It's just a pneumatic solenoid valve stack. Depending on how large your cylinders are and how much air they take, there are different sizes of valve.
There are also different types of "spools" in the valves depending on what type of actuation you want and what type of cylinder you have (single- or double-acting). Do you want "on" to extend the cylinder and "off" to retract it? Do you want the cylinder to remain in its position if you lose power, or do you want it to retract? Etc., etc...
Take a look here:A serial interface is a little trickier if you want to control it with a PC. Most serial valve control is based on industrial protocols like DeviceNet, Profibus, DH-485, etc. Another possibility is to drive the valves discretely with processor outputs through power transistors, or solid-state relays, like with a PIC chip or a Basic Stamp.
Don Kansas City