()
 41                ConnectedGroup.UpdateRate = 3 * 1000 '刷新虑，用于下面的DataChange事件
 42                ConnectedGroup.IsSubscribed = True '使用订阅功能
 43                '添加项
 44                GlobalOPCItems(0) = ConnectedGroup.OPCItems.AddItem("Reader_Device.OpenCard", 0)
 45                GlobalOPCItems(1) = ConnectedGroup.OPCItems.AddItem("Reader_Device.CloseCard", 1)
 46                GlobalOPCItems(2) = ConnectedGroup.OPCItems.AddItem("Reader_Device.CardNO", 2)
 47                RefreshServerStatus() '刷新服务器状态
 48            Catch ex As Exception
 49                ConnectedOPCServer = Nothing
 50                MessageBox.Show("OPC server connect failed : " + ex.Message, "OPCSample", MessageBoxButtons.OK)
 51            End Try
 52            ResetControlStatus()
 53        End If
 54    End Sub
 55
 56    '服务器断开事件通知
 57    Private Sub OnServerShutDown()Sub OnServerShutDown(ByVal Reason As String) Handles ConnectedOPCServer.ServerShutDown
 58        btnDisconnectServer_Click(Nothing, New EventArgs())
 59    End Sub
 60
 61    Private Sub OnGroupDataChange()Sub OnGroupDataChange(ByVal TransactionID As Integer, ByVal NumItems As Integer, ByRef ClientHandles As System.Array, ByRef ItemValues As System.Array, ByRef Qualities As System.Array, ByRef TimeStamps As System.Array) Handles ConnectedGroup.DataChange
 62        For i As Integer = 1 To NumItems
 63            If Qualities(i) = OPCAutomation.OPCQuality.OPCQualityGood Then
 64                Select Case ClientHandles(i)
 65                    Case 2
 66                        txtCardNo.Text = CStr(ItemValues(i))
 67                    Case 200 '测试7张卡片
 68                        txtValueBlock0.Text = CStr(ItemValues(i))
 69                    Case 201
 70                        txtValueBlock1.Text = CStr(ItemValues(i))
 71                    Case 202
 72                        txtValueBlock2.Text = CStr(ItemValues(i))
 73                    Case 203
 74                        txtValueBlock3.Text = CStr(ItemValues(i))
 75                    Case 204
 76                        txtValueBlock4.Text = CStr(ItemValues(i))
 77                    Case 205
 78                        txtValueBlock5.Text = CStr(ItemValues(i))
 79                    Case 206
 80                        txtValueBlock6.Text = CStr(ItemValues(i))
 81                    Case 207
 82                        txtValueBlock7.Text = CStr(ItemValues(i))
 83                    Case Else
 84
 85                End Select
 86
 87            End If
 88        Next
 89    End Sub
 90
 91
 92    '断开到指定OPC服务器的连接
 93    Private Sub btnDisconnectServer_Click()Sub btnDisconnectServer_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnDisconnectServer.Click
 94        If Not (ConnectedOPCServer Is Nothing) Then
 95            Try
 96                ConnectedOPCServer.Disconnect()
 97            Catch ex As Exception
 98                MessageBox.Show("OPC server disconnect failed: " + ex.Message, "OPCSample", MessageBoxButtons.OK)
 99            Finally
100                ConnectedOPCServer = Nothing
101                ResetControlStatus()
102            End Try
103        End If
104    End Sub
105
106    '开卡，并返回卡号
107    Private Sub btnOpenCard_Click()Sub btnOpenCard_Click(ByVal sender As System.Object, ByVal e As System.EventArgs)
108        If ConnectedGroup IsNot Nothing Then
109            Try
110                '准备参数数组
111                Dim ServerHandles(1) As Integer
112                Dim ServerValues(1) As Object
113                Dim ServerErrors As System.Array
114                ServerHandles(1) = GlobalOPCItems(0).ServerHandle
115                ServerValues(1) = 1
116                '写入值，用于执行OpenCard的操作
