Yes the above post is correct, however this valve alone isn't enough to stop a cylinder stroke midway. You should use another double solenoid valve so that one valve controls the air into the cylinder and the other valve controls the exhaust. You see you need to lock the air in the exhaust side to stop the cylinder mid stroke. Check out this post:
http://www.chiefdelphi.com/forums/sh...ght=pneumatics
Post #11 has a simple diagram that shows you how to do it.
Good luck!