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FAQ about IO-Link

Further information about IO-Link

What is an IODD?

IO-Link Device Description, the electronic description of the device characteristics: The IODD file provides information for integration into the system e.g. identification, process, and diagnostic data.

Where do you find the IODD?

The IODD for every IO-Link product is available on ifm's website under "Documents & downloads → IODD Downloads".
A manufacturer-independent IODD finder is available on the website of the IO-Link community: www.io-link.com or directly at: https://ioddfinder.io-link.com/#/

Where is the IODD saved?

The IODD is saved in the LR DEVICE parameter setting software or another software for IO-Link device and port configuration tools from ifm provided the IO-Link devices are sold through ifm.

What is a "measured value"?

This is a digital value sent from the sensor to the main system.

Does IO-Link transmit measured values?

If a sensor generates a measured value or determines a process value, this can be transmitted digitally to the controller via IO-Link.

How does the IO-Link measured value differ from a 4 - 20 mA signal?

There are no conversion, scaling or transmission losses.
The entire measured value transmission is digital. Error-prone transmission and conversion of analogue signals are eliminated. The digitally transmitted measured values can be directly displayed in the control room.
Link:  https://www.ifm.com/de/en/shared/technologies/io-link/vorteile/io-link-vorteile

How can wire break be detected with IO-Link?

The IO-Link master checks all IO-Link devices within a communication cycle. If a device does not respond, the wire break is immediately detected and signalled irrespective of the measured value.

How can IO-Link reduce the variety of I/Os?

When using IO-Link the user receives both input and output data via the port of a sensor/actuator device. The typical differentiation of the port as input/output no longer applies.
In standard mode without IO-Link every port of an IO-Link capable device can still be configured as input or output.

What is bidirectional data?

Data that goes in both directions; from and to the IO-Link master.

What is the difference between an A port and a B port?

An A port has an integrated, low-current power supply for  devices; a B port allows a second isolated supply for outputs.

What is an IO-Link master?

The IO-Link master connects one or several IO-Link devices to the gateway in higher-level fieldbus systems.
Click here for the selection of IO-Link masters from ifm: https://www.ifm.com/de/en/category/055/055_010

What functions can the Memory Plug carry out?

For installations without IO-Link the Memory Plug allows transmission of parameters to replacement units. To do so, it reads and saves the data of a connected IO-Link sensor. The saved parameters can be copied to sensors of the same type with factory setting.
Click here for the IO-Link Memory Plug: https://www.ifm.com/de/en/product/E30398

What needs to be done with an IO-Link master before it can be used?

Every master port must be configured by the user according to the requirements of the user's application: master port mode (DI, DO, IO-Link), process data width and data length. Recommendation: activate the device identification for future compatible replacements.
The LR DEVICE software makes this task easier by scanning the network for available IO-Link masters and connected devices.

Click here for LR DEVICE:

How does an IO-Link master know when to download or upload parameters from an IO-Link device?

Whether a port automatically uploads or downloads depends, on the one hand, on the parameter setting of the IO-Link device and, on the other hand, on the configuration of the master port. The parameter setting of the IO-Link device and the master configuration are carried out using an engineering tool such as LR DEVICE.

Click here for LR DEVICE:

How can process data from sensors be integrated in a controller?

The following document describes the integration of process data using the example of ifm pressure and flow sensors.

Integration of IO-Link sensors in a controller.