Configurable Safety Relays Increase Flexibility

Similar to progress in the automation technology sector, safety technology has gradually developed from hard-wired relay technology to contact-based safety relays and devices with integrated logic function and beyond to flexible, configurable safety relays. The idea was to make safety technology more transparent and manageable for the user. This was the major driving force behind development of the devices and ultimately led also to the development of new types of configuration tools, which graphically display function and logic and then forward the configured setting to the relay via memory chip. The result is a high degree of flexibility for the responsible electrical design engineer; their plans only have to consider the number of digital and analogue inputs/outputs required. They can incorporate the functions at some later date and adapt them to suit the changed situation if necessary. At the same time, any work involved in wiring the logic functions also disappears.

With this generation of devices, the safety functions and their logic connections are configured exclusively via the software tool. The manufacturer provides the safety functions within application blocks; certified bodies such as BG or TÜV will have already tested them for safety. With the help of safe application blocks and the logic connections between these blocks, the plant or machine builder creates the safety-related application they require, an application which they would previously have implemented by wiring contactors and relays in a laborious, time-consuming process. Contacts and wires are replaced by lines between the ready-made
application blocks. An electrical circuit diagram showing the logic functions is no longer required.

Logic connections between the blocks for simple configuration.

Not only is it easy to connect the application blocks to each other, a simple click of the mouse is all it takes to adapt them fully to the requirements of the relevant application. Block properties define the behavior of the individual blocks within the application: whether single or multi-channel, with or without automatic reset, e.g. when a safety gate is closed. Parameters that determine how a block will behave can be easily set in accordance with the application's safety requirement.

Configure function elements.

The parameters available in the “Configure Function Element” window (see illustration) essentially mirror the familiar functions from the safety relays. They no longer have to be set laboriously on the device or be selected via jumpers; with the parameter tool everything operates in the simplest way possible. Users will find all the useful, proven elements from the world of the classic safety relays, just represented in a different format. This new configuration method has another quite simple, safety-related benefit: Once the configuration has been selected, it cannot easily be modified by unauthorized persons via screwdriver or device selector switch.

Simple configuration of the required input and output modules, plus the availability of special modules for speed or analog processing, enable the user to create a safety system that suits his own individual needs. Functions can be added or adapted later with relative ease. The user simply selects these modules from a hardware list and then creates the necessary logic functions.

the New Directive?

New Profinet Interface Proves Impressive

Pilz decentralized I/O system, PSSuniversal, used in the automotive industry Pilz is to be the exclusive supplier of decentralized I/O periphery with protection type IP20 to automotive manufacturer BMW, effective immediately. In the future, the automotive group will use the PSSuniversal decentralized I/O system worldwide.

A prerequisite was the development of a new head module with Profinet interface, which was achieved in close cooperation with BMW. This was an impressive control solution from both a technical and an economic point of view. Thanks to the customized, certified Profinet interface, the decentralized I/O system PSSuniversal can be integrated seamlessly and safely into existing or new plant structures. “We regard the openness of control solutions not just in terms of investment protection. We are really keen to give users the chance to choose the solution that best suits their project”, says Albrecht Feucht, from Key Account Automotive at Pilz.

Open systems stimulate competition Under the scope of AIDA (Automotive Initiative of German Domestic Automobile Manufacturers), German automotive manufacturers have opted to use Profinet as a standardized communication medium, but AIDA has also stated that competition needs to be guaranteed where the connected control solution is concerned.

The decision in favor of Pilz was preceded by a comprehensive evaluation of the market and all available products by experts from BMW. In addition to its openness toward Profinet, other criteria included the system’s cost effectiveness plus the ability to link standard control functions and safety functions. Intense cooperation and continual coordination with BMW during the two-year development period paved the way for the launch of a user friendly system which meets the exact requirements. System is easy to handle. The integrated safety principle of the PSSuniversal represents a key distinguishing feature in comparison with existing solutions.

On the control system, the head module alone represents the safety-related subscribers, so that users only need to make the necessary settings at this central point. There is no need to assign awkward sub-addresses. Consequently all safety-related addresses on the Profinet Master can be put to optimal use.

Not only does this reduce the administrative work in assigning safe address ranges, it also
reduces costs, as less hardware is needed because the safety technology is concentrated
exclusively in the head module.

Initial projects with the decentralized I/O system Pilz PSSuniversal with Profinet connection will be implemented in BMW’s plants in Regensburg, Munich and Leipzig, with global applications to follow.