Chapter 5 RS-232 Library
© National Instruments Corporation 5-11 LabWindows/CVI Standard Libraries
ComRd
int nbytes = ComRd (int COMPort, char buffer[], int count);
Purpose
Reads count bytes from input queue of the specified port and stores them in buffer. Returns
either on time-out or when count bytes have been read. Returns an integer value indicating the
number of bytes read from queue.
Parameters
Input COMPort integer Range 1 through 16.
count integer 0 value takes no bytes from
queue.
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 in the specified time-out period. This
may occur when no data has been received within the time-out period.
The function returns an error code if the port is not open or parameter values are invalid.
Example
/* Read 100 bytes from input queue of COM1 into buf. */
int n;
char buf[100];
:
n = ComRd (1, buf, 100);
if (n != 100)
/* Time-out or error occurred before read completed. */ ;