Saturday, November 10, 2012

What the heck is IO-Link?

What is IO-Link? 

If you haven't heard about this technology, you will!  It is currently being used in Europe, and coming to North American Automation Distributors.  IO-Link began in 2010 and its organization is comprised of leading Automation providers determined to provide a full range of sensor, actuator, and controller technology in support of a new concept.  IO-Link is a neutral interface and is fieldbus independent. This technology is used in automation systems below the IO (PLC or Remote I/O) level for individual linking of field devices (sensors/actuators).

So what, you're probably thinking? Well, some of the benefits of IO-Link are the reduction of wiring, labor, PLC I/O and inventory.  Since IO-Link is physically comprised of a 3-conductor design, sensors, including analog versions, will only require 3-conductors.  Additionally, diagnostic information is reported on the device's condition.  The diagram below shows the pin-out description.
Pin 1 - 24VDC+, Pin 2-open, Pin 3-DC-, Pin 4-IO Link data or SIO (standard I/O mode) **note PNP outputs only**

The IO-Link Master will coordinate the sensing device's value with a register in the fieldbus controller (PLC or remote I/O node).  If you decide to replace an IO-Link sensor with a standard PNP sensor, it will operate with no problems.  However, automatic ID and other communication functions will not be available. Once a replacement IO-Link device is installed, the Master will recognize and report the data to the control system.

Speaking with a group of our automation specialists, we brought up a few of the following points:
  • Is the IO-Link organization designing something that isn't needed?
  • Are we saving I/O points on remote I/O or PLC nodes (since we have to use a Master in place of the I/O module)?
  • Will the extra cost of IO-Link devices be worth their benefit?
  • Will IO-Link users need to configure a sensing device remotely?
  • If IO-Link is so great, why isn't it being accepted quicker?

IO-Link FAQ, answers some of these...

At Standard Electric Supply Co, we represent the following IO-Link providers: Lutze, Pepperl+Fuchs, Schneider Electric, Sick, Siemens & Wago

For additional details on architecture, please refer to IO-Link's website:

IO-Link Members:

Please contact Standard Electric Supply Co for additional information at

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