This structure is used in the SetCommTimeouts and GetCommTimeouts functions to set and query the time-out parameters for a communication device. The parameters determine the behavior of the ReadFile and WriteFile function operations on the device.
At a Glance
| Header file: | Winbase.h |
| Windows CE versions: | 1.0 and later |
Syntax
typedef struct _COMMTIMEOUTS {
DWORD ReadIntervalTimeout;
DWORD ReadTotalTimeoutMultiplier;
DWORD ReadTotalTimeoutConstant;
DWORD WriteTotalTimeoutMultiplier;
DWORD WriteTotalTimeoutConstant;
} COMMTIMEOUTS,*LPCOMMTIMEOUTS;
Members
ReadIntervalTimeout
Specifies the maximum acceptable time, in milliseconds, to elapse between the arrival of two characters on the communication line. During a ReadFile operation, the time period begins when the first character is received. If the interval between the arrival of any two characters exceeds this amount, the ReadFile operation is completed and any buffered data is returned. A value of zero indicates that interval time-outs are not used.
ReadTotalTimeoutMultiplier
Specifies the multiplier, in milliseconds, used to calculate the total time-out period for read operations. For each read operation, this value is multiplied by the requested number of bytes to be read.
ReadTotalTimeoutConstant
Specifies the constant, in milliseconds, used to calculate the total time-out period for read operations. For each read operation, this value is added to the product of the ReadTotalTimeoutMultiplier member and the requested number of bytes.
A value of zero for both the ReadTotalTimeoutMultiplier and ReadTotalTimeoutConstant members indicates that total time-outs are not used for read operations.
WriteTotalTimeoutMultiplier
Specifies the multiplier, in milliseconds, used to calculate the total time-out period for write operations. For each write operation, this value is multiplied by the number of bytes to be written.
WriteTotalTimeoutConstant
Specifies the constant, in milliseconds, used to calculate the total time-out period for write operations. For each write operation, this value is added to the product of the WriteTotalTimeoutMultiplier member and the number of bytes to be written.
A value of zero for both the WriteTotalTimeoutMultiplier and WriteTotalTimeoutConstant members indicates that total time-outs are not used for write operations.
Remarks
If an application sets ReadIntervalTimeout and ReadTotalTimeoutMultiplier to MAXDWORD and sets ReadTotalTimeoutConstant to a value greater than zero and less than MAXDWORD, one of the following occurs when the ReadFile function is called:
See Also