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COMMPROP info Overview Group

The COMMPROP structure is used by the GetCommProperties function to return information about a given communications driver.

typedef struct _COMMPROP { // cmmp 

    WORD  wPacketLength;       // packet size, in bytes 

    WORD  wPacketVersion;      // packet version 

    DWORD dwServiceMask;       // services implemented 

    DWORD dwReserved1;         // reserved 

    DWORD dwMaxTxQueue;        // max Tx bufsize, in bytes 

    DWORD dwMaxRxQueue;        // max Rx bufsize, in bytes 

    DWORD dwMaxBaud;           // max baud rate, in bps 

    DWORD dwProvSubType;       // specific provider type 

    DWORD dwProvCapabilities;  // capabilities supported 

    DWORD dwSettableParams;    // changable parameters 

    DWORD dwSettableBaud;      // allowable baud rates 

    WORD  wSettableData;       // allowable byte sizes 

    WORD  wSettableStopParity; // stop bits/parity allowed 

    DWORD dwCurrentTxQueue;    // Tx buffer size, in bytes 

    DWORD dwCurrentRxQueue;    // Rx buffer size, in bytes 

    DWORD dwProvSpec1;         // provider-specific data 

    DWORD dwProvSpec2;         // provider-specific data 

    WCHAR wcProvChar[1];       // provider-specific data 

} COMMPROP;

Members

wPacketLength

Specifies the size, in bytes, of the entire data packet, regardless of the amount of data requested.

wPacketVersion

Specifies the version of the structure.

dwServiceMask

Specifies a bitmask indicating which services are implemented by this provider. The SP_SERIALCOMM value is always specified for communications providers, including modem providers.

dwReserved1

Reserved; do not use.

dwMaxTxQueue

Specifies the maximum size, in bytes, of the driver’s internal output buffer. A value of zero indicates that no maximum value is imposed by the serial provider.

dwMaxRxQueue

Specifies the maximum size, in bytes, of the driver’s internal input buffer. A value of zero indicates that no maximum value is imposed by the serial provider.

dwMaxBaud

Specifies the maximum allowable baud rate, in bits per second (bps). This member can be one of the following values:

Value	Meaning
BAUD_075	75 bps
BAUD_110	110 bps
BAUD_134_5	134.5 bps
BAUD_150	150 bps
BAUD_300	300 bps
BAUD_600	600 bps
BAUD_1200	1200 bps
BAUD_1800	1800 bps
BAUD_2400	2400 bps
BAUD_4800	4800 bps
BAUD_7200	7200 bps
BAUD_9600	9600 bps
BAUD_14400	14400 bps
BAUD_19200	19200 bps
BAUD_38400	38400 bps
BAUD_56K	56K bps
BAUD_57600	57600 bps
BAUD_115200	115200 bps
BAUD_128K	128K bps
BAUD_USER	Programmable baud rates available

dwProvSubType

Specifies the specific communications provider type:

Value	Meaning
PST_FAX	FAX device
PST_LAT	LAT protocol
PST_MODEM	Modem device
PST_NETWORK_BRIDGE	Unspecified network bridge
PST_PARALLELPORT	Parallel port
PST_RS232	RS-232 serial port
PST_RS422	RS-422 port
PST_RS423	RS-423 port
PST_RS449	RS-449 port
PST_SCANNER	Scanner device
PST_TCPIP_TELNET	TCP/IP Telnet® protocol
PST_UNSPECIFIED	Unspecified
PST_X25	X.25 standards

dwProvCapabilities

Specifies a bitmask indicating the capabilities offered by the provider. This member can be one of the following values:

Value	Meaning
PCF_16BITMODE	Special 16-bit mode supported
PCF_DTRDSR	DTR (data-terminal-ready)/DSR (data-set-ready) supported
PCF_INTTIMEOUTS	Interval time-outs supported
PCF_PARITY_CHECK	Parity checking supported
PCF_RLSD	RLSD (receive-line-signal-detect) supported
PCF_RTSCTS	RTS (request-to-send)/CTS (clear-to-send) supported
PCF_SETXCHAR	Settable XON/XOFF supported
PCF_SPECIALCHARS	Special character support provided
PCF_TOTALTIMEOUTS	Total (elapsed) time-outs supported
PCF_XONXOFF	XON/XOFF flow control supported

dwSettableParams

Specifies a bitmask indicating the communications parameter that can be changed. This member can be one of the following values:

Value	Meaning
SP_BAUD	Baud rate
SP_DATABITS	Data bits
SP_HANDSHAKING	Handshaking (flow control)
SP_PARITY	Parity
SP_PARITY_CHECK	Parity checking
SP_RLSD	RLSD (receive-line-signal-detect)
SP_STOPBITS	Stop bits

dwSettableBaud

Specifies a bitmask indicating the baud rates that can be used. For values, see the dwMaxBaud member.

wSettableData

Specifies a bitmask indicating the number of data bits that can be set. This member can be one of the following values:

Value	Meaning
DATABITS_5	5 data bits
DATABITS_6	6 data bits
DATABITS_7	7 data bits
DATABITS_8	8 data bits
DATABITS_16	16 data bits
DATABITS_16X	Special wide path through serial hardware lines

wSettableStopParity

Specifies a bitmask indicating the stop bit and parity settings that can be selected. This member can be one of the following values:

Value	Meaning
STOPBITS_10	1 stop bit
STOPBITS_15	1.5 stop bits
STOPBITS_20	2 stop bits
PARITY_NONE	No parity
PARITY_ODD	Odd parity
PARITY_EVEN	Even parity
PARITY_MARK	Mark parity
PARITY_SPACE	Space parity

dwCurrentTxQueue

Specifies the size, in bytes, of the driver’s internal output buffer. A value of zero indicates that the value is unavailable.

dwCurrentRxQueue

Specifies the size, in bytes, of the driver’s internal input buffer. A value of zero indicates that the value is unavailable.

dwProvSpec1

Specifies provider-specific data. Applications should ignore this member unless they have detailed information about the format of the data required by the provider.

Set this member to COMMPROP_INITIALIZED before calling the GetCommProperties function to indicate that the wPacketLength member is already valid.

dwProvSpec2

Specifies provider-specific data. Applications should ignore this member unless they have detailed information about the format of the data required by the provider.

wcProvChar

Specifies provider-specific data. Applications should ignore this member unless they have detailed information about the format of the data required by the provider.

Remarks

The contents of the dwProvSpec1, dwProvSpec2, and wcProvChar members depend on the provider subtype (specified by the dwProvSubType member).

If the provider subtype is PST_MODEM, these members are used as follows:

Value

Meaning

dwProvSpec1

Not used.

dwProvSpec2

Not used.

wcProvChar

Contains a MODEMDEVCAPS structure.

COMMPROP info Overview Group

Members

Remarks

See Also