Re: Bidirectional device support

[Luedeke Andreas <Andreas.Luedeke@psi.ch>]

Hi everyone,

Thompson, David H. wrote:

> [...] It is all a matter of how to package what is in fact a new
> device support function (input) and trick the existing record support
> into posting the monitors while the device support does nothing.
I agree that all this is possible with the existing records. It can be 
handled in the device support.

> [...] I think now that passing input function pointer as an argument to 
> the registration function would be cleaner.  This is something that could 
> be added to core without breaking anything and would provide a standard 
> way to implement bi-directional IO. [...]
>  
I think all information required for the device support should come 
through the link field.
Link Support <http://www.aps.anl.gov/asd/people/anj/lnkSup.html> would 
be a good solution to configure a bi-directional output record
and make the bi-directional feature visible in the database.

I withdraw from my proposal of new records. It would be good if the 
device support
functionality "bi-directional" could be encapsulated, like it's done for 
the asynDriver,
to make it reusable for other device supports.

With a growing number of intelligent devices it would be useful to 
handle all updates
from different origins, some only known to the device itself, in the 
same way as a modification
done by CA clients. Like for CA clients you'll need to handle 
interferences of multiple
processes trying to control the same device but that is not an argument 
against treating
it in the same way.

Cheers
Andreas