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1 Jan 1970

Safety and control are starting to converge

Visitors to the Pilz stand at the 2004 Hannover Industry Fair may have noticed a new logo on some of the displays, literature and multi-media presentations. 'Safety & Control' is the Pilz vision for how safety and conventional automation control should converge. For those who have not yet seen the logo, it consists of a circular yellow arrow that encompasses an ampersand overlaid with the words 'safety' and 'control'.

Some suppliers think that the way ahead is for safety and conventional control signals to be transmitted on common cabling, effectively adding a safe layer to a conventional industrial fieldbus network. To monitor the safety data, special 'safe PLCs' or safety monitoring modules are installed on the network alongside the conventional controller.

Despite the proposals described above, Pilz has established from customers that there is still a preference for using specialist safety equipment for safety-relevant functions.

Furthermore, analysis of safety technology trends shows that complexity is increasing at an astonishing rate, and there is an ever-increasing need for more and more detailed diagnostics data. For example, production lines may need to be sub-divided into zones so that disruption to production is minimised in the event of a safety-related event in one area, yet the safety functions for the entire line need to be monitored centrally. Comprehensive diagnostics increase plant availability.

Legislation is also tightening, so we are likely to see safety control systems gaining additional built-in functionality. For instance, scheduled testing of safety components could be enforced by the safety controller inhibiting the line from restarting unless the tests are performed and the results are satisfactory.

Because of these trends, it is rapidly becoming the case that only relatively simple machinery will be able to make use of traditional logic circuits assembled from electromechanical safety relays. Software-configurable modular safety controllers and 'safe PLCs' such as the Pilz Programmable Safety System (PSS) will become more commonplace in order to deliver the complex logic, functionality and diagnostics required.

The technological balance between automation control and safe control is therefore shifting: whereas traditional machinery might have had a sophisticated control system and a simple (but highly robust) safety control system, tomorrow's machinery will have automation control systems and safety control systems that have similar levels of complexity. It is not inconceivable that future control cabinets may have two controllers, one safe and one standard, both of which contain comparable levels of 'intelligence'.

However, because the safe controller has a redundant architecture, the cost of the safe controller will probably be similar to that of the standard controller. So where does this lead?

Customers have already indicated the most cost-effective route for many machine builders and system integrators is the convergence of safety and standard controllers. This is a growing trend, offering significant savings by reducing hardware costs. All control will be brought within one universal controller, effectively making everything on the machine 'safe'.

This approach might be seen by some people as radical, and it is. It will also not be suitable for every application, but nothing will ever be. Nonetheless, Pilz is devoting significant resources to developing hardware and software that will deliver what future automation projects will require in order to implement this philosophy.

One of the keys to the success of this will be the software used to configure and/or program the controllers. Graphical user interfaces and drag-and-drop tools are easier to learn and use than traditional programming techniques, thereby saving development and maintenance costs. Having developed drag-and-drop configuration software for the PNOZmulti software-configurable modular safety controller, Pilz will be using this as the foundation on which to build more sophisticated tools that can be used with programmable safety systems. Of course, there will still be a need for higher-level tools for creating specialist function blocks, but the general trend is towards graphical methods.

Moreover, software is increasingly becoming the major differentiator between products from different suppliers. Greater capability can be incorporated within hardware relatively easily today, but the user interface at the front-end can make one company's products stand head-and-shoulders above those from other companies. As a result, Pilz is now investing more in software development than ever before, as well as gathering feedback from users and talking to customers about their future requirements.

Pilz has always been a market leader, with developments such as: the first safety relay; the first programmable safety system; the first safe, open fieldbus system, SafetyBUS p; the first solid-state safety 'relay'; and the first software-configurable modular safety controller. 2004 sees the unveiling of a new logo for 'Safety & Control', which is a small visible sign of a massive development programme and a new philosophy for the control of safety and standard functions. By adopting this approach, machine builders, system integrators and end users will benefit from lower costs, reduced development time, improved integration of safety and standard control, and higher machine availability due to the standard control being handled by higher-integrity hardware and software. You can expect to see much more of the 'Safety & Control' logo in the future, and some innovative software and hardware products will be launched to enable this concept to be put into practice.


Pilz Automation Ltd
Pilz House, Little Colliers Field
Corby, Northants, NN18 8TJ
United Kingdom

Telephone: +44 1536 460766
E-Mail: sales@pilz.co.uk

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Telephone: +44 1536 460766
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