如何实现串口通讯(100分)

如何实现串口通讯

用串口通讯的控件就行了
mscomm
spcomm
或直接用api

可以用控件（spcomm,Mscomm等），也可以自己写
本人推荐：用Spcomm

可否介绍一些这方面的资料 thank you

USAGE
=====

To use the component once it is installed:
1) Attach an event handler to 'OnReceiveData'.
2) Call 'StartComm' to open the port.
3) Use the 'WriteCommData' method to write to the Comm port.
4) Call 'StopComm' to close the port.


PROPERTY
========

CommName : String

The name of comm port. The comm port is named 'COM1', 'COM2',...
This comm port must exist when you open it.

BaudRate : DWORD

The baud rate for this comm port. It must be a legal value for your
serial port can accept it.
You can change this value when the comm is open and
the real baud rate is changed immediately.

ParityCheck : Boolean

Specifies whether parity checking is enabled. If this member is TRUE,
parity checking is performed and errors are reported
(to OnReceiveError handler).
You can change this value when the comm is open.

Outx_CtsFlow : Boolean

Specifies whether the CTS (clear-to-send) signal is monitored
for output flow control. If this member is TRUE and CTS is turned off,
output is suspended until CTS is sent again.
CTS is a input pin. You can read its state from MSR register. It
usually connect to RTS pin in the other end.
It is often used for hardware flow control to indicate that the other
end if being waiting for data.
You can change this value when the comm is open.

CTS Input on | the other end is waiting for data
------------+----------------------------------------
Input off | the other end will NOT receive any data

Outx_DsrFlow : Boolean

Specifies whether the DSR (data-set-ready) signal is monitored for
output flow control. If this member is TRUE and DSR is turned off,
output is suspended until DSR is sent again.
DSR is a input pin. You can read its state from MSR register. It
usually connect to DTR pin in the other end.
It is often used for hardware flow control to indicate that the other
end is working(active, ready, wait for data...)
You can change this value when the comm is open.

DSR Input on | the other end is ready, and wait for your data
------------+----------------------------------------------------
Input off | the other end is not ready, we cannot send data out

DtrControl : ( DtrEnable, DtrDiable, DtrHandshake )

Specifies the DTR (data-terminal-ready) flow control. This member
can be one of the following values:

Value Meaning
------------- ------------------------------------------------------
DtrDiable Disables the DTR line when the device is
opened and leaves it disabled.
DtrEnable Enables the DTR line when the device is
opened and leaves it on.
DtrHandshake Enables DTR handshaking. When our comm port is opened
and ready for receiving data, DTR is enabled. When
our comm port is suspend, closed or has error
(and not cleared), DTR is disable.
If handshaking is enabled, it is an error for the
application to adjust the line by using the Win32
EscapeCommFunction function.

DTR is a output pin. You can set its state in MCR register.
It usually connect to DSR pin in the other end.
You can change this value when the comm is open.

DsrSensitivity : Boolean;

Specifies whether the communications driver is sensitive to the
state of the DSR signal. If this member is TRUE, the driver ignores
any bytes received, unless the DSR modem input line is high.
You can change this value when the comm is open.

TRUE | ignore any received byte
-------+------------------------------
FALSE | nothing

TxContinueOnXoff : Boolean;

Specifies whether transmission stops when the input buffer is full
and the driver has transmitted the XoffChar character. If this member
is TRUE, transmission continues after the input buffer has come within
XoffLim bytes of being full and the driver has transmitted the
XoffChar character to stop receiving bytes. If this member is FALSE,
transmission does not continue until the input buffer is within XonLim
bytes of being empty and the driver has transmitted the XonChar
character to resume reception.
You can change this value when the comm is open.

TRUE | enable or disable transmisstion has no any relation with
| input buffer
-------+-------------------------------------------------------------
FALSE | When Xoff is send(input buffer will be full),stop transmission.
| And stop continue until Xon is send(input buffer will empty).

Outx_XonXoffFlow : Boolean

Specifies whether XON/XOFF flow control is used during transmission.
If this member is TRUE, transmission stops when the XoffChar character
is received and starts again when the XonChar character is received.
You can change this value when the comm is open.

Action | Xoff received | Xon received
--------+--------------------+---------------------------
TRUE | stop transmission | resume transmission
| discard Xoff char | discard Xon char
--------+--------------------+------------------------------
FALSE | read in Xoff char | read in Xon char

Inx_XonXoffFlow : Boolean

Specifies whether XON/XOFF flow control is used during reception.
If this member is TRUE, the XoffChar character is sent when the
input buffer comes within XoffLim bytes of being full, and the
XonChar character is sent when the input buffer comes within XonLim
bytes of being empty.
You can change this value when the comm is open.

| input buffer comes within
+-----------------------------+------------------------------
Action | XoffLim bytes of being full | XonLim bytes of being empty
--------+-----------------------------+------------------------------
TRUE | Xoff char send | Xon char send
--------+-----------------------------+------------------------------
FALSE | do nothing | do nothing

ReplaceWhenParityError : Boolean

Specifies whether bytes received with parity errors are replaced with
the character specified by the ReplacedChar member. If this member is
TRUE and the ParityCheck member is TRUE, replacement occurs.
You can change this value when the comm is open.

