IO-Link, HART for discrete?

IO-Link is a point-to-point wiring system intended for smart sensors and actuators.  It communicates over the discrete device’s wires.  This reminds me of HART in the process space where communication is superimposed over the 4-20mA signal wires.  And similar to HART, you can use an IO-Link device in a standard system and a non-IO-Link device in an IO-link system.  In either case, you don’t get the advantage of access to the configuration and diagnostic information over the wire.

You might want to read the press release before proceeding.  There’s also information on the Industrial Ethernet Blog.

IO-Link looks at first blush like it’s competitive with AS-i.  AS-i (AS-interface) is a bus though, albeit a very simple one intended for 1-bit devices like limit switches and on/off valves.  I’m not saying IO-Link is better because it’s for two-bit devices.  (Sorry, I couldn’t resist adding my 25 cents worth of attempted humor.)

So, when would you use IO-Link instead of AS-i?  The answer I got from the folks on the ifm efector stand was “When the sensor or actuator is smart.”  That is, when the device has configuration or diagnostic information to convey.  FDT is used to interface with the configuration or diagnostic information.  (More on FDT and EDDL later.)  Backing up the complementary nature of AS-i and IO-Link, ifm efector demonstrated a link from IO-Link to AS-i on the AS-i stand.  Phoenix Contact demonstrated a prototype of an IP-67-rated link to PROFIBUS on their stand with an IP-20 version described as “planned.”  The official IO-Link story was that products would be available in 2007, but Phoenix said their IP-67 version would be available in the second half of 2006.  SICK said their sensors would be available in the third quarter.  Six different manufacturers demonstrated prototypes of devices on their stands and several more announced devices in the works.

Blogs are normally real-time, but mine seems to have passed through a brief time warp as this information was gathered last Tuesday and just organized today.  Still more from the Fair to come, too.

All was not research by walking around however.  I also had pleasant encounters with colleagues from the past: a few former Wonderware colleagues now with IndX and a few from my Board of Director days on the PTO.  This may just be a fringe benefit of attending, but it’s a very rewarding fringe benefit.