Rig shows benefits of electropneumatic networks

Kuhnke UK has created a training rig where engineers can familiarise themselves with a compact alternative to bulky pneumatic valves, developed specifically to work with the ASi fieldbus.

Kuhnke UK has created an extensive training rig where manufacturing engineers can familiarise themselves with a compact alternative to bulky pneumatic valves, developed specifically to work with the ASi fieldbus.

Airbox technology allows the customer to eliminate all valve islands and instead create a modular network of compact electropneumatic boxes, each containing between two and four I/Os.

Such I/Os can be configured to be mono- or bistable in nature.

"Our training rig will allow those in industry to contrast the operation of a fieldbus-networked, pneumatic manufacturing cell based around Airbox, with one reliant on traditional valves", explains Kuhnke UK's Managing Director, Brod Bass.

"In particular, they will be able to see how Airbox works hand-in-glove with ASi; whilst reducing the working envelope, cable clutter and future costs if modification or expansion become desirable".

Developed by Kuhnke and marketed in association with Siemens, Airbox resides directly on the ASi (actuator-sensor interface) communications loop.

This fact, along with Airboxes' ultracompact footprint, allows the customer to align the electropneumatic I/O network immediately adjacent to the physical actuating layer in the control pyramid.

In this way, they can enjoy the full benefit of streamlined communications offered by the ASi fieldbus.

"It cannot be emphasised enough that Airbox is the only product designed specifically for ASi", stresses Bass.

"This fieldbus was specifically created to facilitate a flexible I/O network, residing at the interface between the intelligent and operational layers".

Airbox modules hook directly onto the yellow ASi communications ribbon.

Power can also be fed through this yellow cable, or - if control circumstances dictate - a two cable setup may be employed.

In the latter scenario, control information passes through the yellow cable, while power is routed through a similar black cable.

Either way, if the user needs to subsequently modify or extend their I/O profile; they can "plug and play" the Airbox modules without any need to reconfigure control algorithms.

Upgrading a fieldbus-networked group of valve islands is problematic, in that that each valve function, be it 3/2, 5/2 or another configuration, needs to be specified during setup.

"You have immediately lost the 'plug and play' simplicity offered by Airbox when opting for a conventional valve island system on ASi", suggests Bass.

Although there is complete technical fit between ASi and Airbox, valves islands must be configured to link into the fieldbus ribbon, by means of dedicated adapter cables.

This incurs two penalties.

First, it re-introduces the cable clutter that fieldbus seeks to eliminate.

Secondly, and crucially, in terms of diagnostics you have a dead space of understanding between the valve island and where it links into ASi.

If there is a fault, it may not be possible to pinpoint the source, as would be the case if Airbox was employed.

Bass adds: "In mating valves with the ASi protocol, you create a cumbersome compromise".

"What we have are conventional centralised blocks linked to - rather than residing on - a communications loop designed for decentralised control".

"It's akin to driving a tractor on a six-lane highway".

"In addition, it's worth the customer considering the level of technical support a valve company is likely to be able to offer those requiring assistance in formulating their work cell".

"We at Kuhnke, with our unique electropneumatic technology, now have widespread experience of installing ASi-based systems in the food and drink, automotive manufacturing, automation and other sectors".

The alliance with Siemens provides Kuhnke customers with a host of associated control gear that may be incorporated into such an electropneumatic manufacturing cell.

In particular, the e-stop emergency button, compliant with EN418 and rated to IP66/67, can be clipped directly onto the ASi yellow cable.

Siemens was the first to offer this IP67 rating, making the e-stop suitable to ultra-high-cleanliness applications, such as the dairy industry.

"E-stop also opens up ASi-Airbox to Category 4 safety applications", says Bass, "with the button operated via the yellow ASi cable".

"Our training rig demonstrates how having all I/O points residing directly on the ASi fieldbus ensures the operator receives transparent information".

"The result is a reduction in the time and cost traditionally associated with the commissioning and maintenance of electropneumatic networks".

Development of the Airbox training rig is seen by Kuhnke as the logical next step in illustrating to pneumatics users the operational and performance outputs delivered by the technology.

Bass suggests: "The Airbox-ASi system allows users requiring a modest amount of I/O to take charge of a cost-effective system that can be easily enhanced as required".

"Although it is competing against an established technology in pneumatic valve islands, we estimate that 50% of all new pneumatic output points specified to reside on ASi are now being configured with Airbox technology".

"Engineers now understand there is no need to compromise, when they can have a seamless solution that is truly fit for purpose".

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