Keep your eyes open in data communications!

IO-Link: The new standard at the fieldbus level

The IO-Link interface in the pico+ sensors gives you everything you need to implement continuous communication on all levels of the system architecture, right down to the sensor.  In this way, both machinery and equipment can be run in a more productive manner. IO-Link can enormously simplify the startup and maintenance of either a machine or appliance.

IO-Link in detail

Following every switch-on, pico+ is in the SIO mode (Standard I/O mode) and functions just like any normal ultrasonic proximity switch with push/pull output stage.

With the wake-up signal, an IO-Link enabled controller can transfer the pico+ into the communication or IO-Link modes. The controller can now exchange both process and service data with the pico+.

An IO-Link master can have one or a number of inputs and outputs. Only one IO-Link device is attached at each input/output. A standard 3-wire cable joins up the sensors and actuators. This non-shielded line can be up to 20 metres in length.

A mixed operation is possible thanks to complete compatibility to the SIO mode (Standard-IO mode): at a master a number of sensors and actuators can be run in the IO-Link and others in the SIO mode.

Continuous communication permits process/service data to be transmitted between sensors/actuators and the controller.

Filling systems equipped with IO-Link

An IO-Link system consists of IO-Link devices – mainly sensors, actuators or combinations of them – a standard 3-wire sensor/actuator cable and an IO-Link master.

More information on the IO-Link can be found in

The advantages of IO-Link:

  • In the IO-Link mode the distances measured are cyclically transmitted to the master; thus the IO-Link mode can replace an analogue output at no significant expense!
  • Following a sensor failure, the controller can automatically re-load all the settings into the new sensor.
  • Reduction in planning outlay achieved from a standardised integration of devices into the controller via a manufacturer-independent IODD description file
  • Reduced startup times thanks to a centralized provision of data and parameters in the controller
  • Greater equipment availability levels coming from maximum transparency and system-wide diagnosis all the way down into the device itself

Push-Pull output stage permits switching from SIO mode to IO-Link mode

Example of the system architecture

Product name


Baud rate

COM 2 (38,400 Bd)

Format of process data

16 Bit, R, UNI16

Content of process data

Bit 0: Q1 switch status; bits 1-15: Distance value with a resolution of 0.1 mm

ISDU parameter

Switch point 1, return detect point 1, switch point 2, return detect point 2, foreground suppression, (NC/NO) operation, filter, filter strength, switching delay, interference noise suppression,

System commands

activation/deactivation of teach-in on pin 5 teaching a switch point, teaching switch point + 8%, teaching a reflective barrier, loading factory settings

Common IO-Link-specific data

Download IO-Link IODD library