[ag-automation] configuration concept for fieldbus stack

[Dieter Hess]

Hello,
if no cyclic communication is used just don't define TPUs in the configuration and use async read and write services. Modbus is not a typical fieldbus, because there is no difference between cyclic/synchrounus and acyclic/asynchrounous communication. In fact there is only master initiated asynchrounous communication. Cyclic TPUs are just "simulated" by the fddi-driver to let modbus look like a real fieldbus protocol and to get a realistic use case for the fddi. 

Regards

Dieter Hess 

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-----Ursprüngliche Nachricht-----
Von: Robert Schwebel [mailto:rsc at pengutronix.de] Im Auftrag von Robert Schwebel
Gesendet: Dienstag, 10. Juli 2007 17:20
An: Dieter Hess
Cc: ag-automation at www.osadl.org
Betreff: Re: [ag-automation] configuration concept for fieldbus stack

On Tue, Jul 10, 2007 at 10:45:51AM +0200, Dieter Hess wrote:
> here are a general XML-schema for a configuration of a fddi driver, a 
> example for modbus and a description of the modbus profile.

One more comment about the documentation:

> > The parts of the data must be read or written cyclic, that means in 
> > regular time intervals. This data contains the process data.

Modbus is not necessarily cyclic. It should be the choice of the application to trigger a TPU transfer in a cyclic way or not, shouldn't it?

Regards,
Robert Schwebel
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