IgnoreNullChar : Boolean

Specifies whether null bytes are discarded. If this member is TRUE,
null bytes are discarded when received.
You can change this value when the comm is open.

RtsControl : ( RtsEnable, RtsDiable, RtsHandshake, TransmissionAvailableControl );

Specifies the RTS (request-to-send) flow control. If this value is zero, the default is RTS_CONTROL_HANDSHAKE. This member can be one of the following values:

Value Meaning
------------------ -------------------------------------------------
RtsDiable Disables the RTS line when the device
is opened and leaves it disabled.
RtsEnable Enables the RTS line when the device
is opened and leaves it on.
RtsHandshake Enables RTS handshaking. The driver raises the
RTS line when the "type-ahead" (input) buffer is
less than one-half full and lowers the RTS line
when the buffer is more than three-quarters full.
If handshaking is enabled, it is an error for the
application to adjust the line by using the
Win32 EscapeCommFunction function.

input buffer | less than 1/2 full | more than 3/4 full
--------------+--------------------+--------------------
RTS | output set | output clear

TransmissionAvailable
Specifies that the RTS line will be enabled
if bytes are available for transmission. After
all buffered bytes have been sent, the RTS line
will be disable.

output buffer | have available byte | no any data
---------------+---------------------+-----------------
RTS | output set | output clear

RTS is a output pin. You can set its state in MCR register.
It usually connect to CTS pin in the other end.
You can change this value when the comm is open.

XonLimit : WORD

Specifies the minimum number of bytes allowed in the input buffer
before the XON character is sent.
You can change this value when the comm is open.

Example:
The size of input buffer is 1000 bytes and XonLimit is 100.
And XOff character have sent before.
When bytes in input buffer from 101 to 100, the Xon character is
sent.

XoffLimit : WORD

Specifies the maximum number of bytes allowed in the input buffer
before the XOFF character is sent. The maximum number of bytes
allowed is calculated by subtracting this value from the size,
in bytes, of the input buffer.
You can change this value when the comm is open.

Example:
The size of input buffer is 1000 bytes and XonLimit is 100.
When bytes in input buffer from 899 to 900, the Xoff character is
sent.

ByteSize : ( _5, _6, _7, _8 )

Specifies the number of bits in the bytes transmitted and received.
You can change this value when the comm is open.

Parity : ( None, Odd, Even, Mark, Space )

Specifies the parity scheme to be used. This member can be one of the
following values:

Value Meaning
------- ---------------------
None No parity
Odd Sum of logic '1' bits (data bits and parity bit) is odd
Even Sum of logic '1' bits (data bits and parity bit) is even
Mask Parity bit is always in logic '1'
Space Parity bit is always in logic '0'

You can change this value when the comm is open.


StopBits : ( _1, _1_5, _2 )

Specifies the number of stop bits to be used.
You can change this value when the comm is open.

XonChar : AnsiChar

Specifies the value of the XON character for both transmission and
reception.
You can change this value when the comm is open.

XoffChar : AnsiChar

Specifies the value of the XOFF character for both transmission and
reception.
You can change this value when the comm is open.

ReplacedChar : AnsiChar

Specifies the value of the character used to replace bytes received
with a parity error when ReplaceWhenParityError member is TRUE and
ParityCheck member is TRUE.
You can change this value when the comm is open.

Handle : THandle <read-only>

The comm file handle. Get from 'CreateFile' function in 'StartComm'.
You can use it for another Win32 COMM API operation

SendDataEmpty : Boolean <run-time &amp; read-only>

True when send-buffer is empty and no any pending send require in message
queue. False if send-buffer is not empty or have send require in message
queue.

METHOD
======

procedure StartComm

Start a communication for this comm port.
If failure, raise ECommsError exception and ECommsError.Message contain
following string:
'This serial port already opened'
'Error opening serial port'
'File handle is not a comm handle'
'Cannot setup comm buffer'
'Unable to create event'
'Unable to create read thread'
'Unable to create write thread'

procedure StopComm

Stop and end all communication threads for this comm port.
No any return.

function WriteCommData( pDataToWrite: PChar;
dwSizeofDataToWrite: Word ): Boolean

Send a String to the Write Thread to be written to the Comm.
This subroutine will return immediately. The send operation will
do in background.
Parameters:
pszStringToWrite - string to Write to Comm port.
nSizeofStringToWrite - length of pszStringToWrite.
Return:
TRUE : if the PostMessage to write thread is successful.
FALSE: if PostMessage fails or Write thread doesn't exist.

function GetModemState : DWORD;

Get and return the modem state right now. They are the state of modem
input pin from MSR.
The return value can be one or more of the following codes:

Value Meaning
---------- -----------------------------------------------------------
MS_CTS_ON The CTS (clear-to-send) signal is on.
MS_DSR_ON The DSR (data-set-ready) signal is on.
MS_RING_ON The ring indicator signal is on.
MS_RLSD_ON The RLSD (receive-line-signal-detect) signal is on.

