опубликован 26-03-2001 11:26 MSK            

Monitoring Communications Events
The following example code opens the serial port for overlapped I/O, creates an event mask to monitor CTS and DSR signals, and then waits for an event to occur. The WaitCommEvent function should be executed as an overlapped operation so the other threads of the process cannot perform I/O operations during the wait.

HANDLE hCom;
OVERLAPPED o;
BOOL fSuccess;
DWORD dwEvtMask;

hCom = CreateFile( "COM1",
GENERIC_READ | GENERIC_WRITE,
0, // exclusive access
NULL, // no security attributes
OPEN_EXISTING,
FILE_FLAG_OVERLAPPED,
NULL
);

if (hCom == INVALID_HANDLE_VALUE)
{
// Handle the error.
}

// Set the event mask.

fSuccess = SetCommMask(hCom, EV_CTS | EV_DSR);

if (!fSuccess)
{
// Handle the error.
}

// Create an event object for use in WaitCommEvent.

o.hEvent = CreateEvent(
NULL, // no security attributes
FALSE, // auto reset event
FALSE, // not signaled
NULL // no name
);

assert(o.hEvent);

if (WaitCommEvent(hCom, &dwEvtMask, &o))
{
if (dwEvtMask & EV_DSR)
{
// To do.
}

if (dwEvtMask & EV_CTS)
{
// To do.
}
}

И еще пример

Configuring a Communications Resource
The following example opens a handle to COM1 and fills in a DCB structure with the current configuration. The DCB structure is then modified and used to reconfigure the device.

/* A sample program to illustrate setting up a serial port. */

#include <windows.h>

int
main(int argc, char *argv[])
{
DCB dcb;
HANDLE hCom;
BOOL fSuccess;
char *pcCommPort = "COM2";

hCom = CreateFile( pcCommPort,
GENERIC_READ | GENERIC_WRITE,
0, // comm devices must be opened w/exclusive-access
NULL, // no security attributes
OPEN_EXISTING, // comm devices must use OPEN_EXISTING
0, // not overlapped I/O
NULL // hTemplate must be NULL for comm devices
);

if (hCom == INVALID_HANDLE_VALUE) {
// Handle the error.
printf ("CreateFile failed with error %d.\n", GetLastError());
return (1);
}

// We will build on the current configuration, and skip setting the size
// of the input and output buffers with SetupComm.

fSuccess = GetCommState(hCom, &dcb);

if (!fSuccess) {
// Handle the error.
printf ("GetCommState failed with error %d.\n", GetLastError());
return (2);
}

// Fill in the DCB: baud=57,600 bps, 8 data bits, no parity, and 1 stop bit.

dcb.BaudRate = CBR_57600; // set the baud rate
dcb.ByteSize = 8; // data size, xmit, and rcv
dcb.Parity = NOPARITY; // no parity bit
dcb.StopBits = ONESTOPBIT; // one stop bit

fSuccess = SetCommState(hCom, &dcb);

if (!fSuccess) {
// Handle the error.
printf ("SetCommState failed with error %d.\n", GetLastError());
return (3);
}

printf ("Serial port %s successfully reconfigured.\n", pcCommPort);
return (0);
}