opcserverclass.cls

VB开发OPC Client的教程和源码

    
ShowOPCLastUpdateTimeError:
    Call DisplayOPC_COM_ErrorValue("LastUpdate", Err.Number)
    GetLastUpdateTime = False
    
SkipOPCLastUpdateTimeError:
End Function


' Get the major version number of the connected server
'
Function GetMajorVersion(ByRef MajorVersion As Integer)
    'Set error handling for OPC Function
    On Error GoTo ShowOPCMajorVersionError
    
    ' Attempt to get the server MajorVersion.
    MajorVersion = OPCServerObj.MajorVersion
    GetMajorVersion = True
    GoTo SkipOPCMajorVersionError
    
ShowOPCMajorVersionError:
    Call DisplayOPC_COM_ErrorValue("MajorVersion", Err.Number)
    GetMajorVersion = False
    
SkipOPCMajorVersionError:
End Function


' Get the minor version number of the connected server
'
Function GetMinorVersion(ByRef MinorVersion As Integer)
    'Set error handling for OPC Function
    On Error GoTo ShowOPCMinorVersionError
    
    ' Attempt to get the server MinorVersion.
    MinorVersion = OPCServerObj.MinorVersion
    GetMinorVersion = True
    GoTo SkipOPCMinorVersionError
    
ShowOPCMinorVersionError:
    Call DisplayOPC_COM_ErrorValue("MinorVersion", Err.Number)
    GetMinorVersion = False
    
SkipOPCMinorVersionError:
End Function


' Get the build number of the connected server
'
Function GetBuildNumber(ByRef BuildNumber As Integer)
    'Set error handling for OPC Function
    On Error GoTo ShowOPCBuildNumberError
    
    ' Attempt to get the server BuildNumber.
    BuildNumber = OPCServerObj.BuildNumber
    GetBuildNumber = True
    GoTo SkipOPCBuildNumberError
    
ShowOPCBuildNumberError:
    Call DisplayOPC_COM_ErrorValue("BuildNumber", Err.Number)
    GetBuildNumber = False
    
SkipOPCBuildNumberError:
End Function


' Get the Vendor Info of the connected server
' The vendor info will return a string describing the
' name of the vendor of the OPC server.  In some cases this string
' will return the name of the OPC Server toolkit vendor if
' the connected OPC server uses a toolkit.
'
Function GetVendorInfo(ByRef VendorInfo As String)
    'Set error handling for OPC Function
    On Error GoTo ShowOPCVendorInfoError
        
    ' Attempt to get the server VendorInfo.
    VendorInfo = OPCServerObj.VendorInfo
    GetVendorInfo = True
    GoTo SkipOPCVendorInfoError
    
ShowOPCVendorInfoError:
    Call DisplayOPC_COM_ErrorValue("VendorInfo", Err.Number)
    GetVendorInfo = False
    
SkipOPCVendorInfoError:
End Function


' Get the Server State property of the connected server
' The value retured will be one of the following
' OPC_STATUS_RUNNING      - 1 - Server is running normally
' OPC_STATUS_FAILED       - 2 - Vendor specific fatal error has occured
' OPC_STATUS_NOCONFIG     - 3 - Server Running but no Configuration Data available
' OPC_STATUS_SUSPENDED    - 4 - Server is suspended and not receiving data
' OPC_STATUS_TEST         - 5 - Server in test mode
' OPC_STATUS_DISCONNECTED - 6 - Server has disconnected
'
Function GetServerState(ByRef ServerState As Long)
    'Set error handling for OPC Function
    On Error GoTo ShowOPCServerStateError
    
    ' Attempt to get the server ServerState.
    ServerState = OPCServerObj.ServerState
    GetServerState = True
    GoTo SkipOPCServerStateError
    
ShowOPCServerStateError:
    Call DisplayOPC_COM_ErrorValue("ServerState", Err.Number)
    GetServerState = False
    
SkipOPCServerStateError:
End Function

' This function returns an OPC browse object from the server object
' held in this instance of the OPCServerClass.  This function may return
' a true condition indicating that the function succeeded, however the
' the OPCBrowserObject may still be set to Nothing if the connected
' server does not support browsing.  With that in mind check the
' returned object for "Nothing" before use.

Function GetServerBrowseObject(ByRef OPCBrowserObject As OPCBrowserClass)
    'Set error handling for OPC Function
    On Error GoTo ShowOPCBrowserError
    
    Dim OPCBrowserObj As OPCBrowser
        
    ' Attempt to get the server browse object
    Set OPCBrowserObj = OPCServerObj.CreateBrowser
    If Not OPCBrowserObj Is Nothing Then
        Set OPCBrowserObject = New OPCBrowserClass
        OPCBrowserObject.SetBrowserObject OPCBrowserObj
    Else
        Set OPCBrowserObject = Nothing
    End If
    GetServerBrowseObject = True
    GoTo SkipOPCBrowserError
    
ShowOPCBrowserError:
    Call DisplayOPC_COM_ErrorValue("Browser Object", Err.Number)
    GetServerBrowseObject = False
    
SkipOPCBrowserError:
End Function

' The next section of this module covers the management of OPC groups
' within the OPCServerClass object. When adding an OPC group the initial
' state of the groups atrributes must be set.  A group has the following
' attributes, GroupName, Update Rate, DeadBand, and ActiveState.  The
' actual ServerGroups.Add function only allows you to specify the group
' name when adding a new group.  To set the attributes listed above you
' can use the Set Default functions that follow to establish the initial
' conditions for a new group.



