unit1.cpp

本程序实现了串行端口的输入检测功能。采用getcommmodemstatus函数取得线路状态

//------------------------------------------------------------------

#include <vcl.h>
#pragma hdrstop

#include "Unit1.h"
//------------------------------------------------------------------
#pragma package(smart_init)
#pragma resource "*.dfm"
TForm1 *Form1;
HANDLE hComm; //将给串行端口使用的Handle声明
//------------------------------------------------------------------
__fastcall TForm1::TForm1(TComponent* Owner)
        : TForm(Owner)
{
}
//------------------------------------------------------------------

void __fastcall TForm1::Button2Click(TObject *Sender)
{
  if (hComm!=INVALID_HANDLE_VALUE) CloseHandle(hComm);
  exit(EXIT_SUCCESS);
}
//------------------------------------------------------------------
void __fastcall TForm1::Button1Click(TObject *Sender)
{
  char *ComNo;
  DCB dcb;
  String Temp;
  //取得要打开的通信端口
  Temp = "COM"+IntToStr(rdCOM->ItemIndex +1);
  //转换至指针类型Char
  ComNo = Temp.c_str();
  hComm = CreateFile(ComNo,GENERIC_READ | GENERIC_WRITE,
       0, NULL, OPEN_EXISTING, 0, 0);
  if (hComm == INVALID_HANDLE_VALUE) // 如果COM 未打开
  {
    MessageBox(0, "打开通信端口错误!!","Comm Error",MB_OK);
    return;
   }
  //将dcb地址传入，以取得通信参数
  GetCommState(hComm,&dcb);     // 得知目前COM 的状态
  dcb.BaudRate = CBR_9600;      // 设置波特率为9600
  dcb.ByteSize = 8;             // 字节为 8 bit
  dcb.Parity = NOPARITY;         // Parity 为 None
  dcb.StopBits = ONESTOPBIT;             // 1 个Stop bit
  //通信端口设置
  if (!SetCommState(hComm, &dcb)) {       // 设置COM 的状态
    MessageBox (0, "通信端口设置错误!!!","Set Error",MB_OK);
    CloseHandle(hComm);
    return;
   }
}
//------------------------------------------------------------------
void __fastcall TForm1::Timer1Timer(TObject *Sender)
{
  unsigned long lStatus;
  if (hComm == INVALID_HANDLE_VALUE) return;
  if (GetCommModemStatus(hComm,&lStatus))
   {
     //检查CTS状态
     if (lStatus & MS_CTS_ON)
      spCTS->Brush->Color =clRed;
     else spCTS->Brush->Color =clWhite;
     //检查DSR状态
     if (lStatus & MS_DSR_ON )
       spDSR->Brush->Color =clRed;
     else spDSR->Brush->Color =clWhite;
     //检查RI状态
     if ( lStatus & MS_RING_ON )
       spRI->Brush->Color =clRed;
     else spRI->Brush->Color =clWhite;
     //检查CD状态
     if ( lStatus & MS_RLSD_ON )
       spCD->Brush->Color =clRed ;
     else spCD->Brush->Color =clWhite;
     }
}
//------------------------------------------------------------------