This makes it particularly interesting, from both a technical and economic standpoint, for machines and production plants with a large number of doors, protective switches, guards, and emergency stop buttons, as well as guards protected by electrosensitive devices on the machines. Its cascade connection via Flexi Loop is exceptionally economical because the entire loop only requires one safe switching input, and standard unshielded 5-wire cables with an M12 connector can be used.
Connection nodes are available for electromechanical safety switches and safety sensors with output signal switching devices (OSSDs) for serial connection and integration into the various Flexi Soft safety controller expansion modules. The Flexi Loop node contains the safe disconnect signal for the entire cascade, as well as diagnostic data for each element integrated into the Loop. Connected sensors receive 24 V power via the Flexi Loop. Each node has a standard (non-safe) input and a standard (non-safe) output that supports function switches, door interlocks, or an indicator light. The distance between nodes can be up to 30 m, meaning a fully configured loop can reach a length of 960 m. The diagnostic data transmitted by each switch or sensor includes disconnection information ("Who triggered the switch?") and, in the event of a fault, the cause of the error ("Why did the switch occur?"). This simplifies machine diagnosis. The end result is that repair and maintenance work can be carried out quickly and efficiently, reducing machine downtime and the associated costs.
One of Flexi Loop's major innovations is making cascade connections safer. With conventional connections, certain errors cannot be detected because they are masked by the series connection. Flexi Loop prevents this by monitoring each individual sensor. From a safety perspective, conventionally connecting multiple sensors results in a lower safety level, down to PL do or PL c. In contrast, cascading switches and sensors with Flexi Loop consistently meets the PL e requirements according to DIN EN ISO 13849-1, provided the appropriate devices are used.
Flexi Loop is compatible with safety switches and sensors from any brand, thus preserving the machine manufacturer's independence when making purchases, as well as that of the end customer. The simplest solution, however, is to use SICK switches with plug-and-play technology: thanks to their M12 connectors and appropriate pin assignment, they come ready to work with Flexi Loop.
