protected unsafe void EnableActionStateVariablePeriod()
        {
            iCallbackStateVariablePeriod = new CallbackStateVariablePeriod(DoStateVariablePeriod);
            IntPtr ptr = GCHandle.ToIntPtr(iGch);

            DvServiceLinnCoUkDiagnostics1EnableActionStateVariablePeriod(iHandle, iCallbackStateVariablePeriod, ptr);
        }
 static extern void DvServiceLinnCoUkDiagnostics1EnableActionStateVariablePeriod(uint aHandle, CallbackStateVariablePeriod aCallback, IntPtr aPtr);