LoopBack - Set this to 1 if internal loop-back is to be performed (make sure this is deleted after running the test). When set to 0, a loop-back connector which ties pins 2 and 3 together is necessary at each port.
Note: The COMx driver does not support internal loop-back. The external loop-back is the default mode.
Size - Sets the maximum frame size. The length of each frame transmitted is random between 1 to 'Size'-1. The default size is 512.
Note: The total number of errors should be 0. If the number of errors reported is not zero, your serial hardware is not operating properly.