Look on the page with all the manuals
http://usfirst.org/roboticsprograms/...nt.aspx?id=452
look at Section 8, look for
Sensor Manual_RevA
Also see that the Sensor Manual refers to the datasheet here:
http://usfirst.org/roboticsprograms/....aspx?id=16337
it should tell you everything you need to know. If not, please ask us for more help.