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I'm looking into designing an IO-Link slave on page 35 of the IO-Link spec they mention Communication Channels. I have received an IO-Link device stack from TEConcept (ST/STM IO-Link partner), I cannot link to it, as it is given by request only. When I run through their stack I don't see this communication type being handled anywhere, just a single UART being utilized without any operating system or threads etc. controlling the flow.

As far as I know the UART protocol doesn't differentiate between cyclic and acyclic communication, only synchronous and asynchronous.

So the design question is how do I handle this ? I'm thinking of using freeRTOS to set up these "Communication channels" / RTOS tasks.

Could it just be that the IO-Link Master handles all this?

Does anyone have experience with designing their own IO-Link device ? My research on the web hasn't been very succesful.

Sorenp
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Usually in the PLC communication world terms cyclic means data that are exchanged each scan continuously, for example IO variables, meanwhile acyclic means you send something on demand also you receive the response, usually this means the exchange of parameter data, configuration, diagnosis,..etc.

What are you looking on particular page of linked spec. is the IO-link protocol on the top of physical protocol. It has nothing to do with UART, it could be any other different hardware protocol below it.

Marko Buršič
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  • Of course the PLC! Perhaps that is my missing link :) I haven't develed into the world of PLC's yet, I think I will start there, thanks for point that out Marko. I think the cyclic and acyclic communication doesn't relate to the embedded software directly. The PLC might well be the "real master" in this case. – Sorenp Feb 11 '20 at 11:42
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The UART is only the physical layer the IO-Link communication is on top of this layer. The stack will handle the the cyclic and acyclic messages transfer on top of it.

Process Data: cyclic message

on request Data: acyclic message

Mike
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