Ist eine Konstante

Defined in ntddser.h. Include ntddser.h.

http://www.sysinternals.com/Utilities/Portmon.html
Hier mit kanst du mit hören was dein Comport so mach for allem was das Terminal prg so tut.

Code:
#define IOCTL_SERIAL_SET_BAUD_RATE      CTL_CODE(FILE_DEVICE_SERIAL_PORT, 1,METHOD_BUFFERED,FILE_ANY_ACCESS)
#define IOCTL_SERIAL_SET_QUEUE_SIZE     CTL_CODE(FILE_DEVICE_SERIAL_PORT, 2,METHOD_BUFFERED,FILE_ANY_ACCESS)
#define IOCTL_SERIAL_SET_LINE_CONTROL   CTL_CODE(FILE_DEVICE_SERIAL_PORT, 3,METHOD_BUFFERED,FILE_ANY_ACCESS)
#define IOCTL_SERIAL_SET_BREAK_ON       CTL_CODE(FILE_DEVICE_SERIAL_PORT, 4,METHOD_BUFFERED,FILE_ANY_ACCESS)
#define IOCTL_SERIAL_SET_BREAK_OFF      CTL_CODE(FILE_DEVICE_SERIAL_PORT, 5,METHOD_BUFFERED,FILE_ANY_ACCESS)
#define IOCTL_SERIAL_IMMEDIATE_CHAR     CTL_CODE(FILE_DEVICE_SERIAL_PORT, 6,METHOD_BUFFERED,FILE_ANY_ACCESS)
#define IOCTL_SERIAL_SET_TIMEOUTS       CTL_CODE(FILE_DEVICE_SERIAL_PORT, 7,METHOD_BUFFERED,FILE_ANY_ACCESS)
#define IOCTL_SERIAL_GET_TIMEOUTS       CTL_CODE(FILE_DEVICE_SERIAL_PORT, 8,METHOD_BUFFERED,FILE_ANY_ACCESS)
#define IOCTL_SERIAL_SET_DTR            CTL_CODE(FILE_DEVICE_SERIAL_PORT, 9,METHOD_BUFFERED,FILE_ANY_ACCESS)
#define IOCTL_SERIAL_CLR_DTR            CTL_CODE(FILE_DEVICE_SERIAL_PORT,10,METHOD_BUFFERED,FILE_ANY_ACCESS)
#define IOCTL_SERIAL_RESET_DEVICE       CTL_CODE(FILE_DEVICE_SERIAL_PORT,11,METHOD_BUFFERED,FILE_ANY_ACCESS)
#define IOCTL_SERIAL_SET_RTS            CTL_CODE(FILE_DEVICE_SERIAL_PORT,12,METHOD_BUFFERED,FILE_ANY_ACCESS)
#define IOCTL_SERIAL_CLR_RTS            CTL_CODE(FILE_DEVICE_SERIAL_PORT,13,METHOD_BUFFERED,FILE_ANY_ACCESS)
#define IOCTL_SERIAL_SET_XOFF           CTL_CODE(FILE_DEVICE_SERIAL_PORT,14,METHOD_BUFFERED,FILE_ANY_ACCESS)
#define IOCTL_SERIAL_SET_XON            CTL_CODE(FILE_DEVICE_SERIAL_PORT,15,METHOD_BUFFERED,FILE_ANY_ACCESS)
#define IOCTL_SERIAL_GET_WAIT_MASK      CTL_CODE(FILE_DEVICE_SERIAL_PORT,16,METHOD_BUFFERED,FILE_ANY_ACCESS)
#define IOCTL_SERIAL_SET_WAIT_MASK      CTL_CODE(FILE_DEVICE_SERIAL_PORT,17,METHOD_BUFFERED,FILE_ANY_ACCESS)
#define IOCTL_SERIAL_WAIT_ON_MASK       CTL_CODE(FILE_DEVICE_SERIAL_PORT,18,METHOD_BUFFERED,FILE_ANY_ACCESS)
#define IOCTL_SERIAL_PURGE              CTL_CODE(FILE_DEVICE_SERIAL_PORT,19,METHOD_BUFFERED,FILE_ANY_ACCESS)
#define IOCTL_SERIAL_GET_BAUD_RATE      CTL_CODE(FILE_DEVICE_SERIAL_PORT,20,METHOD_BUFFERED,FILE_ANY_ACCESS)
#define IOCTL_SERIAL_GET_LINE_CONTROL   CTL_CODE(FILE_DEVICE_SERIAL_PORT,21,METHOD_BUFFERED,FILE_ANY_ACCESS)
#define IOCTL_SERIAL_GET_CHARS          CTL_CODE(FILE_DEVICE_SERIAL_PORT,22,METHOD_BUFFERED,FILE_ANY_ACCESS)
#define IOCTL_SERIAL_SET_CHARS          CTL_CODE(FILE_DEVICE_SERIAL_PORT,23,METHOD_BUFFERED,FILE_ANY_ACCESS)
#define IOCTL_SERIAL_GET_HANDFLOW       CTL_CODE(FILE_DEVICE_SERIAL_PORT,24,METHOD_BUFFERED,FILE_ANY_ACCESS)
#define IOCTL_SERIAL_SET_HANDFLOW       CTL_CODE(FILE_DEVICE_SERIAL_PORT,25,METHOD_BUFFERED,FILE_ANY_ACCESS)
#define IOCTL_SERIAL_GET_MODEMSTATUS    CTL_CODE(FILE_DEVICE_SERIAL_PORT,26,METHOD_BUFFERED,FILE_ANY_ACCESS)
#define IOCTL_SERIAL_GET_COMMSTATUS     CTL_CODE(FILE_DEVICE_SERIAL_PORT,27,METHOD_BUFFERED,FILE_ANY_ACCESS)
#define IOCTL_SERIAL_XOFF_COUNTER       CTL_CODE(FILE_DEVICE_SERIAL_PORT,28,METHOD_BUFFERED,FILE_ANY_ACCESS)
#define IOCTL_SERIAL_GET_PROPERTIES     CTL_CODE(FILE_DEVICE_SERIAL_PORT,29,METHOD_BUFFERED,FILE_ANY_ACCESS)
#define IOCTL_SERIAL_GET_DTRRTS         CTL_CODE(FILE_DEVICE_SERIAL_PORT,30,METHOD_BUFFERED,FILE_ANY_ACCESS)