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Does someone can give me an example how to open your com port with createfile and how to read and write to that??
Just call CreateFile, ReadFile and WriteFile. The docs on CreateFile specify how ports should be opened, and I suppose reading/writing COM ports is the same as reading/writing normal files.
I think you''ve mistitled your question. It''s too easy to read COM as "Component Object" rather than "Serial Communications Port" - at any rate - here''s some code for you.
//***************************************************************// From the book "Win32 System Services: The Heart of Windows 98// and Windows 2000"// by Marshall Brain// Published by Prentice Hall//// Copyright 1995, by Prentice Hall.//// This code demonstrates an extremely simple serial connection.//***************************************************************// commtest.cpp#include <windows.h>#include <stdio.h>void ErrorHandler(char *s, DWORD err){ fprintf(stderr,"%s\n", s); fprintf(stderr,"Error number: %s\n", err); ExitProcess(1);}void main(){ HANDLE comHandle; BOOL success; DCB dcb; char str[100]; DWORD numWrite, numRead; COMMTIMEOUTS timeouts; // Open the comm port. Can open COM, LPT, // or \\\\.\\TELNET comHandle = CreateFile("COM2" , GENERIC_READ|GENERIC_WRITE , 0, 0 , OPEN_EXISTING , FILE_ATTRIBUTE_NORMAL , 0); if ( comHandle == INVALID_HANDLE_VALUE ) { ErrorHandler("In CreateFile", GetLastError()); } // Get the current settings of the COMM port success = GetCommState(comHandle, &dcb); if ( !success ) { ErrorHandler("In GetCommState", GetLastError()); } // Modify the baud rate, etc. dcb.BaudRate = 2400; dcb.ByteSize = 8; dcb.Parity = NOPARITY; dcb.StopBits = ONESTOPBIT; // Apply the new comm port settings success = SetCommState(comHandle, &dcb); if ( !success ) { ErrorHandler("In SetCommState", GetLastError()); } // Change the ReadIntervalTimeout so that // ReadFile will return immediately. See // help file timeouts.ReadIntervalTimeout = MAXDWORD; timeouts.ReadTotalTimeoutMultiplier = 0; timeouts.ReadTotalTimeoutConstant = 0; timeouts.WriteTotalTimeoutMultiplier = 0; timeouts.WriteTotalTimeoutConstant = 0; SetCommTimeouts( comHandle, &timeouts ); // Set the Data Terminal Ready line EscapeCommFunction(comHandle, SETDTR); // Send an "at" command to the modem // Be sure to use \r rather than \n strcpy(str, "at\r"); success = WriteFile(comHandle , str , strlen(str) , &numWrite , 0); if ( !success ) { ErrorHandler("In WriteFile", GetLastError()); } // Wait 2 seconds and then retrieve from the // modem Sleep(2000); success = ReadFile(comHandle, str, 100, &numRead, 0); if ( !success ) { ErrorHandler("In ReadFile", GetLastError()); } // Print the string received fprintf(stdout,"%d\n", numRead); str[numRead]=''\0''; fprintf(stdout, "%s\n", str); // Clear the DTR line EscapeCommFunction(comHandle, CLRDTR); CloseHandle(comHandle);} This topic is closed to new replies.
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