hi, I recently purchased a HS-422 services motor from robot shop and it is not quite functioning the way I expected it to. The first question/concern I have about it is that it is only rotating 180 degrees for me. This would be fine except the spec says it only rotates clockwise. If the polarities were to be switched, would it rotate ccw and or would this damage the servo?
A servo does not operate like a normal DC motor - you cannot and should not reverse the polarity of the wires; it is the RC signal which determines the position. You are correct that the 422 (as with most standard RC servo motors) only rotates -90 to +90 degrees.
How do you get it to turn ccw then or can you get it to turn ccw?
You specify a position. It cannot rotate more than 180 degrees, so if its current position is centered (1500us pulse) and you specify 600us, it will rotate counterclockwise to go to that new position. It all comes down to the current angle versus the desired / new angle.