Safe series connection
Flexi Loop

The flexible and safe series connection with diagnostic function

Your Benefits

  • Reduce costs by reducing the number of inputs required on the safety controller and simplifying the wiring
  • Use Flexi Loop on modular machines and over long distances
  • Easily retrofit existing machinery
  • Quickly calculate the performance level
  • Configure the device nodes intuitively
  • Perform troubleshooting quickly thanks to detailed status information
  • Integrate Flexi Loop seamlessly into safety controllers from SICK


The flexible and safe series connection with diagnostic function

The Flexi Loop safe series connection allows you to connect up to 32 safety sensors up to PL e: With the Flexi Loop components, connecting safety locking devices, pushbuttons and lights to the safety controller is very simple. All sensors are directly supplied with voltage and connected via M12 standard cables. Sensors with OSSD outputs can be combined regardless of the manufacturer. The safety relays and Flexi Classic are either connected directly or via the master node. Easily configure Flexi Loop on a programmable safety controller using software. Flexi Loop offers consistent diagnostics both in the software and on the device itself.

At a glance
  • Safe series connection of up to 32 sensors regardless of the manufacturer
  • Up to 100 m in cable length between the sensors
  • IP65 and IP67 enclosure rating
  • Integration via M12 standard cable
  • Individual monitoring of the sensors up to PL e
  • Detailed diagnostic information
  • Direct voltage supply


Safe in series thanks to sophisticated device concept

The Flexi Loop safe series connection can wire up to 32 sensors together. The total wiring length can be up to 3,000 m with the right Flexi Loop nodes. Simply choose between 4 evaluation nodes and connect them to a diagnostic node. You only need one input on the safety controller for the entire safe series connection. This saves you time and money during installation, but also when exchanging devices.
Consistent safety Flexi Loop offers a high level of safety in applications up to PL e and SIL3. The simple calculation of the performance level saves time, since the safe series connection individually monitors all sensors connected to it. Flexi Loop also prevents error masking: you can see all errors in the event history.
Simple diagnostics A clear overview on site and in the software: Comprehensive diagnostics of the entire Flexi Loop system is performed via the diagnostics node or the Flexi Soft Designer or Safety Designer configuration software. This enables immediate troubleshooting and machine restart. In addition, diagnostic data can be transmitted to an HMI via the configuration software.

Easy wiring, fast configuration and comprehensive diagnostics

Countless combination options

The Flexi Loop safe series connection is not only an asset for safety switches. It can also be used to combine light curtains and other safety sensors, no matter the manufacturer. Safety sensors on spatially separated system parts can be easily integrated into systems with the help of Flexi Loop. This ensures efficient machine design. The safe series connection facilitates evaluation of sensor data.
Variable combination In addition to the master nodes, Flexi Loop has additional diagnostic, evaluation and auxiliary nodes and can be connected directly to the input of a safety controller. In order to prevent a voltage drop in the series connection, the power calculator determines exactly where to install a module for the power supply.
Convenient connection

You can connect Flexi Loop to the Flexi Soft and Flexi Compact safety controllers and configure them using the configuration software. With master node 1 or 2, Flexi Loop is connected to Flexi Classic via the operating mode selector switch or to the ReLy safety relay using a DIP switch.

Product recommendation RLY3-LOOP100

Quick diagnostics With the help of LEDs, the master node provides an overview for diagnostics, thus ensuring high machine availability. The IO-Link interface of the MSTR2 establishes a connection to the process controller in real time. The advantage: This allows the Flexi Loop nodes to be identified and confirmed without teach-in. The configuration of the master node can be customized.

Connecting sensors in series to enable versatile use


Technical overview

  • Technical data overview

    Technical data overview

    Safety levelPL e, SIL3
    Suitable for

    Flexi Classic

    Flexi Soft

    Safety device connection

    For safety sensor with dual-channel OSSD outputs

    For dual-channel equivalent electro-mechanical safety switch (EMSS)

    Structure of a Flexi Loop cascade


    1 ... 32 Flexi Loop nodes

    0 ... ∞ Flexi Loop accessory nodes

    1 Flexi Loop terminator

    Enclosure ratingIP65, IP67
    Ambient operating temperature–25 °C ... +55 °C
All technical data can be found accompanying the individual product