我是串行编程的菜鸟。我正在尝试用 C 编写一个被动监视器，该监视器显示屏幕上写入或读取 COM 端口的任何内容。我见过的大部分代码实际上都是从 COM 端口读取或写入。
我试图从一个正在传输和接收 Modbus 流量的 COM 端口读取数据，但我没有得到任何读数。我正在使用 com0com 串口模拟器。只有当我真正从与 COM 端口配对的另一个端口读取时，代码才会起作用。
我正在尝试模仿串行端口监视器应用程序。到目前为止，它不起作用。请协助。
谢谢。
下面是 COM 读取的代码：
#include <stdio.h>
#include <stdlib.h>
#include <windows.h>
void setupPort(HANDLE * handle, char * portName);
void readFromPort(HANDLE * handle);
int main()
{
HANDLE first_port;
char * first_port_name = "COM3";
setupPort(&first_port, first_port_name);
readFromPort(&first_port);
return 0;
}
void setupPort(HANDLE * handle, char * portName)
{
BOOL status;
*handle = CreateFile(portName, //port name
GENERIC_READ | GENERIC_WRITE, //Read/Write
0, // No Sharing
NULL, // No Security
OPEN_EXISTING,// Open existing port only
0, // Non Overlapped I/O
NULL); // Null for Comm Devices
if (handle == INVALID_HANDLE_VALUE)
{
printf("\n%s could not be opened\n", portName);
}
else
{
printf("\n%s successfully opened.\n", portName);
}
DCB dcbSerialParams = { 0 }; // Initializing DCB structure
dcbSerialParams.DCBlength = sizeof(dcbSerialParams);
status = GetCommState(*handle, &dcbSerialParams); //retreives the current settings
if (status == FALSE)
printf("\n Error! in GetCommState()");
dcbSerialParams.BaudRate = CBR_9600; // Setting BaudRate = 9600
dcbSerialParams.ByteSize = 8; // Setting ByteSize = 8
dcbSerialParams.StopBits = ONESTOPBIT; // Setting StopBits = 1
dcbSerialParams.Parity = NOPARITY; // Setting Parity = None
status = SetCommState(*handle, &dcbSerialParams); //Configuring the port according to settings in DCB
if (status == FALSE)
{
printf("\n Error! in Setting DCB Structure");
}
else //If Successful display the contents of the DCB Structure
{
printf("\n\n Setting DCB Structure Successful\n");
printf("\n Baudrate = %d", dcbSerialParams.BaudRate);
printf("\n ByteSize = %d", dcbSerialParams.ByteSize);
printf("\n StopBits = %d", dcbSerialParams.StopBits);
printf("\n Parity = %d", dcbSerialParams.Parity);
}
/*------------------------------------ Setting Timeouts --------------------------------------------------*/
COMMTIMEOUTS timeouts = { 0 };
timeouts.ReadIntervalTimeout = 50;
timeouts.ReadTotalTimeoutConstant = 50;
timeouts.ReadTotalTimeoutMultiplier = 10;
timeouts.WriteTotalTimeoutConstant = 50;
timeouts.WriteTotalTimeoutMultiplier = 10;
if (SetCommTimeouts(*handle, &timeouts) == FALSE)
printf("\n\n Error! in Setting Time Outs");
else
printf("\n\n Setting Serial Port Timeouts Successful");
/*------------------------------------ Setting Receive Mask ----------------------------------------------*/
status = SetCommMask(*handle, EV_RXCHAR); //Configure Windows to Monitor the serial device for Character Reception
if (status == FALSE)
printf("\n\n Error! in Setting CommMask");
else
printf("\n\n Setting CommMask successful");
}
void readFromPort(HANDLE * handle)
{
BOOL status;
DWORD dwEventMask; // Event mask to trigger
char TempChar; // Temporary Character
char SerialBuffer[256]; // Buffer Containing Rxed Data
DWORD NoBytesRead; // Bytes read by ReadFile()
int i = 0;
/*------------------------------------ Setting WaitComm() Event ----------------------------------------*/
while(TRUE)
{
printf("\n\n Waiting for Data Reception");
status = TRUE; //Wait for the character to be received
/*-------------------------- Program will Wait here till a Character is received ------------------------*/
if (status == FALSE)
{
printf("\n Error! in Setting WaitCommEvent()");
}
else //If WaitCommEvent()==True Read the RXed data using ReadFile();
{
printf("\n\n Characters Received\n");
do
{
status = ReadFile(*handle, &TempChar, sizeof(TempChar), &NoBytesRead, NULL);
SerialBuffer[i] = TempChar;
i++;
}
while (NoBytesRead > 0);
/*------------Printing the RXed String to Console----------------------*/
printf("\n\n ");
int j =0;
for (j = 0; j < i-1; j++) // j < i-1 to remove the dupliated last character
{
printf("%02X", (unsigned int)(unsigned char)SerialBuffer[j]);
}
i=0;
}
//CloseHandle(*handle);//Closing the Serial Port
printf("\n +==========================================+\n");
}
}