OPC 客户端代码，VB的

1. EXAMPLE
   
2. The brief coding example below connects to the Ovation OPC Server, adds a group, adds
   
3. items, reads values and writes values.
   
4. 1. Start up the Visual Basic Program or the Visual Basic for Applications environment for
   
5. an Microsoft Office Product. Add the OPC Automation Library 2.0 (opcdaauto.dll) to the
   
6. list of references using the Tools\References menu item.
   
7. 2. Copy the example subroutine below into a module. Execute the code from the
   
8. debugger.
   
9. Option Explicit
   
10. ' This is an example of the use of Ovation OPC
    
11. ' This simple example will have to be modified to be
    
12. ' used by an Ovation system. The correct machine name
    
13. ' and correct point names must be inserted in the appropriate
    
14. ' variables
    
15. Sub OPCExample()
    
16. Dim myOPCServer As OPCServer
    
17. Dim myOPCBrowser As OPCBrowser
    
18. Dim myOPCGroup As OPCGroup
    
19. Dim myOPCItem(3) As OPCItem
    
20. Dim OPCItemTemp As OPCItem
    
21. Dim myServerName As String
    
22. Dim myNodeName As String
    
23. Dim myGroupName As String
    
24. Dim myItemName(3) As String
    
25. Dim i As Integer
    
26. Dim lCount As Long
    
27. Dim lClientHandle As Long
    
28. Dim myClientHandles(3) As Long
    
29. Dim myServerHandles() As Long
    
30. Dim myErrors() As Long
    
31. Dim lReturn As Long
    
32. Dim myValue As Variant
    
33. Dim myQuality As Variant
    
34. Dim myTimeStamp As Variant
    
35. B.2 Automation Interface
    
36. B-2 U3-1036 (Rev 1)
    
37. Emerson Process Management Proprietary Class 2C
    
38. '
    
39. ' Modify these as needed for a specific
    
40. ' OPC Server/group/item
    
41. '
    
42. myServerName = "Ovation.OPC.4"
    
43. myNodeName = "Drop200"
    
44. myGroupName = "Group"
    
45. '
    
46. ' This name must definitely be modified
    
47. ' to match a legal name on the OvationHighway
    
48. ' The syntax for a fully qualified Ovation Item is:
    
49. ' Point.Unit@Network.Field
    
50. '
    
51. ' ex. la006-122.Unit1@w3.HL
    
52. '
    
53. ' Create a new server
    
54. Set myOPCServer = New OPCServer
    
55. ' Connect to the Ovation OPC Server
    
56. On Error GoTo NoConnect
    
57. Call myOPCServer.Connect(myServerName, myNodeName)
    
58. Set myOPCBrowser = myOPCServer.CreateBrowser
    
59. ' Add a group
    
60. On Error GoTo NoGroup
    
61. Set myOPCGroup = myOPCServer.OPCGroups.Add(myGroupName)
    
62. '
    
63. ' modify some group values
    
64. '
    
65. myOPCGroup.UpdateRate = 500
    
66. myGroupName = "Group2"
    
67. myOPCGroup.Name = myGroupName
    
68. '
    
69. ' add 3 OPC Items
    
70. '
    
71. On Error GoTo NoAddItem
    
72. ' initialize data
    
73. myItemName(1) = "la006-122"
    
74. myItemName(2) = "da006-122"
    
75. myItemName(3) = "ld006-122"
    
76. myClientHandles(1) = 2500
    
77. myClientHandles(2) = 2501
    
78. myClientHandles(3) = 2502
    
79. Call myOPCGroup.OPCItems.AddItems(3, _
    
80. myItemName, _
    
81. myClientHandles, _
    
82. myServerHandles, _
    
83. myErrors)
    
84. ' read the data
    
85. For Each OPCItemTemp In myOPCGroup.OPCItems
    
86. Call OPCItemTemp.Read(0, myValue, myQuality, myTimeStamp)
    
87. Debug.Print OPCItemTemp.ItemID & " " & myValue & " quality " &
    
88. myQuality & " time " & myTimeStamp
    
89. Next OPCItemTemp
    
90. ' write the data
    
91. On Error GoTo NoWrite
    
92. B.2 Automation Interface
    
93. U3-1036 (Rev 1) B-3
    
94. Emerson Process Management Proprietary Class 2C
    
95. Set OPCItemTemp = myOPCGroup.OPCItems.GetOPCItem(myServerHandles(1))
    
96. OPCItemTemp.Write (OPCItemTemp.Value + 1#)
    
97. Set OPCItemTemp = myOPCGroup.OPCItems.GetOPCItem(myServerHandles(2))
    
98. OPCItemTemp.Write (OPCItemTemp.Value + 1#)
    
99. Set OPCItemTemp = myOPCGroup.OPCItems.GetOPCItem(myServerHandles(3))
    
100. OPCItemTemp.Write (Not OPCItemTemp.Value)
     
101. For Each OPCItemTemp In myOPCGroup.OPCItems
     
102. OPCItemTemp.Write (OPCItemTemp.Value + 1)
     
103. Call OPCItemTemp.Read(0, myValue, myQuality, myTimeStamp)
     
104. Debug.Print OPCItemTemp.ItemID & " " & myValue & " quality " &
     
105. myQuality & " time " & myTimeStamp
     
106. Next OPCItemTemp
     
107. '
     
108. ' Leave with the quiet confidence of a job well done
     
109. '
     
110. On Error GoTo RemoveItemsFault
     
111. lCount = myOPCGroup.OPCItems.Count
     
112. Call myOPCGroup.OPCItems.Remove(lCount, myServerHandles, myErrors)
     
113. myOPCServer.OPCGroups.Remove (myGroupName)
     
114. myOPCServer.Disconnect
     
115. Exit Sub
     
116. NoWrite:
     
117. Debug.Print "Write Item " & " returns error; " & Err.Number & "; ("
     
118. & Err.Description & "); """
     
119. Resume Next
     
120. NoAddItem:
     
121. Debug.Print "Add Item " & myOPCItem(i).ItemID & " returns error " &
     
122. Err.Number & " (" & Err.Description & ")"
     
123. Resume Next
     
124. RemoveItemsFault:
     
125. Debug.Print "Remove Items returns error " & Err.Number & " (" &
     
126. Err.Description & ")"
     
127. myOPCServer.OPCGroups.Remove (myGroupName)
     
128. myOPCServer.Disconnect
     
129. Exit Sub
     
130. NoGroup:
     
131. MsgBox "Can't add group " & myGroupName
     
132. myOPCServer.Disconnect
     
133. Exit Sub
     
134. NoConnect:
     
135. ' fail to connect
     
136. MsgBox "Connect to " & myNodeName & " Server " & myServerName
     
137. Exit Sub
     
138. End Sub

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