117                ConnectedGroup.SyncWrite(1, ServerHandles, ServerValues, ServerErrors)
118                If ServerErrors(1) <> 0 Then
119                    MsgBox("OpenCardError: " & ServerErrors(1))
120                End If
121
122                ServerHandles(1) = GlobalOPCItems(2).ServerHandle
123                Dim ServerResult As System.Array
124                '读取卡号
125                ConnectedGroup.SyncRead(OPCAutomation.OPCDataSource.OPCDevice, 1, ServerHandles, ServerResult, ServerErrors)
126                If ServerErrors(1) <> 0 Then
127                    MsgBox("ReadCardNoError: " & ServerErrors(1))
128                Else
129                    txtCardNo.Text = ServerResult(1)
130                End If
131            Catch ex As Exception
132                MessageBox.Show("OPC server Open Card failed: " + ex.Message, "OPCSample", MessageBoxButtons.OK)
133            End Try
134            ResetControlStatus()
135        End If
136    End Sub
137
138    '读取卡片指定的块号的值
139    Private Sub btnReadCard_Click()Sub btnReadCard_Click(ByVal sender As System.Object, ByVal e As System.EventArgs)
140        If Not (ConnectedGroup Is Nothing) Then
141            Try
142                '获取块号
143                Dim BlockNo As Short = CByte(ReadBlockNo.Text)
144                '如果要获取数据的块所对应的项还没有创建，就创建它
145                If GlobalOPCBlockItems(BlockNo) Is Nothing Then
146                    GlobalOPCBlockItems(BlockNo) = ConnectedGroup.OPCItems.AddItem("Reader_Device.Block" & CStr(BlockNo), 200 + BlockNo)
147                End If
148                '准备参数数组
149                Dim ServerResults As System.Array
150                Dim ServerErrors As System.Array
151                Dim ServerHandles(1) As Integer
152                ServerHandles(1) = GlobalOPCBlockItems(BlockNo).ServerHandle
153                '读取值
154                ConnectedGroup.SyncRead(OPCAutomation.OPCDataSource.OPCDevice, 1, ServerHandles, ServerResults, ServerErrors)
155                If ServerErrors(1) <> 0 Then
156                    MsgBox("Read Card Failed:" & ServerErrors(1))
157                Else
158                    txtReadBlockNo.Text = ServerResults(1)
159                End If
160            Catch ex As Exception
161                MessageBox.Show("OPC server Read Card failed: " + ex.Message, "OPCSample", MessageBoxButtons.OK)
162            End Try
163        End If
164    End Sub
165
166    '写卡片指定块的值
167    Private Sub btnWriteCard_Click()Sub btnWriteCard_Click(ByVal sender As System.Object, ByVal e As System.EventArgs)
168        If Not (ConnectedGroup Is Nothing) Then
169            Try
170                '获取块号
171                Dim BlockNo As Short = CByte(WriteBlockNo.Text)
172                '如果要写入数据的块所对应的项还没有创建，就创建它
173                If GlobalOPCBlockItems(BlockNo) Is Nothing Then
174                    GlobalOPCBlockItems(BlockNo) = ConnectedGroup.OPCItems.AddItem("Reader_Device.Block" & CStr(BlockNo), 200 + BlockNo)
175                End If
176                '准备参数数组
177                Dim ServerValues(1) As Object
178                Dim ServerErrors As Array
179                Dim ServerHandles(1) As Integer
180                ServerHandles(1) = GlobalOPCBlockItems(BlockNo).ServerHandle
181                ServerValues(1) = txtWriteBlockNo.Text
182                '写入值
183                ConnectedGroup.SyncWrite(1, ServerHandles, ServerValues, ServerErrors)
184                If ServerErrors(1) <> 0 Then
185                    MsgBox("Write Card Failed:" & ServerErrors(1))
186                Else
187                    MsgBox("Write Card Succeed")
188                End If
189            Catch ex As Exception
