INTEGRATING ELECTRIC AND PNEUMATIC CONTROLS

ELECTRICS & PNEUMATICS RARELY WORKED WELL TOGETHER

This concept has had a long gestation period. It wasn’t so many years ago that even the very structure of engineering functions within companies conspired to ensure that the disparate worlds of pneumatics and electrics would never meet. At the machine level, this meant that the technologies rarely worked well together – and even when they did, the cost of closing the gap was extremely high in terms of labour. In fact, it was often the case that the two disciplines only came together for the first time at the final system commissioning stages, which is hardly the best time to be resolving critical system integration issues. A typical sorting machine with a series of pick-and-place stations – comprising X-Y electrical axes, pneumatically-operated stop gates and vacuum pick-up devices – provides a very good example of these issues. Such a machine would traditionally be configured with a central PC/PLC, and demand significant time overheads for sub-system integration, wiring and commissioning. During final build, what starts off as a simple task can rapidly become more complicated, as the various feedback systems are incorporated.

SAFETY REQUIRES A MULTI-DISCIPLINED APPROACH

Machine safety issues also require a multi-disciplined approach.

WHAT TO LOOK FOR IN AN INTEGRATED AUTOMATION PLATFORM

So, given that we are now on the threshold of having control engineers who are happy to embrace electrical and pneumatic systems, where are the multitechnology products they need to make their life easier? Well, they do exist, but it is important to note that not all such products are, or are ever likely to be, equal.

FESTO CPX – NOW WITH CODESYS CONTROLLER

Festo’s CPX multifunctional valve terminal probably comes closest to the ideal – it is still the only product on the market with a backplane bus that spans both pneumatic and electrical functions, some 8 years after it was launched. And since that time, Festo has significantly extended the CPX’s range of pneumatic and electrical technology modules, which now includes a fully synchronous 8-axis controller for electric drives and an asynchronous multi-axis fieldbus gateway. The latest addition is a CoDeSys embedded controller – essentially an industry-standard PLC with additional functionality – which provides a technically elegant means of controlling all the units in a CPX terminal, regardless of whether they are for pneumatic or electric drives, or for I/O functions. Suitable for single and multi-axis applications, the controller can operate autonomously or in conjunction with a host controller such as a master PLC, and can also be used as an intelligent slave in fieldbusbased systems, to provide localised signal pre-processing.