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wclSerial::wclSerialTimeouts Structure

Contains the time-out parameters for a communications device.

Syntax
C++
typedef struct {
  unsigned long ReadInterval;
  unsigned long ReadMultiplier;
  unsigned long ReadConstant;
  unsigned long WriteMultiplier;
  unsigned long WriteConstant;
} wclSerialTimeouts;
Members 
Description 
unsigned long ReadInterval; 
The maximum time allowed to elapse before the arrival of the next byte on the communications line, in milliseconds. If the interval between the arrival of any two bytes 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.
A value of MAXDWORD, combined with zero values for both the ReadConstant and ReadMultiplier members, specifies that the read operation is to return immediately with the bytes that have already been received, even if no bytes have been received.
 
unsigned long ReadMultiplier; 
The multiplier used to calculate the total time-out period for read operations, in milliseconds. For each read operation, this value is multiplied by the requested number of bytes to be read.  
unsigned long ReadConstant; 
A constant used to calculate the total time-out period for read operations, in milliseconds. For each read operation, this value is added to the product of the ReadMultiplier member and the requested number of bytes.
A value of zero for both the ReadMultiplier and ReadConstant members indicates that total time-outs are not used for read operations.
 
unsigned long WriteMultiplier; 
The multiplier used to calculate the total time-out period for write operations, in milliseconds. For each write operation, this value is multiplied by the number of bytes to be written.  
unsigned long WriteConstant; 
A constant used to calculate the total time-out period for write operations, in milliseconds. For each write operation, this value is added to the product of the WriteMultiplier member and the number of bytes to be written.
A value of zero for both the WriteMultiplier and WriteConstant members indicates that total time-outs are not used for write operations.
 

If an application sets ReadInterval and ReadMultiplier to MAXDWORD and sets ReadConstant to a value greater than zero and less than MAXDWORD, one of the following occurs when the ReadFile function is called:  

If there are any bytes in the input buffer, ReadFile returns immediately with the bytes in the buffer.  

If there are no bytes in the input buffer, ReadFile waits until a byte arrives and then returns immediately.  

If no bytes arrive within the time specified by ReadConstant, ReadFile times out.  

 

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