190                MessageBox.Show("OPC server Write Card failed: " + ex.Message, "OPCSample", MessageBoxButtons.OK)
191            End Try
192        End If
193    End Sub
194
195    '重设控件状态
196    Private Sub ResetControlStatus()Sub ResetControlStatus()
197        If ConnectedOPCServer Is Nothing Then
198            btnConnectServer.Enabled = True
199            btnDisconnectServer.Enabled = False
200            btnReadCard.Enabled = False
201            btnWriteCard.Enabled = False
202            btnOpenCard.Enabled = False
203            btnCloseCard.Enabled = False
204            ReadBlockNo.Value = 0
205            WriteBlockNo.Value = 0
206            txtReadBlockNo.Text = ""
207            txtWriteBlockNo.Text = "00000000000000000000000000000000"
208            txtCardNo.Text = ""
209
210            txtSrvStartTime.Text = ""
211            txtSrvCurrTime.Text = ""
212            txtSrvGroupCount.Text = ""
213            txtSrvGroupDeadBand.Text = ""
214            txtSrvGroupDefActive.Text = ""
215            txtSrvGroupLocalID.Text = ""
216            txtSrvGroupTimeBias.Text = ""
217            txtSrvRequestRate.Text = ""
218        Else
219            btnConnectServer.Enabled = False
220            btnDisconnectServer.Enabled = True
221            If txtCardNo.Text = "" Then
222                btnReadCard.Enabled = False
223                btnWriteCard.Enabled = False
224                btnOpenCard.Enabled = True
225                btnCloseCard.Enabled = False
226            Else
227                btnReadCard.Enabled = True
228                btnWriteCard.Enabled = True
229                btnOpenCard.Enabled = True
230                btnCloseCard.Enabled = True
231            End If
232        End If
233    End Sub
234
235    '刷新服务器状态属性信息
236    Private Sub RefreshServerStatus()Sub RefreshServerStatus()
237        If ConnectedOPCServer IsNot Nothing Then
238            txtSrvStartTime.Text = ConnectedOPCServer.StartTime.ToString()
239            txtSrvCurrTime.Text = ConnectedOPCServer.CurrentTime.ToString()
240            With ConnectedOPCServer.OPCGroups
241                txtSrvGroupCount.Text = CStr(.Count)
242                txtSrvGroupDeadBand.Text = CStr(.DefaultGroupDeadband)
243                If .DefaultGroupIsActive Then
244                    txtSrvGroupDefActive.Text = "True"
245                Else
246                    txtSrvGroupDefActive.Text = "False"
247                End If
248                txtSrvGroupLocalID.Text = CStr(.DefaultGroupLocaleID)
249                txtSrvGroupTimeBias.Text = CStr(.DefaultGroupTimeBias)
250                txtSrvRequestRate.Text = CStr(.DefaultGroupUpdateRate)
251            End With
252        End If
253    End Sub
254
255    '关闭卡片
256    Private Sub btnCloseCard_Click()Sub btnCloseCard_Click(ByVal sender As System.Object, ByVal e As System.EventArgs)
257        If ConnectedGroup IsNot Nothing Then
258            Try
259                Dim ServerHandles(1) As Integer
260                Dim ServerValues(1) As Object
261                Dim ServerErrors As System.Array
262                ServerHandles(1) = GlobalOPCItems(1).ServerHandle
263                ServerValues(1) = 1
264                ConnectedGroup.SyncWrite(1, ServerHandles, ServerValues, ServerErrors)
265                If ServerErrors(1) <> 0 Then
266                    MsgBox("Close Card Error: " & ServerErrors(1))
267                End If
268            Catch ex As Exception
269                MessageBox.Show("OPC server Close Card failed: " + ex.Message, "OPCSample", MessageBoxButtons.OK)
270            End Try
271        End If
272    End Sub
273End Class
274

转载于:https://www.cnblogs.com/Phoenix-Rock/archive/2006/10/27/OPC.html