void checkServo( void )
{
	const int 			MAX_PULSE	= 1900 ;
	const int 			MIN_PULSE	= 1000 ;
	const int 			BASE_PULSE	= 50 ;
	const int 			NB_STEPS 	= 500 ;
	const unsigned char SERVO[] 	= "0" ;

	unsigned char 		trama[100] ;
	int 				deltaPulse ;
	unsigned char 		mvtStatus ;
	unsigned char 		*ind ;
	int 				pulse ;
	int 				refPulse ;
	int 				digitPulse ;
	static bool			notInit = false ;

	refPulse = ( MIN_PULSE + MAX_PULSE ) / 2;
	deltaPulse = BASE_PULSE ;
	for ( int ic=0 ; ic<NB_STEPS; ic++ )
	{
		if ( refPulse <= MIN_PULSE )
			deltaPulse = BASE_PULSE ;
		else if ( refPulse >= MAX_PULSE )
			deltaPulse = -BASE_PULSE ;
		refPulse = refPulse + deltaPulse ;

		//codify reference
		ind = trama ;
		*ind = '#' ;
		ind++ ;
		*ind = SERVO[0] ;
		ind++ ;
		if ( SERVO[1] != '\0' )
		{
			*ind = SERVO[1] ;
			ind++ ;
		}
		*ind = ' ' ;
		ind++ ;

		//codify pulse
		*ind = 'P' ;
		ind++ ;
		pulse = refPulse ;
		digitPulse = pulse / 1000 ;
		if ( digitPulse > 0 )
		{
			*ind = '0' + (char)digitPulse ;
			ind++ ;
		}
		pulse = pulse - (digitPulse*1000) ;
		digitPulse = pulse / 100 ;
		*ind = '0' + (char)digitPulse ;
		*ind++ ;
		pulse = pulse - (digitPulse*100) ;
		digitPulse = pulse / 10 ;
		*ind = '0' + (char)digitPulse ;
		*ind++ ;
		pulse = pulse - (digitPulse*10) ;
		digitPulse = pulse ;
		*ind = '0' + (char)digitPulse ;
		ind++ ;
		*ind = ' ' ;
		ind++ ;

		//codify speed
		if ( notInit )
		{
			*ind = 'S' ;
			ind++ ;
			*ind = '5' ;
			ind++ ;
			*ind = '0' ;
			ind++ ;
			*ind = '0' ;
			ind++ ;
			*ind = '0' ;
			ind++ ;
		}
		else
		{
			notInit = true ;
		}

		//*ind = '\0' ; //must finish with NULL
		//cout << "\nSSC32COMMANDFRAME<" << trama << "> " << endl ;
		*ind = '\r' ;

		///BEHAVIOUR IS FINE WITH SPEED=5000 AND USLEEP=2X100000 AND WITHOUT QUERY
		usleep( 100000 ) ;
		usleep( 100000 ) ;
		rs232Port->send( trama, (ind - trama + 1) ) ;

		/**SAME CODE WITH QUERY (next cycle) : THE SERVO IS SLOWER AND STOPS FROM TIME TO TIME DURING A HALF SECOND : WHY ???
		   PROOF USED SERVOS HITECH HS-985MG AND HITECH HS-85MG
		**/
		do {
			rs232Port->send( (unsigned char *)"Q\r", 2 ) ; //mvt query
			rs232Port->receive( &mvtStatus, sizeof(mvtStatus) ) ;
			//usleep( 2000 ) ;
			//cout << '.' ;
		} while ( mvtStatus != '.' ) ; //=='+' while mvt is not ended
		/**/
	}
}