RS232.dll + Game maker = automaçao comercial

tenho um dll que diz comunicar com a serial com3 USB , preciso de algum metodo que o game maker comunique com as portas com3 USB para enviar bits , exemplo enviar letra "q"

o DLL RS232.dll tem uma funçao de :



com=2//this is the com port that the arduino is connected to.
mplay_init_serial(com,9600,0,2,0);//open the serial port in order to allow access for the RS232 Dll
mplay_session_create(1,1,1)//and create a session to allow access
mplay_session_end()//close the session
mplay_end()//end mplay because only 1 function can connect to the port at one time.
RS232_Startup();//Not needed if you are using the extension.
RS232_CreatePort("COM"+string(com),1) //create the port
RS232_SetPortProperties(9600,1,2,0,1);
mode=0 //inititiate the mode variable
// for this example 0=off, 1=constant on, 2=blink
RS232_WriteByte(mode,1) //wryte the byte telling the light to turn off
can=true //toggle check variable
read=0; //initialize reading variables to read from the arduino
read1=0;




mode=get_integer("letra?",0);
RS232_WriteByte(mode,1)


porem nao ativa a porta do arduino que eu configurei para receber a letra "a" de exemplo , deve ser alguma configuraçao de velocidade ou parametros de config no codigo acima, se alguem tiver alguma dll diferente que possa se comunicar com o COM3 , que possa WriteByte na porta me ajuda por favor, preciso terminar meu projeto...

corrigindo
com=3//this is the com port that the arduino is connected to.
mplay_init_serial(com,9600,0,2,0);//open the serial port in order to allow access for the RS232 Dll
mplay_session_create(1,1,1)//and create a session to allow access
mplay_session_end()//close the session
mplay_end()//end mplay because only 1 function can connect to the port at one time.
RS232_Startup();//Not needed if you are using the extension.
RS232_CreatePort("COM"+string(com),1) //create the port
RS232_SetPortProperties(9600,1,2,0,1);
mode=0 //inititiate the mode variable
// for this example 0=off, 1=constant on, 2=blink
RS232_WriteByte(mode,1) //wryte the byte telling the light to turn off
can=true //toggle check variable
read=0; //initialize reading variables to read from the arduino
read1=0;




mode=get_integer("letra?",0);
RS232_WriteByte(mode,1)