From HW's Buildings Forum:
255 is a valid output from the Compare block. If the Spyder boots up and the input to the Compare is within the hysteresis band then the output will be 255. Once the input falls outside of that band then the output will be 0 or 1. You'll need to link the output of the Compare to a Select block if the arrangement of your logic requires you to filter out the 255. Put a 0 or 1 in the Select's Default slot to define what action to take on an input of 255.