| UID | title | description | helpviewer_keywords | old-location | tech.root | ms.assetid | ms.date | ms.keywords | req.header | req.include-header | req.target-type | req.target-min-winverclnt | req.target-min-winversvr | req.kmdf-ver | req.umdf-ver | req.ddi-compliance | req.unicode-ansi | req.idl | req.max-support | req.namespace | req.assembly | req.type-library | req.lib | req.dll | req.irql | targetos | req.typenames | req.redist | ms.custom | f1_keywords | dev_langs | topic_type | api_type | api_location | api_name | |||||||||||||||||||||||||||||||||||||||||||||||||||
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NS:winbase._DCB |
DCB (winbase.h) |
Defines the control setting for a serial communications device. |
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base\dcb_str.htm |
base |
9dccd2c6-44b7-4609-a2b9-9815430bf3c7 |
12/05/2018 |
*LPDCB, CBR_110, CBR_115200, CBR_1200, CBR_128000, CBR_14400, CBR_19200, CBR_2400, CBR_256000, CBR_300, CBR_38400, CBR_4800, CBR_57600, CBR_600, CBR_9600, DCB, DCB structure, DTR_CONTROL_DISABLE, DTR_CONTROL_ENABLE, DTR_CONTROL_HANDSHAKE, EVENPARITY, LPDCB, LPDCB structure pointer, MARKPARITY, NOPARITY, ODDPARITY, ONE5STOPBITS, ONESTOPBIT, RTS_CONTROL_DISABLE, RTS_CONTROL_ENABLE, RTS_CONTROL_HANDSHAKE, RTS_CONTROL_TOGGLE, SPACEPARITY, TWOSTOPBITS, _DCB, _win32_dcb_str, base.dcb_str, winbase/DCB, winbase/LPDCB |
winbase.h |
Windows.h |
Windows |
Windows XP |
Windows Server 2003 |
Windows |
DCB, *LPDCB |
19H1 |
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Defines the control setting for a serial communications device.
The length of the structure, in bytes. The caller must set this member to
sizeof(DCB).
The baud rate at which the communications device operates. This member can be an actual baud rate value, or one of the following indexes.
If this member is TRUE, binary mode is enabled. Windows does not support nonbinary mode transfers, so this member must be TRUE.
If this member is TRUE, parity checking is performed and errors are reported.
If this member is TRUE, 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.
If this member is TRUE, 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.
The DTR (data-terminal-ready) flow control. This member can be one of the following values.
| Value | Meaning |
|---|---|
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Disables the DTR line when the device is opened and leaves it disabled. |
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Enables the DTR line when the device is opened and leaves it on. |
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Enables DTR handshaking. If handshaking is enabled, it is an error for the application to adjust the line by using the EscapeCommFunction function. |
If this member is TRUE, the communications driver is sensitive to the state of the DSR signal. The driver ignores any bytes received, unless the DSR modem input line is high.
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.
Indicates 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.
Indicates 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.
Indicates whether bytes received with parity errors are replaced with the character specified by the ErrorChar member. If this member is TRUE and the fParity member is TRUE, replacement occurs.
If this member is TRUE, null bytes are discarded when received.
The RTS (request-to-send) flow control. This member can be one of the following values.
| Value | Meaning |
|---|---|
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Disables the RTS line when the device is opened and leaves it disabled. |
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Enables the RTS line when the device is opened and leaves it on. |
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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 EscapeCommFunction function. |
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Specifies that the RTS line will be high if bytes are available for transmission. After all buffered bytes have been sent, the RTS line will be low. |
If this member is TRUE, the driver terminates all read and write operations with an error status if an error occurs. The driver will not accept any further communications operations until the application has acknowledged the error by calling the ClearCommError function.
Reserved; do not use.
Reserved; must be zero.
The minimum number of bytes in use allowed in the input buffer before flow control is activated to allow transmission by the sender. This assumes that either XON/XOFF, RTS, or DTR input flow control is specified in the fInX, fRtsControl, or fDtrControl members.
The minimum number of free bytes allowed in the input buffer before flow control is activated to inhibit the sender. Note that the sender may transmit characters after the flow control signal has been activated, so this value should never be zero. This assumes that either XON/XOFF, RTS, or DTR input flow control is specified in the fInX, fRtsControl, or fDtrControl members. The maximum number of bytes in use allowed is calculated by subtracting this value from the size, in bytes, of the input buffer.
The number of bits in the bytes transmitted and received.
The parity scheme to be used. This member can be one of the following values.
| Value | Meaning |
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Even parity. |
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Mark parity. |
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No parity. |
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Odd parity. |
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Space parity. |
The number of stop bits to be used. This member can be one of the following values.
| Value | Meaning |
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1 stop bit. |
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1.5 stop bits. |
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2 stop bits. |
The value of the XON character for both transmission and reception.
The value of the XOFF character for both transmission and reception.
The value of the character used to replace bytes received with a parity error.
The value of the character used to signal the end of data.
The value of the character used to signal an event.
Reserved; do not use.
When a DCB structure is used to configure the 8250, the following restrictions apply to the values specified for the ByteSize and StopBits members:
- The number of data bits must be 5 to 8 bits.
- The use of 5 data bits with 2 stop bits is an invalid combination, as is 6, 7, or 8 data bits with 1.5 stop bits.