The I/O Unit (on the top of the picture) has 2 16-input modules (connected to infrared sensors, cylinder position sensors), and 3 8-output modules (connected to the cylinder pneumatic valves).

The PCL (below the I/O unit) inputs and outputs are connected to the Swivel Arms.

On the lower section of the picture it is also visible the Power supply unit (left side) and the pneumatic electro valves (right side).