The function fails if the hardware does not support the
control-register values.

EVENT HANDLER
=============

OnReceiveData : procedure (Sender: TObject;
Buffer: Pointer;
BufferLength: Word) of object

When
1. The input buffer contains received data and
2. more than a limit size or
3. read time-out
the event handler is called
Sender : point to TComm object which raise this call
Buffer : the buffer which contains received data
BufferLength : the size of received data in Buffer

OnReceiveError : procedure(Sender: TObject; EventMask : DWORD) of object

When error happend during receiving, the event handler is called.
Sender : point to TComm object which raise this call
EventMask : the value get from ClearCommError in 'HandleCommEvent'
A 32-bit variable to be filled with a mask indicating the
type of error. This parameter can be one or more of the
following error codes:

Value Meaning
---------- -----------------------------------------------------------
CE_BREAK The hardware detected a break condition. (no support now)
CE_DNS Windows 95 only: A parallel device is not selected.
CE_FRAME The hardware detected a framing error.
CE_IOE An I/O error occurred during communications with the device.
CE_MODE The requested mode is not supported, or the hFile parameter
is invalid. If this value is specified, it is the only
valid error.
CE_OOP Windows 95 only: A parallel device signaled that it is out
of paper.
CE_OVERRUN A character-buffer overrun has occurred. The next character
is lost.
CE_PTO Windows 95 only: A time-out occurred on a parallel device.
CE_RXOVER An input buffer overflow has occurred. There is either no
room in the input buffer, or a character was received after
the end-of-file (EOF) character.
(second condition is impossible happened under Win32)
CE_RXPARITY The hardware detected a parity error. (no support)
CE_TXFULL The application tried to transmit a character, but the
output buffer was full. (no support)


OnRequestHangup: procedure(Sender: TObject) of object;

When the program is terminated abnormally, the event handler is
called.

OnModemStateChange : procedure(Sender: TObject; ModemEvent : DWORD) of object

When Modem's RLSD(CD) change state (HIGH<->LOW) or the ring indicator
signal is detected, this event handler is
called.
Sender : point to TComm object which raise this call
ModemEvent : A 32-bit variable to be filled with a mask indicating
what made this call. This parameter can be one or more
of the following codes:

Value Meaning
---------- -----------------------------------------------------------
ME_CTS The CTS (clear-to-send) signal has changed state.
(support in future, not support now)
ME_DSR The DSR (data-set-ready) signal has changed state.
(support in future, not support now)
ME_RING The ring indicator signal was detected.
ME_RLSD The RLSD (receive-line-signal-detect) signal has changed
state.

推荐用spcomm，可以看看他们的帮助，还有范例。
简单的因该可以搞定。
有本书也不错，delphi串口通讯编程 建议看看

如果你是想学串口通讯编程，最好别用什么第三方控件，直接用API或ClientSocket和serverSocket
这样对你有好处，关于ClientSocket和serverSocket的使用，在delphi的demo目录下的chat下有
一个聊天程序，可以看看。
别让人感觉学Delphi的人就会用控件

转帖，希望有用

SPCOMM RS-232多线程控件例子：现时DELPHI上有很多串行口控件，SPCOMM控件有Data Bits、Parity、 Stop Bits 等配置，支持 Read/Write 时序控制 (Timing control)、 ReadIntervalTimeout、 WriteIntervalTimout 等 ，支持 DTR/DSR, RTS/CTS 硬件流程控置及 Xon/Xoff 软件流程控置，是目前比较完善的控件。 以下是一个用RS-232进行数据接收、显示的例子。必须将RS232的通信参数设置好才能正确接收数据。（Data Bits,Parity,Stop Bits,COM口参数）
unit Unit1;
interface
uses
Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
StdCtrls, SPComm;
type
TForm1 = class(TForm)
Comm1: TComm;
Memo1: TMemo;
procedure Comm1ReceiveData(Sender: TObject; Buffer: Pointer;
BufferLength: Word);
procedure FormCreate(Sender: TObject);
procedure FormClose(Sender: TObject; var Action: TCloseAction);
private
{ Private declarations }
public
{ Public declarations }
end;
var
Form1: TForm1;
implementation
{$R *.DFM}
procedure TForm1.Comm1ReceiveData(Sender: TObject; Buffer: Pointer;
BufferLength: Word);
var
s: string;
begin
SetLength(S, BufferLength); //接收RS232的数据并显示Memo1上。
Move(Buffer^, PChar(S)^, BufferLength);
Memo1.Lines.Add(S);
Memo1.Invalidate;
end;
procedure TForm1.FormCreate(Sender: TObject);
begin
Comm1.startcomm;//创建窗体时，将comm1控件打开。
end;
procedure TForm1.FormClose(Sender: TObject; var Action: TCloseAction);
begin
comm1.StopComm;//关闭窗体时，将comm1控件关闭。
end;
end.

接受答案了.