求助：串口编程用到线程时，CPU使用率达到100％，怎么解决？（在线等待）

[xjb258]

源代码如下：

//---------------------------------------------------------------------------
#include <vcl.h>
#pragma hdrstop
#include "Unit2.h"
#include "Unit1.h"
#pragma package(smart_init)
extern HANDLE hComm;
//---------------------------------------------------------------------------
// Important: Methods and properties of objects in VCL can only be
// used in a method called using Synchronize, for example:
//
// Synchronize(UpdateCaption);
//
// where UpdateCaption could look like:
//
// void __fastcall Unit2::UpdateCaption()
// {
// Form1->Caption = "Updated in a thread";
// }
//---------------------------------------------------------------------------
__fastcall TReadThread::TReadThread(bool CreateSuspended)
: TThread(CreateSuspended)
{
}
//---------------------------------------------------------------------------
void __fastcall TReadThread::Execute()
{ //---- Place thread code here ----
while (! Terminated)
Synchronize(ReadData);
}
//---------------------------------------------------------------------------
void __fastcall TReadThread::ReadData()
{
String Temp;
char inbuff[1024];
DWORD nBytesRead, dwEvent,dwTrans,dwError;
COMSTAT cs;
if (hComm == INVALID_HANDLE_VALUE)
return;

ClearCommError(hComm,&dwError,&cs); //取得状态

if (cs.cbInQue > sizeof(inbuff)) // 数据是否大于我们所准备的Buffer
{ PurgeComm(hComm, PURGE_RXCLEAR); // 清除COM 数据
return;
}
ReadFile(hComm,inbuff,cs.cbInQue,&nBytesRead,NULL); // 接收COM 的数据

inbuff[cs.cbInQue]= '\0'; // 转移数据到变量中

if (strlen(inbuff)>0) // 将数据显示在Memo1上
Form1->mReceive->Text = Form1->mReceive->Text + inbuff;
}
//--------------------------------------------------------------------------

[bjwf01]

请检查其他程序是否占用了串口，例如安装了调制解调器。

[kataboy]

楼主，我有一个建议，不知道有道理否？
我觉得你这样子做与不用线程是一样的效果，所以我觉得你没有必要用线程要是你想用线程最好改成以后的，同时解决100%CPU占用率：

源代码如下：

//---------------------------------------------------------------------------
#include <vcl.h>
#pragma hdrstop
#include "Unit2.h"
#include "Unit1.h"
#pragma package(smart_init)
extern HANDLE hComm;
//---------------------------------------------------------------------------
// Important: Methods and properties of objects in VCL can only be
// used in a method called using Synchronize, for example:
//
// Synchronize(UpdateCaption);
//
// where UpdateCaption could look like:
//
// void __fastcall Unit2::UpdateCaption()
// {
// Form1->Caption = "Updated in a thread";
// }
//---------------------------------------------------------------------------
__fastcall TReadThread::TReadThread(bool CreateSuspended)
: TThread(CreateSuspended)
{
}
//---------------------------------------------------------------------------
void __fastcall TReadThread::Execute()
{ //---- Place thread code here ----
while (! Terminated) {

String Temp;
char inbuff[1024];
DWORD nBytesRead, dwEvent,dwTrans,dwError;
COMSTAT cs;
if (hComm == INVALID_HANDLE_VALUE)
return;

ClearCommError(hComm,&dwError,&cs); //取得状态

if (cs.cbInQue > sizeof(inbuff)) // 数据是否大于我们所准备的Buffer
{ PurgeComm(hComm, PURGE_RXCLEAR); // 清除COM 数据
return;
}
ReadFile(hComm,inbuff,cs.cbInQue,&nBytesRead,NULL); // 接收COM 的数据

inbuff[cs.cbInQue]= '\0'; // 转移数据到变量中

if (strlen(inbuff)>0) // 将数据显示在Memo1上
Synchronize(ReadData);
Sleep(100);//加上这句可以不让CPU占用100%
}
}
//---------------------------------------------------------------------------
void __fastcall TReadThread::ReadData()
{
Form1->mReceive->Text = Form1->mReceive->Text + inbuff;
}
//--------------------------------------------------------------------------


当然，你要想做到最好，当然是用事件来做。就是说先创建一个事件，然后调用waitXXXX系列函数!
^_^

[hainanb]

gz

[r302t]

最好看一下关于串口方面的书，我的印象中好象要加串口等待函数，设置中断事件。

[solares1]

gz