National Instruments 320682C

Chapter 5 RS-232 Library

Parameters

Input COMPort integer Range 1 through 32.

count integer If 0, no bytes are removed from

queue.

terminationByte integer Low byte contains the numeric

equivalent of the terminating

character.

Output buffer string The buffer in which to store the

data.

Return Value

nbytes integer Number of bytes read from the

input queue.

Using This Function

This function times out if the input queue remains empty within the specified time-out period.

This may occur when no data has been received during the time-out period. If the read

terminates on the termination byte, the byte is neither written to the buffer nor included in the

count.

If the termination character is either a carriage return (CR or decimal 13) or a linefeed (LF or

decimal 10), the function handles it as follows:

• If terminationByte = CR, and if the character immediately following CR is LF, discard the

LF in addition to the CR.

• If terminationByte = LF, and if the character immediately following LF is CR, discard the

CR in addition to the LF.

Only the bytes placed in buffer are included in the return count. If CR or LF is discarded

because it follows an LF or CR, it is not counted toward satisfying the count.

The function returns an error if the port is not open or parameter values are invalid.