' The SetDefaultGroupIsActive allows you to set the default active
' condition on the ServerGroups object determining the active
' state of a newly added group.  Once a group is added you can change
' these attributes by using the functions found in the OPCGroupClass
' object. The active state of a group allows you to literally turn the
' data in this group on or off.  For the OPC server this means that
' your application either needs the data in the group(On/Active) or
' it doesn't(Off/Inactive).  Using the active state of the group
' your VB application can tailor how much data the OPC server is trying
' read from your devices.  By turing a group off that you don't
' currently need you can reduce the amount of data the OPC server is
' reading from a device.  This of course has the benefit of increasing
' the performance of the OPC server for the data items that you do still
' need to acquire.  I recommend using the active state of the group or
' of the item(shown later), instead of continuously adding and removing
' items from a group as a means of controlling what data the OPC server
' is gathering from the devices.
'
Function SetDefaultGroupIsActive(ByVal State As Boolean)
    'Set error handling for OPC Function
    On Error GoTo ShowOPCDefaultGroupIsActiveError
    
    ServerGroups.DefaultGroupIsActive = State
    SetDefaultGroupIsActive = True
    GoTo SkipOPCDefaultGroupIsActiveError
    
ShowOPCDefaultGroupIsActiveError:
    Call DisplayOPC_COM_ErrorValue("DefaultGroupIsActive", Err.Number)
    SetDefaultGroupIsActive = False
    
SkipOPCDefaultGroupIsActiveError:
End Function


' The SetDefaultGroupUpdateRate allows you to set the default UpdateRate
' condition on the ServerGroups object determining the Update Rate
' of a newly added group.  Once a group is added you can change
' these attributes by using the functions found in the OPCGroupClass
' object. The update rate is entered in milliseconds.  The range is
' 0 to 2147483647 milliseconds which is about 596 hours. Entering
' value of 0 tells the OPC server you want it to acquire data in this
' group as fast as possible.  The update rate on a group is very
' powerful tool for optimizing your application's communications.
' If you set every group you add to a server to an update interval of
' 0 the server will attempt to gather all of your data as quickly as
' possible.  If all of your data requires the best possible update
' speed then this is probably OK.  But what if some of your data doesn't
' really change but once every 10 minutes or so.  To read this as fast
' as possible would waste a considerable amount of the communications
' bandwidth of your OPC server.  Since the OPC server allows you to add
' multiple groups to the server you can separate your data into separate
' groups, with each group having its own update rate.  In this way fast
' data can be gathered quickly and slow data can be gathered slowly.
'
Function SetDefaultGroupUpdateRate(ByVal Rate As Long)
    'Set error handling for OPC Function
    On Error GoTo ShowOPCDefaultUpdateRateError
    
    ServerGroups.DefaultGroupUpdateRate = Rate
    SetDefaultGroupUpdateRate = True
    GoTo SkipOPCDefaultUpdateRateError
    
ShowOPCDefaultUpdateRateError:
    Call DisplayOPC_COM_ErrorValue("SetDefaultGroupUpdateRate", Err.Number)
    SetDefaultGroupUpdateRate = False
    
SkipOPCDefaultUpdateRateError:
End Function


' The SetDefaultGroupDeadBand allows you to set the default Deadband
' condition on the ServerGroups object determining the DeadBand
' of a newly added group.  Once a group is added you can change
' these attributes by using the functions found in the OPCGroupClass
' object.  Deadband is an interesting feature of the an OPC server.
' Deadband allows you to limit the amount of data changes the OPC
' will return for items in this group.  It does this by establishing the
' ratio of change that must occur in a given item before the OPC server
' will pass the changed value back to the connected OPC client.
' The Deadband ranges from 0 to 100 percent. The actual percentage of
' effect that the deadband has upon changing data depends of the
' data tpye of the OPC item.  If the data type of the OPC item is a BYTE
' which has a range of 0 to 255 a deadband value of 1 percent would
' require that the value contained in this BYTE item must change by
' atleast 2.5 before the OPC server will inform the OPC client of the
' change.  Unlike the the Active state and Update Rate of a group the
' Deadband feature will not optimize the communications bandwidth of the
' OPC server.  Deadband is more likely to be used to prevent an
' application like a data logger from logging every little change in
' value due to a noisy enviroment as an example.
'
Function SetDefaultGroupDeadBand(ByVal DeadBand As Single)
    'Set error handling for OPC Function
    On Error GoTo ShowOPCDefaultGroupDeadBandError
    
    ServerGroups.DefaultGroupDeadband = DeadBand
    SetDefaultGroupDeadBand = True
    GoTo SkipOPCDefaultGroupDeadBandError
    
ShowOPCDefaultGroupDeadBandError:
    Call DisplayOPC_COM_ErrorValue("SetDefaultGroupDeadBand", Err.Number)
    SetDefaultGroupDeadBand = False
    
SkipOPCDefaultGroupDeadBandError:
End Function


' The name say it all, gets the default active state from the
' ServerGroups collection object.
'
Function GetDefaultGroupIsActive(ByRef State As Boolean)
    'Set error handling for OPC Function
    On Error GoTo ShowOPCGetDefaultGroupIsActiveError
    
    State = ServerGroups.DefaultGroupIsActive
    GetDefaultGroupIsActive = True
    GoTo SkipOPCGetDefaultGroupIsActiveError
    
ShowOPCGetDefaultGroupIsActiveError:
    Call DisplayOPC_COM_ErrorValue("GetDefaultGroupIsActive", Err.Number)
    GetDefaultGroupIsActive = False
    
SkipOPCGetDefaultGroupIsActiveError:
End Function


' The name say it all, gets the default UpdateRate from the
' ServerGroups collection object.
'
Function GetDefaultGroupUpdateRate(ByRef Rate As Long)
    'Set error handling for OPC Function
    On Error GoTo ShowOPCGetDefaultUpdateRateError