Maximum time allowed to elapse between the arrival of two characters on the communications line, in milliseconds.
During a Read method, the time period begins when the first character is received. If the interval between the arrival of any two characters exceeds this amount, the Read method is completed and any buffered data is returned. A value of zero indicates that interval time-outs are not used.
A value of -1, combined with zero values for both the TimeoutReadTotalConstant and TimeoutReadTotalMultiplier members, specifies that the read operation is to return immediately with the characters that have already been received, even if no characters have been received.