modbus协议_PC实现.doc

modbus协议PC端的实现我使用C+ Builder 6.0调用Win32 API实现的。首先开一个线程。void _fastcall TForm1:FormCreate(TObject *Sender)ReadComm =new TRead232(true);ReadComm-FreeOnTerminate = true; 通过一个按钮实现打开/关闭串口void _fastcall TForm1:Button1Click(TObject *Sender) if(Button1-Caption = 打开通讯端口) /按钮名称是打开通讯端口？ char *ComNo; DCB dcb; String Temp; Temp = COM+IntToStr(rdCom-ItemIndex+1);/ TRadioGroup *rdCom; 定义要选择的串口 ComNo = Temp.c_str(); hComm =CreateFile(ComNo,GENERIC_READ|GENERIC_WRITE, 0,NULL,OPEN_EXISTING,0,0); if(hComm = INVALID_HANDLE_VALUE) MessageBox(0,打开串口失败!,Set Error,MB_OK); return; GetCommState(hComm,&dcb); dcb.BaudRate = CBR_9600; dcb.ByteSize = 8; dcb.Parity = NOPARITY; dcb.StopBits = ONESTOPBIT; if(!SetCommState(hComm,&dcb) MessageBox(0,打通讯端口设置错误!,Set Error,MB_OK); CloseHandle(hComm); return; Timer1-Enabled = True; Button1-Caption = 关闭串口; Shape1-Brush-Color = clRed; /启动接收线程 ReadComm-Resume(); else Button1-Caption = 打开通讯端口; CloseHandle(hComm); Shape1-Brush-Color = clBlack; Timer1-Enabled = False; ReadComm-Terminate(); 接收由线程TRead232完成void _fastcall TRead232:Execute()SetName();/- Place thread code here -if(!Terminated) Synchronize(ReadData);/-void _fastcall TRead232:ReadData()Form1-Caption = Updated in a thread;String Temp;char inbuff1024;DWORD nBytesRead,dwEvent,dwError;COMSTAT cs;if(hComm = INVALID_HANDLE_VALUE)MessageBox(0,串口失败!,Set Error,MB_OK);return;ClearCommError(hComm,&dwError,&cs);Form1-Edit1-Text = cs.cbInQue;if(cs.cbInQue sizeof(inbuff)PurgeComm(hComm,PURGE_RXCLEAR); return; ReadFile(hComm,inbuff,cs.cbInQue,&nBytesRead,NULL); inbuffcs.cbInQue=0; Form1-Memo1-Text =Form1-Memo1-Text+inbuff;发送是定时器TIMER1触发，定时发送的。void _fastcall TForm1:Timer1Timer(TObject *Sender)char SendData20;byte ch;int i;unsigned long lrc,BS;if (hComm=0) return;SendData0 = 0x41;SendData1 = 0x03;SendData2 = 0x00;SendData3 = 0x01;SendData4 = 0x00;SendData5 = 0x04;SendData6 = 0x1b;SendData7 = 0x09;SendData8 = 0;/ BS = 8; / StrLen(S