请问一下 在做串口通信的时候，如何获取当前发送或接收缓冲区的大小？

[saver_gao]

如题：
在做串口通信的时候，比如： 当我往串口里面发送很多条数据的数据的时候，当缓冲区的数据全部被取走的时候，我再继续发送？请问一下，我怎么知道缓冲区里面数据还剩下有多少个字节啊？

[saver_gao]

路过的也帮忙顶一下 啊。。

[Storm2008]

BOOL ClearCommError(
  HANDLE hFile,     // handle to communications device
  LPDWORD lpErrors, // error codes
  LPCOMSTAT lpStat  // communications status
);


typedef struct _COMSTAT { 
  DWORD fCtsHold : 1; 
  DWORD fDsrHold : 1; 
  DWORD fRlsdHold : 1; 
  DWORD fXoffHold : 1; 
  DWORD fXoffSent : 1; 
  DWORD fEof : 1; 
  DWORD fTxim : 1; 
  DWORD fReserved : 25; 
  DWORD cbInQue; 
  DWORD cbOutQue; 
} COMSTAT, *LPCOMSTAT; 

cbInQue
Number of bytes received by the serial provider but not yet read by a ReadFile operation.
cbOutQue
Number of bytes of user data remaining to be transmitted for all write operations. This value will be zero for a nonoverlapped write.

[Storm2008]

BOOL ClearCommError(
HANDLE hFile, // handle to communications device
LPDWORD lpErrors, // error codes
LPCOMSTAT lpStat // communications status
);



COMSTAT
The COMSTAT structure contains information about a communications device. This structure is filled by the ClearCommError function.

typedef struct _COMSTAT {
DWORD fCtsHold : 1;
DWORD fDsrHold : 1;
DWORD fRlsdHold : 1;
DWORD fXoffHold : 1;
DWORD fXoffSent : 1;
DWORD fEof : 1;
DWORD fTxim : 1;
DWORD fReserved : 25;
DWORD cbInQue;
DWORD cbOutQue;
} COMSTAT, *LPCOMSTAT;



cbInQue
Number of bytes received by the serial provider but not yet read by a ReadFile operation.
cbOutQue
Number of bytes of user data remaining to be transmitted for all write operations. This value will be zero for a nonoverlapped write.

调用ClearCommError获得当前串口状态，cbInQue和cbOutQue 就是你想要的

[Storm2008]

procedure TForm1.tmReceiveTimer(Sender: TObject);
var
  Temp : String;
  inbuff : array[0..2047] of Char;
  nBytesRead, dwError : DWORD;
  cs : TCOMSTAT;
begin
  ClearCommError(hComm, dwError, @cs);
  //若未接收到数据或者接收的数据大于缓冲区大小责推出
  if cs.cbInQue = 0 then Exit;
  if cs.cbInQue > sizeof(inbuff) then
    begin
      PurgeComm(hComm, PURGE_RXCLEAR);
      Exit;
    end;

  ReadFile(hComm, inbuff, cs.cbInQue, nBytesRead, nil);
  Temp := Copy(inbuff, 1, cs.cbInQue);
  mReceive.Text := mReceive.Text + Temp;
  //将memo组件的显示位置移到最下端
  mReceive.SetFocus;
  mReceive.SelStart := Length(mReceive.Text);
  mReceive.SelLength := 0;

end;

[Storm2008]

if cs.cbInQue = 0 then Exit;
if cs.cbInQue > sizeof(inbuff) then

//---------------------------------------------------//
这两句是
if cs.cbInQue = 0 then Exit;
if cs.cbInQue > sizeof(inbuff) then
我想弄成红色的，结果成那样了

[saver_gao]

谢谢了，结贴。

[mypiip]

[Quote=引用 4 楼 Storm2008 的回复:]
Delphi(Pascal) codeprocedureTForm1.tmReceiveTimer(Sender: TObject);varTemp : String;
inbuff :array[0..2047]ofChar;
nBytesRead, dwError : DWORD;
cs : TCOMSTAT;beginClearCommError(hComm, dwError, @cs);//若未接收到数据或者接收的数据大于缓冲区大小责推出
ifcs.cbInQue=0thenExit;ifcs.cbInQue>sizeof(inbuff)thenbeginPurgeComm(hComm, PURGE_RXCLEAR);
Exit;end;

ReadFi…
[/Quote]
为什么俺引用了这个接收过程，却什么都收不到，cbInQue总是为0

[Storm2008]

[Quote=引用 7 楼 mypiip 的回复:]
引用 4 楼 Storm2008 的回复:
Delphi(Pascal) codeprocedureTForm1.tmReceiveTimer(Sender: TObject);varTemp : String;
inbuff :array[0..2047]ofChar;
nBytesRead, dwError : DWORD;
cs : TCOMSTAT;beginClearCommError(hComm, dwError, @cs);//若未接收到数据或者接收的数据大于缓冲区大小责推出
ifcs.cbInQue=0thenExit;ifcs.cbInQue>sizeof(inbuff)thenbeginPurgeComm(hComm, PURGE_RXCLEAR);
Exi…
[/Quote]


应该是你没收到什么数据
先用串口调试助手一类的软件看看能不能正常接受到数据
再看看你的串口设置

[gxw145]

?????