Messages in this thread | | | Subject | Re: [PATCH v10 0/7] Add Fieldbus subsystem + support HMS Profinet card | From | "Enrico Weigelt, metux IT consult" <> | Date | Mon, 29 Apr 2019 15:54:30 +0200 |
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On 24.04.19 17:10, Sven Van Asbroeck wrote:
> The subsystem is called fieldbus_dev "fieldbus device" because it> abstracts Linux fieldbus clients that want to expose themselves as> e.g. an actuator, motor, console light, switch, ... Sounds a bit confusing. With that description, I'd expect highlevel interfaces similar to LED, input, IIO, etc ... but you're actually implementing an distributed process memory system. This in turn is just a subset of the fieldbus world.
> During one of the eleven review cycles, drivers/fieldbus_dev got> truncated to drivers/fieldbus because the reviewers felt that> _dev was redundant, given the lack of other fieldbus> subsystems. There is at least one: CAN. Sometimes CAN is used in the IEC61158-way, but also completely different, even both in combination.
> These cards are not controllers, but slaves on the bus.
Do they really implement the process memory part or just the lower layer communications ?
> I'm by no means a fieldbus expert. It seems that the term> 'fieldbus' is much broader than these process-memory based> standards?
Yes, indeed.
> I am open to any _concrete_ naming suggestion > that can get consensus. Maybe IEC61158 ?
> I'm a bit confused by Wikipedia's entry for fieldbus. > It suggests that IEC 61158 and Fieldbus are > interchangeable? > https://en.wikipedia.org/wiki/Fieldbus
That's wrong.
> <quote> > Fieldbus is the name of a family of industrial computer > network protocols used for real-time distributed control, > standardized as IEC 61158. > </quote>
IEC 61158 only standardizes one particular approach: the distributed process memory.
> Given that CAN/EtherCAT are not process memory based > (that I know of), the fieldbus_dev subsystem is probably > not a good fit.
ACK. Neither are MVB+friends.
--mtx
-- Enrico Weigelt, metux IT consult Free software and Linux embedded engineering info@metux.net -- +49-151-27565287
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