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Re: Questions: readPin() implementation && OPC UA I/Os integration [message #1846988 is a reply to message #1846987] |
Mon, 11 October 2021 12:39 |
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Hi Tuojian,
the reason for this difference is that we have in sysfs as well as in other IO interfaces an handler which is scanning the inputs and if needed generates IND events on the IX blocks. In order to not interfere between the two threads the readPin, which is triggered by the REQ event is in general doing nothing just assuming that the handler has recently updated the pin and therefore just send a CNF event. While looking at the code I noticed that there is a hardoced 10ms scanning loop. I remember that I never liked it. But we never found time to improve it.
The best would be to move the whole code to the new configurable IO concept that Johannes Meßmer developed in his Bachelor thesis. You can already see it applied in the embrick and new wago pfc implementation. An overview can be found in this paper: https://ieeexplore.ieee.org/abstract/document/8247577
I think this could also be the starting point for an OPC UA based IO concept. Or am I wrong.
Cheers,
Alois
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