用VB.NET编程语言对UG8.5进行的二次开发，创建一个Public Function来获取当前活动文档中所有显示的实体上所有法向为Z轴正方向的平面，并高亮显示平面上所有的圆孔边，如果没有提示没有圆边.

好的，我明白了。对于你的问题，我可以提供以下代码作为参考：

Public Function GetZAxisPlanesWithCircularEdges() As List(Of NXObject)

    Dim theSession As Session = Session.GetSession()
    Dim workPart As Part = theSession.Parts.Work
    Dim displayPart As Part = theSession.Parts.Display

    Dim zAxis As Vector3d = New Vector3d(0, 0, 1)
    Dim zAxisTolerance As Double = 0.01 ' Set your own tolerance value here

    Dim planesWithCircularEdges As List(Of NXObject) = New List(Of NXObject)

    Dim objects As NXObject() = displayPart.NXOpenTaggedObjectManager.GetTaggedObjects()
    For Each obj As NXObject In objects
        If TypeOf obj Is Face Then
            Dim face As Face = CType(obj, Face)
            Dim plane As Plane = face.GetPlane()
            Dim normal As Vector3d = plane.Normal

            If normal.IsParallelTo(zAxis, zAxisTolerance) Then
                Dim edges() As Edge = face.GetEdges()
                For Each edge As Edge In edges
                    If TypeOf edge.Geometry Is Arc Then
                        planesWithCircularEdges.Add(face)
                        For Each curve As Curve In edge.GetConnectedCurves()
                            If TypeOf curve Is Circle Then
                                Dim circle As Circle = CType(curve, Circle)
                                Dim circleEdge As Edge = circle.GetEdge()
                                circleEdge.Highlight()
                            End If
                        Next
                        Exit For
                    End If
                Next
            End If
        End If
    Next

    If planesWithCircularEdges.Count = 0 Then
        MessageBox.Show("No circular edges found on planes with Z-axis as the normal direction.")
    End If

    Return planesWithCircularEdges

End Function

这个函数会遍历当前活动文档中所有的面，并检查它们的法向是否为Z轴正方向。如果是，那么它会检查这个面上是否有圆形边。如果有，那么它会将这个面加入到一个列表中，并高亮显示所有的圆形边。

如果没有找到任何符合条件的面，它会弹出一个消息框提示没有找到圆形边。

请根据你的实际需求进行修改和调整。