We have a problem with our pneumatics. When we put air into the system the cylinders are stuck on and the only way we can shut them off is to get stop the air from going into them. Right now we are looking at the wiring and tubing to see if there is a problem but what else could it be?
With the valves commonly used in First air will always be ported to one side of the cylinder or the other. With the Festo two solenoid valve this will be the side last activated. You can manually actuate the solenoid to make extend/retract. This is legal & common. If your solenoid is energized when the robot is disabled, you have a wiring problem.