Slade,
The Serial Port Read VI input for 'requested byte count' specifies the number of bytes to read at the port - you could enter 201 here, however, to read all the bytes at the port (no matter how many), you must first use the Bytes at Serial Port' VI which reads the byte count queued at the port and forwards that on to you Read VI.
This should work for what your doing, good luck with it, Doug