I am using the VISA Read vi to read a string from the serial port.  I have a property node that checks the number of bytes at the port and that is wired directly to the "byte count" terminal of the VISA Read vi.  This generates a warning that says VISA Read reads only the number of bytes at the port.  No other problems are evident and this is what I want it to do anyway.  Should I do something else for the byte count input?