serialdll.dpr

PC_COM串口通信

library serialDLL;

{ (c) ELEKTOR 2002                                      }
{ This library is used to make the use of the serial    }
{ ports in Windows more easy.                           }
{ Apart from all the standard functions, this DLL is    }
{ capable of sending a Windows-message to the           }
{ application if the status of the serial port is       }
{ changed. Therefore, polling the serial port is no     }
{ longer nessecary.                                     }


uses
  Windows,SysUtils,
  Classes,TreadUnit;
{ Threadunit contains the class which is responsible for}
{ waiting untill an event occurs on the serial port     }
{ and then sending a user-defined message to the appli- }
{ cation                                                }


var
  PortTimeout : _COMMTIMEOUTS;
  PortHandle : Integer;
  PortDCB : TDCB;
  PortNr  : Integer;
  PortState : Cardinal;

function OpenCOM (Port  : Integer):integer; stdcall;
{ This function opens the serial port, identified by the value of "Port"}
{ So, a value of 1 represents COM1, etc.                                }
begin
  if (PortHandle=0) then        {Check to see if the DLL has opened another port}
  begin                         { This library is only capable of handling 1    }
                                { serial port at a time.                        }
    PortHandle := CreateFile (PChar('COM'+IntToStr(Port)),
      GENERIC_READ or GENERIC_WRITE,0,nil,OPEN_EXISTING,FILE_ATTRIBUTE_NORMAL,Longint(0));
    if (PortHandle<>-1) then    {If opening did NOT fail, then                  }
    begin
      GetCommState (PortHandle,PortDCB);        { Necessary for WaitCommEvent,  }
      GetCommTimeouts (PortHandle,PortTimeout);
      PortTimeout.ReadIntervalTimeout:=1;
      PortTimeout.ReadTotalTimeoutMultiplier:=1;
      PortTimeout.ReadTotalTimeoutConstant:=1;
      SetCommState (PortHandle,PortDCB);
      if (SetCommTimeouts (PortHandle,PortTimeout)=True)
      then
        PortNr:=Port            {Store the nr. of the port, which just openend  }
      else
      begin

        PortNr:=0;              { If the programm failed to set the status of   }
        CloseHandle (PortHandle);{ the port, than opening has also failed.      }
                                { Make sure the port is closed, otherwise       }
                                { this port is blocked for other applications   }
      end;
    end
    else
    begin
      MessageBox (0,'CreateFile failed!','ERROR',MB_OK);
      PortNr:=0;                { Opening has failed. Use the var PortNr to in- }
                                { dicate that opening has failed.               }
    end;
  end;
  OpenCOM:=PortNr;              { Return the PortNr. This is 0 whenever an error}
  if (PortNr=0) then PortHandle:=0;{Also make the PortHandle 0 ,because this   }
                                { var is used througout the DLL to check wether }
                                { or not a serial port has been opened.         }
end;

function COMPortExists (port : integer):integer;stdcall;
{ Port identifies the serial port to check. If serial port does exist and is not}
{ in use by another programm, then return 0. Otherwise return 1}
var TestHandle : integer;
begin
  TestHandle := CreateFile (PChar('COM'+IntToStr(Port)),
    GENERIC_READ or GENERIC_WRITE,0,nil,OPEN_EXISTING,FILE_ATTRIBUTE_NORMAL,Longint(0));
  if (TestHandle=-1) then
  begin
    COMPortExists:=0;
  end
  else
  begin
    COMPortExists:=1;
    CloseHandle(TestHandle);    { ALWAYS close the port, so that it isn't       }
                                { blocked by windows                            }
  end;
end;

Procedure CloseCOM; stdcall;
begin
  SetCommMask (PortHandle,1); {Make sure that WaitCommEvent     }
  SetCommMask (PortHandle,0); {in the Thread returns!           }
  CloseHandle (PortHandle);   { And close the serial port       }
  PortHandle:=0;
end;

procedure SendCharCOM (ch : char);stdcall;
{ Send the character specified in ch to the serial port         }
var
  written  : cardinal;
begin
  if (PortHandle<>0) then
  begin
    WriteFile (PortHandle,ch,1,written,nil); { If character is [Carriage Ret]   }
    if (ch=chr(13)) then        { then insert [newline] as well.                }
    begin
      ch:=chr(10);
      WriteFile (PortHandle,ch,1,written,nil);
    end;
  end;
end;

function GetPortNr : Integer;stdcall;
{ Use this function which serial port is currently opened by the DLL.           }
{ If there is no port open, the function will return 0.                         }
begin
  GetPortNr:=PortNr;
end;

function IsPortOpen : Integer;stdcall;
{ Use this function to determine if a port is currently opened by the DLL       }
begin
  if (PortHandle=0) then IsPortOpen:=0 else IsPortOpen:=1;
end;

Procedure SetTxD; stdcall;
{This function sets the TxD-line of the serial port, but be cautious :          }
{If the TxD line is set, then the programm will crash when trying to send one   }
{or more characters through the serial port. To be able to use the TxD line to  }
{send, make sure the line is reset (using ResetTxD) prior to sending characters }
{throug the serial port.                                                        }
begin If (PortHandle<>0) then EscapeCommFunction(PortHandle,SETBREAK); end;

Procedure ResetTxD; stdcall;
begin if (PortHandle<>0) then EscapeCommFunction(PortHandle,CLRBREAK); end;

Procedure SetRTS; stdcall;
begin If (PortHandle<>0) then EscapeCommFunction (PortHandle,3); end;

