subroutine TopDrive_MainSolver
    
    !use CDataDisplayConsoleVariables
    !use CDrillingConsoleVariables
    ! use CSimulationVariables
    use TopDrive_VARIABLES
    use CDrillWatchVariables
    use CWarningsVariables
    use CSounds
    use CTopDrivePanelVariables
    
    IMPLICIT NONE
    
    !if ( (TopDriveTdsPowerState==-1) .and. (RpmKnob==0.) ) then  !FWD
    if ( TopDrivePanel%TopDriveTdsPowerState==-1 ) then  !.and. (IsStopped == .false.)
        TDS%SoundBlower = .true.
        !Call SetSoundBlowerRT(TDS%SoundBlower)
        TopDrivePanel%TopDriveTdsPowerLed = 1 
        !IF ( RTTransmissionLever /=0 .and. RotaryGearsAbuse==0 ) THEN  !be in clutch mode  ????
        TDS%N_new = (TopDrivePanel%RpmKnob/250.d0)*965.d0          ! 0<RpmKnob<250  , 0<TDS%N_ref(truction motor)<965
        
        !===> Top Drive Malfunction ----> Drive Motor Failure
        call TopDrive_Malfunction_MotorFailure
        
        if (((TDS%N_new-TDS%N_old)/TDS%time_step)>193.) then
            TDS%N_ref = (193.*TDS%time_step)+TDS%N_old
        else if (((TDS%N_old-TDS%N_new)/TDS%time_step)>193.) then
            TDS%N_ref = (-193.*TDS%time_step)+TDS%N_old
        else
            TDS%N_ref = TDS%N_new
        end if
        CALL TopDrive_INPUTS
        CALL TopDrive_Solver
        TDS%N_old = TDS%N_ref
    !else if ( (TopDriveTdsPowerState==1) .and. (RpmKnob==0.) ) then   !REV
    else if ( (TopDrivePanel%TopDriveTdsPowerState==1)   ) then   !REV .and. (IsStopped == .false.)
        TDS%SoundBlower = .true.
        !Call SetSoundBlowerRT(TDS%SoundBlower)
        TopDrivePanel%TopDriveTdsPowerLed = 1
        TDS%N_new = (TopDrivePanel%RpmKnob/250.d0)*965.d0
        
        !===> Top Drive Malfunction ----> Drive Motor Failure
        call TopDrive_Malfunction_MotorFailure
        
        if (((TDS%N_new-TDS%N_old)/TDS%time_step)>193.) then
            TDS%N_ref = (193.*TDS%time_step)+TDS%N_old
        else if (((TDS%N_old-TDS%N_new)/TDS%time_step)>193.) then
            TDS%N_ref = (-193.*TDS%time_step)+TDS%N_old
        else
            TDS%N_ref = TDS%N_new
        end if
        CALL TopDrive_INPUTS
        CALL TopDrive_Solver
        TDS%N_old = TDS%N_ref                
    else
        if( (TopDrivePanel%TopDriveTdsPowerState /= 0)   ) then !.and. (IsStopped == .false.)
            TDS%SoundBlower = .true.
            !Call SetSoundBlowerRT(TDS%SoundBlower)
            TopDrivePanel%TopDriveTdsPowerLed = 1
        else
            TDS%SoundBlower = .false.
            !Call SetSoundBlowerRT(TDS%SoundBlower)
            TopDrivePanel%TopDriveTdsPowerLed = 0
        end if
        Call TopDrive_OffMode
    end if
end subroutine TopDrive_MainSolver