COMSTAT
The COMSTAT structure contains information about a communications device. This structure is filled by the ClearCommError function.
typedef struct _COMSTAT {
DWORD fCtsHold : 1; // Tx waiting for CTS signal
DWORD fDsrHold : 1; // Tx waiting for DSR signal
DWORD fRlsdHold : 1; // Tx waiting for RLSD signal
DWORD fXoffHold : 1; // Tx waiting, XOFF char received
DWORD fXoffSent : 1; // Tx waiting, XOFF char sent
DWORD fEof : 1; // EOF character sent
DWORD fTxim : 1; // character waiting for Tx
DWORD fReserved : 25; // reserved
DWORD cbInQue; // bytes in input buffer
DWORD cbOutQue; // bytes in output buffer
} COMSTAT, *LPCOMSTAT;
Members
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fCtsHold
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Specifies whether transmission is waiting for the CTS (clear-to-send) signal to be sent. If this member is TRUE, transmission is waiting.
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fDsrHold
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Specifies whether transmission is waiting for the DSR (data-set-ready) signal to be sent. If this member is TRUE, transmission is waiting.
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fRlsdHold
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Specifies whether transmission is waiting for the RLSD (receive-line-signal-detect) signal to be sent. If this member is TRUE, transmission is waiting.
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fXoffHold
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Specifies whether transmission is waiting because the XOFF character was received. If this member is TRUE, transmission is waiting.
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fXoffSent
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Specifies whether transmission is waiting because the XOFF character was transmitted. If this member is TRUE, transmission is waiting. Transmission halts when the XOFF character is transmitted to a system that takes the next character as XON, regardless of the actual character.
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fEof
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Specifies whether the end-of-file (EOF) character has been received. If this member is TRUE, the EOF character has been received.
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fTxim
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If this member is TRUE, there is a character queued for transmission that has come to the communications device by way of the TransmitCommChar function. The communications device transmits such a character ahead of other characters in the device's output buffer.
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fReserved
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Reserved; do not use.
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cbInQue
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Specifies the number of bytes received by the serial provider but not yet read by a ReadFile operation.
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cbOutQue
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Specifies the number of bytes of user data remaining to be transmitted for all write operations. This value will be zero for a nonoverlapped write.
QuickInfo
Windows NT: Requires version 3.1 or later.
Windows: Requires Windows 95 or later.
Windows CE: Requires version 1.0 or later.
Header: Declared in winbase.h.
See Also
Communications Overview, Communication Structures, ClearCommError, ReadFile, TransmitCommChar