Safety Controller with Flexi Loop

The Flexi Soft Safety Controller which supports communications to PLCs via all standard field bus communications protocols now includes a new feature called Flexi Loop. This adds the capability to series up to 32 sensors and maintain the highest level of safety with complete diagnostic capabilities.

Aw 25450 Safety Controller Node

With the ability to cascade up to 32 safety switches and OSSD (output signal switching device) safety sensors onto one loop, regardless of who manufacturers those devices, the Flexi Loop safety controller node from SICK can significantly reduce the time and cost associated with wiring a safety network. In addition, the Flexi Loop safety controller also supports diagnostics.

Any combination of safety switches and safety sensors with OSSD outputs can be used with the Flexi Loop. Sensors are powered with voltage directly via Flexi Loop using M12 standard connectors. This set-up also guarantees continuous diagnosis of all door switches, emergency stop push-buttons and sensors. Used in connection with Flexi Soft safety modules the entire safety application can be tailored to meet the safety needs of any machine application.

The Flexi Loop, which is part of SICK’s safety controller family, uses a single cable with an M12 plug to connect e-stops, sensors, switches, lamps, pushbuttons and interlocks. Maximum length between nodes can reach up to 30 meters. Flexi Soft safety controllers can support up to eight Flexi Loops, enabling a total of 256 switches in a small footprint. Having this capability means the Flexi Loop requires minimal wiring effort, which saves costs and ensures fast configuration.

Flexi Loop supports all common fieldbuses, including EtherNet/IP, CANopen, DeviceNet and PROFINET IO.

Regardless of the number of sensors or switches, Flexi Loop is able to maintain a performance level of PLe since it monitors each sensor individually. The Flexi Loop is ideal for safety applications in the packaging, commercial goods, electronics, and solar industries that require several doors, e-stops and electro-sensitive protective devices.

At- a-Glance

Principal features of the Flexi Loop include:

  •  Ability to cascade 32 sensors with up to 30 meters per segment in compliance with performance level PLe;
  •  Compatible with all sensors from other manufacturers;
  •  Transfer of detailed diagnostic information;
  •  Integrated standard inputs and outputs;
  •  Power supply for sensors is included;
  •  Connection of the sensors via standard cable with M12 plug; and
  •  IP 67 enclosure rating protects against dust and water.


  •  Cascading of safety switches and safety sensors with OSSD outputs minimizes the wiring effort and the inputs of the safety controller, which saves costs;
  •  Easy retrofitting of existing machines;
  •  Simple calculation of the performance level saves time since the Flexi Loop node monitors each sensor individually;
  •  User-friendly due to quick and easy configuration;
  •  Ability to be used over long distances increases application flexibility;
  •  Detailed diagnostic information minimizes system downtime; and
  •  Seamless system integration and communication with other SICK safety controllers


  •  Machines with a high number of doors, emergency stop pushbuttons, tactile and electro-sensitive protective devices;
  •  Systems with a large footprint and decentralized safety paths;
  •  Packaging and electronics industries;
  •  Storage and conveyor systems

The video below explains how Flexi Loop can be used to safeguard large machine applications.

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