Procedure ResetRTS;stdcall;
begin If (PortHandle<>0) then EscapeCommFunction (PortHandle,CLRRTS); end;

Procedure SetDTR; stdcall;
begin If (PortHandle<>0) then EscapeCommFunction (PortHandle,5); end;

Procedure ResetDTR;stdcall;
begin If (PortHandle<>0) then EscapeCommFunction (PortHandle,CLRDTR); end;

function GetHandle : integer;stdcall;
begin GetHandle:=PortHandle; end;

function GetCTS: integer;stdcall;
{Get the status of the CTS line                                                 }
begin
  If (PortHandle<>0) then
  begin
    GetCommModemStatus (PortHandle,PortState);
    if ((Portstate and MS_CTS_ON)<>0) then
      GetCTS:=1
    else
      GetCTS:=0;
  end
  else
    GetCTS:=0;
end;

function GetDCD: integer;stdcall;
{Get the status of the DCD line                                                 }
begin
  If (PortHandle<>0) then
  begin
    GetCommModemStatus (PortHandle,PortState);
    if ((Portstate and MS_RLSD_ON)<>0) then
      GetDCD:=1
    else
      GetDCD:=0;
  end
  else
    GetDCD:=0;
end;

function GetDSR: integer;stdcall;
{ Get the status of the DSR line                                                }
begin
  If (PortHandle<>0) then
  begin
    GetCommModemStatus (PortHandle,PortState);
    if ((Portstate and MS_DSR_ON)<>0) then
      GetDSR:=1
    else
      GetDSR:=0;
  end
  else
    GetDSR:=0;
end;
function GetRI: integer;stdcall;
{ Get the status of the RI line                                                 }
begin
  If (PortHandle<>0) then
  begin
    GetCommModemStatus (PortHandle,PortState);
    if ((Portstate and MS_RING_ON)<>0) then
      GetRI:=1
    else
      GetRI:=0;
  end
  else
    GetRI:=0;
end;

procedure CheckInputs (UserMessage:integer;ApHndl:HWND);stdcall;
{ Use this procedure to receive a Windowsmessage whenever the status of the     }
{ serial port is changed. This includes a change in the signal on DCD, DSR,CTS, }
{ a negative edge on the RxD line, a positive edge on the RI line and also      }
{ whenever a character is received or the transmit buffer runs empty.           }
begin
  if (PortHandle<>-1) then
  begin
  {Create the thread, which in turn sends a message when }
  {an event occurs on the Serial port}
    TSerialThread.Create(PortHandle,UserMessage,ApHndl);
  end;
end;

function BaudRateSet (baud:cardinal):Boolean;stdcall;
{ Set the baudrate of the serial port.                                          }
{ The cardinal baud can be any value, so use is not limited to the standard     }
{ baudrates. Not every serial interface supports all the possible baudrates.    }
{ Whenever the change in baudrate has failed, the function will return false to }
{ indicate that the baudrte has not been changed succesfully (the previous baud-}
{ rate is still in effect).                                                     }
begin
  GetCommState (PortHandle,PortDCB);
  PortDCB.BaudRate:=baud;
  BaudRateSet:=SetCommState (PortHandle,PortDCB);
end;

function ParitySet (par : byte):Boolean; stdcall;
{ Set the parity of the serial port.            }
{ possible values of par are :                  }
{                                               }
{  NOPARITY    (0)   : No parity                }                          
{  ODDPARITY   (1)   : Odd Parity               }
{  EVENPARITY  (2)   : Even Parity              }
{  MARKPARITY  (3)   : Mark Parity              }
{  SPACEPARITY (4)   : Space Parity             }
begin
  GetCommState (PortHandle,PortDCB);
  PortDCB.Parity:=Par;
  ParitySet:=SetCommState (PortHandle,PortDCB);
end;

function BitsPerByteSet (bpb : byte):Boolean; stdcall;
{ Set the number of bits per byte to send and receive.  }
{ Possible values of bpb are 4 to 8                     }

begin
  GetCommState (PortHandle,PortDCB);
  PortDCB.ByteSize:=bpb;
  BitsPerByteSet:=SetCommState (PortHandle,PortDCB);
end;

function StopBitsSet (stop : byte):Boolean; stdcall;
{ Set the number of stopbits                            }
{ Possible values for stop are :                        }
{ ONESTOPBIT    (0)  : 1 stop bit                       }
{ ONE5STOPBITS  (1)  : 1.5 stop bits                    }
{ TWOSTOPBITS   (2)  : 2 stop bits                      }

begin
  GetCommState (PortHandle,PortDCB);
  PortDCB.StopBits:=stop;
  StopBitsSet:=SetCommState (PortHandle,PortDCB);
end;

function ReadCharCOM (var kar:char):Boolean;stdcall;
{ Read a character from the serial port.                }
{ This function waits until it receives a character!    }

var
  didread :cardinal;
begin
  if (PortHandle<>-1) then
  begin
    ReadFile (PortHandle,kar,1,didread,nil);
  end;
  if (didread<>0) then ReadCharCOM:=True else ReadCharCOM:=false;
end;


{$R *.RES}
exports
  BaudRateSet,ParitySet,
  BitsPerByteSet,StopBitsSet,
  OpenCOM,CloseCOM,
  GetPortNr,IsPortOpen,
  COMPortExists,
  GetHandle,
  CheckInputs,
  GetCTS,GetDCD,
  GetDSR,GetRI,
  SetTxD,ResetTxD,
  SetRTS,ResetRTS,
  SetDTR,ResetDTR,
  SendCharCOM,REadCharCOM;

begin
  PortHandle:=0;
end.