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<== Date ==> <== Thread ==>

Subject: Re: forcing binary output value at initialization
From: Andrew Johnson <anj@aps.anl.gov>
To: pate@lepton.nmsu.edu, EPICS tech-talk <tech-talk@aps.anl.gov>
Date: Mon, 24 Apr 2000 09:32:04 -0500
pate@lepton.nmsu.edu wrote:
> 
>         Of course, it would be nice to have the best of BOTH worlds:
> bumpless reboot during a "soft" reset, and failsafe condition after a
> "hard" reset.  That requires a method to know what kind of reboot is going
> on.
...
>         Hmmm... Another idea might be for me to have my very own
> definition of the bo record, with initial value "1" instead of "0".  I
> think that would allow me to have the "best of both worlds" as described
> above.  But now I am beginning to speculate, always a good time to end the
> email.

Another perhaps better method would be do modify the xy240 driver/device
support so it requires that a configuration routine called from the
startup script to register each card.  This change probably ought to be
done anyway, moving from the "discovery of cards at fixed addresses"
method used at present.  The point is that it gives you the ability you
need to specify an initial value for the output registers (or AND and OR
masks for them), without otherwise having to change the record code or
your databases at all.

This has the major advantage of being backwards compatible with all the
existing databases out there (I don't mind requiring changes to a startup
script for new software versions, but databases can be a lot harder to
fix).  It would also allow the device support to be extended to make it
possible to request a different split between the numbers of Input and
Output signals, although that's an optional change.  If you made these
changes I would want to see them in the official version.

Are there any other sites out there who have already made similar
changes?  The xy240 is used at many sites, but IMHO the device support
(and EPICS documentation) for it is rather limited.

- Andrew
-- 
Complexity comes for free, Simplicity you have to work for.


References:
Re: forcing binary output value at initialization pate

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