hi guys… we r using the pneumatics for the first time and we are facing some technical problems… we can’t figure out that How we attech the single switch solenoid to the circuit…coz we can not find any point on the solenoid where we can attach the wire…so if u guys can help us figuring it out…thanks:confused: 
If you are talking about the SMC valve then black is for ground and red would go to a spike relay. You could connect both to the relay if you have no need to use the other output on the relay.
If you are talking about the Festo valve, you need to wire it yourself. The connector is included in the box. 1- Negative(ground) 2- Positive (spike) 3- not used.