Re: DRVL, DRVH, HOPR, LOPR

[Gary Croke <gcroke@jlab.org>]

Just a thought, but if it is important to know whether these fields have been deliberately set (as opposed to default), you could set a flag in
another, unused field, e.g. DESC.



On 02/01/2012 09:32 AM, Abadie Lana wrote:

Hi all
Thanks to all your replies.
So no real mean to know if it was  really set or a default value, except for some alarm fields which then displays NaN. 
Thanks
Lana
-----Original Message-----
From: Luedeke Andreas [mailto:andreas.luedeke@psi.ch] 
Sent: 01 February 2012 15:25
To: Abadie Lana
Cc: tech-talk@aps.anl.gov
Subject: Re: DRVL, DRVH, HOPR, LOPR

Questions: 
1. how does one (especially the client) know that the limits are really set? And not default values.
2. if it performs a check that HOPR!=LOPR then what if one defines an upper limit (but does not need a low one) and vice-versa.

to 1.)
As pointed out previously: The client does not know it. 
Of course DRVH/L are already handled by the record: if DRVH=DRVL=0 then only a "0" can be written to the hardware But HOPR and LOPR are not used by all clients. 
If you want to use them in any client, take care that they are set for ALL records that are meant to be used by any client.

to 2.)
The only way to allow HOPR and LOPR to be set individually would be to change the default: HOPR=+Inf and LOPR=-Inf.
But this is not really useful: e.g. if you want to present a control slider you need two limits to just show it.
And if just one client has a problem with one unset limit, then you'll need to set all limits.


Just drop the idea of not setting HOPR or LOPR for any relevant PV.
Every PV has to have a valid range.


Andreas

--
Dr. Andreas Luedeke, SLS Operations Manager, Tel:+41-56-3104002 Andreas.Luedeke@psi.ch, http://people.web.psi.ch/luedeke