The fastest speed in RC is a 30KHz clock, instead of the standard ~10Hz. It doesn't have to mean that you can't use the US sensor, it just means you can't use it with a high speed clock. So if you have your US connected to S1 then just don't use the fast speed on that port. You could still use the faster speeds on the other ports. The faster speeds are nice but you don't need them nearly as much as you might think
| My Blog: I'd Rather Be Building Robots (http://botbench.com)
| RobotC 3rd Party Driver Suite: (http://rdpartyrobotcdr.sourceforge.net)
| Some people, when confronted with a problem, think, "I know, I'll use threads,"
| and then two they hav erpoblesms. (@nedbat)