OPC DA Auto 2.02 Specification

Purpose......Page 10
Audience......Page 11
Functional Requirements......Page 12
OPC Data Access Automation Object Model......Page 13
Collections......Page 14
Type Library......Page 15
About the OPC Data Access Automation Wrapper DLL......Page 16
Dim AnOPCServerTime As DateAnOPCServerTime = AnOPCServer.StartTime......Page 17
Dim AnOPCServerMinorVersion As StringAnOPCServerMinorVersion = Str(AnOPCServer.MinorVersion)......Page 18
The server has been temporarily suspended via some vendor specific method and is not getting or sending data. Note that Quality will be returned as OPC_QUALITY_OUT_OF_SERVICE.......Page 19
Dim Bandwidth As LongBandwidth = AnOPCServer.Bandwidth......Page 20
ServerNode As String......Page 21
AllOPCServers = AnOPCServer.GetOPCServers......Page 22
AnOPCServer.Connect (ARealOPCServer, ARealOPCNodeName)......Page 23
‘ for this sample, assume while adding some items......Page 24
DWORD ids for the returned properties. These IDs can be passed to GetItemProperties or LookupItemIDs......Page 25
DWORD ids for the requested properties. These IDs were returned by QueryAvailableProperties or obtained from the fixed list described earlier.......Page 26
DWORD ids for the requested properties. These IDs were returned by QueryAvailableProperties......Page 27
Dim WithEvents AnOPCServer As OPCServer......Page 28
End Sub......Page 29
Filter......Page 30
VB Syntax Example (getting the property):Dim TheFilter As String......Page 31
AnOPCServerBrowser.AccessRights =  OPCWritable......Page 32
’ 1st method for getting all namesFor I = 1 To......Page 33
the collection is filled with all leafs at the current browse position......Page 34
Dim branches(3) As String......Page 35
Description......Page 36
AnOPCServerBrowser.MoveDown “Mixing”Set AnAcces......Page 37
DefaultGroupUpdateRate......Page 38
VB Syntax Example (getting the property):Dim DefaultGroupUpdateRate As Long......Page 39
OPCGroups Methods......Page 40
Name of the group. The name must be unique among the other groups created by this client. If no name is provided, The server-generated name will also be unique relative to any existing groups.......Page 41
‘   some more code here......Page 42
The ServerHandle returned by ConnectPublicGroup, or the name of a Public OPCGroup.......Page 43
NOTE – it is recommended that the event OnDataCha......Page 44
End Sub......Page 45
Name......Page 46
Name of the group. The name must be a unique group name, with respect to the naming of other groups created by this client.......Page 47
VB Syntax Example (setting the property):Dim CurrentValue As BooleanSet MyGroups = AnOPCServer.OPCGroups......Page 48
‘   some more code here......Page 49
‘   some more code here......Page 50
OneGroup.DeadBand = 5......Page 51
SyncRead(Source As Integer, NumItems As Long, ServerHandles() As Long, ByRef Values() As Variant,  ByRef Errors() As Long, Optional ByRef Qualities As Variant, Optional ByRef TimeStamps As Variant)......Page 52
SyncWrite......Page 53
Dim ServerHandles() As Long......Page 54
A Server generated transaction ID. This is provid......Page 55
Description......Page 56
End Sub......Page 57
End Sub......Page 58
The client specified transaction ID.  A non-0 value for this indicates that this call has been generated as a result of an AsyncRefresh.  A value of 0 indicates that this call has been generated as a result of normal subscription processing.......Page 59
Array of Long’s indicating the success of the ind......Page 60
The client specified transaction ID. This is incl......Page 61
End Sub......Page 62
DefaultAccessPath......Page 63
VB Syntax Example (setting the property):AnOPCItemCollection.DefaultAccessPath = SomeValue......Page 64
NOTE: do not confuse the automation 'Item' property with the OPCItem object. The automation 'Item' is a special reserved property used in a generic way by automation collections to refer to the items they contain. The OPCItem is an OPC Automation specifi......Page 65
AnOPCItemCollection.AddItem AnOPCItemID AnClientHandle......Page 66
AnOPCItemCollection.AddItems AddItemCount, AnOPCItemIDs, ClientHandles,  AnOPCItemServerHandles, AnOPCItemServerErrors, AnOPCRequestedDataTypes, AnOPCAccessPathss......Page 67
Appendix A - OPC Automation Error HandlingAppendix D- Notes On Automation Data Types......Page 68
‘ add code to process any errors that are returne......Page 69
Array of Long’s indicating the success of the ind......Page 70
AnOPCItemCollection.SetDataTypes ItemCount, AnOPCItemServerHandles, RequestedDataTypes, AnOPCItemServerErrors......Page 71
VB Syntax Example (setting the property):AnOPCItem.ClientHandle = SomeValue......Page 72
VB Syntax Example (getting the property):Dim CurrentValue As LongDim SomeValue As LongCurrentValue = AnOPCItem.AccessRights......Page 73
Dim AnOPCItem as OPCItemSet OPCItem = GetOPCItem(SomeItemServerHandle)VB Syntax Example (getting the property):Dim CurrentValue As IntegerDim SomeValue As IntegerCurrentValue = AnOPCItem.RequestedDataTypeVB Syntax Example (setting the property......Page 74
Appendix A - OPC Automation Error Handling......Page 75
Read makes a blocking call to read this item from......Page 76
Dim Value As Variant......Page 77
End Sub......Page 78
OPCErrors......Page 79
Appendix A - OPC Automation Error Handling......Page 81
Appendix B – Sample String Filter Syntax Function......Page 83
Appendix C - Data Access Automation IDL Specification......Page 85
Appendix D- Notes On Automation Data Types......Page 100