As a specialist in Motion Centric Automation, Lenze has concentrated in the past on drive-related safety functions. In so-called drive-based safety, the safety functions are integrated directly into the drive. "The individual drive controllers, from which the dangerous movement originates in case of doubt, are thus made very effectively safe, because the integration into the drive ensures a short response time and makes external devices for monitoring the drive superfluous," says Michael Niehaus.

The Hamelin-based company is now extending its safety focus to the entire automation system. The basis for this is the new c250-S controller, which Lenze is presenting for the first time in Nuremberg and which is intended to pave the way for planning the complete drive, control and safety technology from a single source. Specifically, the c250-S is based on redundant hardware that meets the highest performance level PLe in accordance with DIN EN 13849-1 and communicates with the other components of the system via the FSoE protocol (Fail Safe over Ethercat). This safe extension of the Ethercat protocol is used by Lenze as a system bus due to the short response times and the possibility of precise time synchronization of all bus participants.

Programming is carried out in accordance with IEC 61131-3 on the basis of Codesys Safety using the standard function blocks defined by PLCopen. According to Michael Niehaus, the particular advantage of Lenze's new safety approach can be seen in engineering: "In future, the entire machine can be programmed with just one tool - regardless of whether it is 'gray' or 'yellow' control technology. In other words, the user can access both the safety-relevant and all other data of the overall system without system interruption. Interface problems and time-consuming familiarization times with tools from different manufacturers are now a thing of the past." Using prepared application solutions from Lenze's 'Application Software Toolbox', a corresponding module can, for example, control the reduction of the speed of a machine in manual mode, while the safety within the system monitors the safe maximum speed of the axes and thus prevents any danger to the operator.

As far as the safe I/O level is concerned, a combined I/O module (4 inputs, 2 outputs) is available as a first step. Expansion with additional modules is planned. Both contact sensors and light barriers or laser scanners with safe semiconductor outputs can be connected. The latter are a special feature, as they can switch up to 2 A. "By integrating the I/O modules directly into the safety controller, safety can be encapsulated in a modular machine concept, making it easy to standardize and reuse," says Niehaus.

As already mentioned, the drive-related safety functions are activated via FSoE. The safe position and drive values generated in the inverter can also be accessed as 16- or 32-bit values. "This opens up new possibilities for implementing safe machine functions, for example when movements of machine parts need to be safeguarded in such a way that operators can interact with the machine in the tightest of spaces," explains the Functional Safety Technology Manager. The new safety controller will be available for projects from December 2016.