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.