The results of these tests can be sent to a central control system, which is able to generate and display appropriate clear text messages. This means the diagnostics system does not have to wait for a fault to occur before it begins to function. The system can carry out its check as soon as the machine is switched on, to determine whether the pneumatic subsystem is operable and functioning correctly in all areas. DDL units can mount on any valve manifold with a 25-pin D-Sub connector, and are equipped with industrial M12 plug connectors for communication with a standalone DDL module or directly with the central PLC.