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

Subject: Re: propagating value upward at init
From: "Liu, Gongfa" <gongfa.liu@desy.de>
To: Emmanuel Mayssat <emmanuel_mayssat@lynceantech.com>
Cc: tech-talk@aps.anl.gov
Date: Fri, 02 Oct 2009 09:01:43 +0200

Hi, Emmanuel,

Emmanuel Mayssat wrote:
Hello,

I hope you are all doing well.
I may have asked this question a months ago, but ...

I have the following DB processing scheme

AO (high level PV name) --> AO ( hardware PV name) ---> hardware ---> AI (hardware PV name) --> AI (high level PV name)

When I set the first AO, the value is propagated to the other one (on OUT field), then to the hardware and finally read back on both of the AI.

The issue is that when I reboot the IOC, the first AO is reset to 0.
Ultimately I would like it to be set at current value (read hardware first and then set value accordingly).

In the device support, set the return value of init_record() to 0, then in the ao record support, its init_record will computes the VAL form RVAL using the algorithm:
VAL = ((RVAL+ROFF) * ASLO + AOFF) * ESLO + EOFF

please refer to "EPICS 3-14 Record Reference Manual"

Good luck,

Gongfa


With AI with a PINI=YES, I can see what the hardware value in both AI.
How can I load the CURRENT hardware value in the 1st AO at init?

( I use base < 3.14.11, so not so easy to use multilayer aliasing!!)
--------------------------------------------
Additionally could someone give an example where the DOL + OMSL field are commonly used?
I wonder what the practical purposes of those fields are.

Regards,
--
Emmanuel



--
----------------------------------------------------------
Gongfa Liu                         MKS-2, DESY
phone:  +49-40-8998-1642           Notkestr. 85
fax:    +49-40-8998-4388           22607 Hamburg
e-mail: gongfa.liu@desy.de         Germany
----------------------------------------------------------

References:
propagating value upward at init Emmanuel Mayssat

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