Truss CreateTruss(Autodesk.Revit.DB.Document document, 
    FamilyInstance column1, FamilyInstance column2)
{
    Truss truss = null;
    using (Transaction transaction = new Transaction(document, "Add Truss"))
    {
       if (transaction.Start() == TransactionStatus.Started)
       {
           //sketchPlane
           XYZ origin = new XYZ(0, 0, 0);
           XYZ xDirection = new XYZ(1, 0, 0);
           XYZ yDirection = new XYZ(0, 1, 0);
           Plane plane = document.Application.Create.NewPlane(xDirection, yDirection, origin);
           SketchPlane sketchPlane = SketchPlane.Create (document, plane);

           //new base Line - use line that spans two selected columns
           AnalyticalModel frame1 = column1.GetAnalyticalModel() as AnalyticalModel;
           XYZ centerPoint1 = (frame1.GetCurve() as Line).GetEndPoint(0);

           AnalyticalModel frame2 = column2.GetAnalyticalModel() as AnalyticalModel;
           XYZ centerPoint2 = (frame2.GetCurve() as Line).GetEndPoint(0);

           XYZ startPoint = new XYZ(centerPoint1.X, centerPoint1.Y, 0);
           XYZ endPoint = new XYZ(centerPoint2.X, centerPoint2.Y, 0);
           Autodesk.Revit.DB.Line baseLine = null;

           try
           {
               baseLine = Line.CreateBound(startPoint, endPoint);
           }
           catch (System.ArgumentException)
           {
               throw new Exception("Selected columns are too close to create truss.");
           }

           // use the active view for where the truss's tag will be placed; View used in
           // NewTruss should be plan or elevation view parallel to the truss's base line 
           Autodesk.Revit.DB.View view = document.ActiveView;

           // Get a truss type for the truss
           FilteredElementCollector collector = new FilteredElementCollector(document);
           collector.OfClass(typeof(FamilySymbol));
           collector.OfCategory(BuiltInCategory.OST_Truss);

           TrussType trussType = collector.FirstElement() as TrussType;

           if (null != trussType)
           {
               truss = Truss.Create(document, trussType.Id, sketchPlane.Id, baseLine);
               transaction.Commit();
           }
           else
           {
               transaction.RollBack();
               throw new Exception("No truss types found in document.");
           }
       }
    }

    return truss;
}

Private Function CreateTruss(document As Autodesk.Revit.DB.Document, column1 As FamilyInstance, column2 As FamilyInstance) As Truss
    Dim truss__1 As Truss = Nothing
    Using transaction As New Transaction(document, "Add Truss")
        If transaction.Start() = TransactionStatus.Started Then
            'sketchPlane
            Dim origin As New XYZ(0, 0, 0)
            Dim xDirection As New XYZ(1, 0, 0)
            Dim yDirection As New XYZ(0, 1, 0)
            Dim plane As Plane = document.Application.Create.NewPlane(xDirection, yDirection, origin)
            Dim sketchPlane__2 As SketchPlane = SketchPlane.Create(document, plane)

            'new base Line - use line that spans two selected columns
            Dim frame1 As AnalyticalModel = TryCast(column1.GetAnalyticalModel(), AnalyticalModel)
            Dim centerPoint1 As XYZ = TryCast(frame1.GetCurve(), Line).GetEndPoint(0)

            Dim frame2 As AnalyticalModel = TryCast(column2.GetAnalyticalModel(), AnalyticalModel)
            Dim centerPoint2 As XYZ = TryCast(frame2.GetCurve(), Line).GetEndPoint(0)

            Dim startPoint As New XYZ(centerPoint1.X, centerPoint1.Y, 0)
            Dim endPoint As New XYZ(centerPoint2.X, centerPoint2.Y, 0)
            Dim baseLine As Autodesk.Revit.DB.Line = Nothing

            Try
                baseLine = Line.CreateBound(startPoint, endPoint)
            Catch generatedExceptionName As System.ArgumentException
                Throw New Exception("Selected columns are too close to create truss.")
            End Try

            ' use the active view for where the truss's tag will be placed; View used in
            ' NewTruss should be plan or elevation view parallel to the truss's base line 
            Dim view As Autodesk.Revit.DB.View = document.ActiveView

            ' Get a truss type for the truss
            Dim collector As New FilteredElementCollector(document)
            collector.OfClass(GetType(FamilySymbol))
            collector.OfCategory(BuiltInCategory.OST_Truss)

            Dim trussType As TrussType = TryCast(collector.FirstElement(), TrussType)

            If trussType IsNot Nothing Then
                truss__1 = Truss.Create(document, trussType.Id, sketchPlane__2.Id, baseLine)
                transaction.Commit()
            Else
                transaction.RollBack()
                Throw New Exception("No truss types found in document.")
            End If
        End If
    End Using

    Return truss__1
End Function