Tim Mooney wrote:
>
> re...
>
> > I'm working on a download for svx IIe chips here at Fermilab. The
> > chips communicate with the outside world through a port card that sits in
> > a 10 U/vme64 crate. When I download the chips, I write to a register
> > on the port card 15 parameters. Once all of these parameters have been
> > downloaded, I write a command to the port to indicate that I've download
> > all of the parameters and it can then download that information to each of
> > the svx chips.
> >
> > I seek some advise on how to code this problem with epics. I can
> > have a number of generic vmeRecords, one for each of the parameters and a
> > record to tell the port card to "download chips". The order is important
> > and I would prefer not to do code the download this way, as it would be
> > easy for users to change the order of the download.
> >
> > I would prefer to have a single record for the download. However,
> > I'm not sure how this fits into epics. I would like the users to perform
> > caputs for each of the parameters. After all of the parameters have been
> > filled (each would have a field in the record), the user performs
> > another caput to indicate that all of the parameters
> > have been filled and the record can process by writing to the
> > proper vme addresses. This is where I'm not sure how this fits into
> > epics. I only want the record to process (write to port card) once, even
> > while I am performing caputs -- which as I understand causes the record to
> > process.
> >
> > I doubt that this is the first time a problem such as this has
> > been encountered and I would appreciate any advise as to how to best
> > approach this problem.
>
> Well, everybody has their favorite tools. I think I'd use 15 AO (or LO or
> whatever) records to hold and limit check the parameters, and two SEQ records
> to grab the parameters in order and shove them all into a single generic VME
> record which writes them to the hardware.
>
> This solution doesn't defend against the user causing the parameter values to
> be written to hardware before all have been defined. (It would be possible
> with more records to disable the 15-parameter put operation until all 15 AO's
> had been written at least once. Otherwise you probably have to ensure the
> database boots up with legal values.) This solution also doesn't give you any
> simple way of doing complicated parameter checks.
Being faced with the problem of sequencing 16, I made a long sequence
record with 16 outputs ... (CapFast symbol and all).
Let me know if you need it, I can put it on the web.
Maren Purves
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