Experimental Physics and Industrial Control System
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On 1/2/23 3:53 PM, Hu, Yong via Tech-talk wrote:
Michael, we
are talking about fields here. So “det1:NELM.RTYP” itself is
not valid.
If "det1" is an IOC record, then "det1.RTYP" is definitely a PV name
that the IOC will respond to. "RTYP" is a record
attribute that the IOC adds
to all record types, which returns the name of the record
type. Some CA client applications (e.g. MEDM, capr.pl,
CS-Studio's
pvtree) query that attribute automatically for some/all of the
channels they connect to, so a field alias such as the one suggested
could result in the IOC seeing requests for that PV name.
Michael's question is thus a valid one. For a simple/naive
implementation of this feature the answer might be that the channel
name “det1:NELM.RTYP” would
time out, and such field aliases just wouldn't support the capr.pl
or pvtree applications at all in that case. That might be
acceptable, but I would want to be shown that any implementation
would not significantly increase the amount of work that the IOC's
CA Search thread has to do.
- Andrew
On 12/28/22 03:47, Zimoch Dirk
via Tech-talk wrote:
> At the moment, that is not possible. I had planned
for quite some time to implement that.
> ... But I don‘t know what the core developers think
of this.
Aliasing fields seem like a reasonable feature. Although
it isn't yet clear
to me how this would work in detail. eg. to take an
example from below.
>> alias("det1.NELM", "det1:NELM")
What would "caget det1:NELM.RTYP" return?
There may also be complications depending on what changes
to the
'struct dbBase' tree would be needed.
> Dirk
>
>> Am 20.12.2022 um 19:50 schrieb Li, Ji via
Tech-talk <tech-talk at aps.anl.gov>:
>>
>>
>> Hi,
>>
>> I'm trying to access record fields as PVs using
alias command, such as:
>>
>> alias("det1.NELM", "det1:NELM")
>> alias("det1.TSEN", "det1:TSEN")
>>
>> The IOC didn't report errors, but apparently they
all pointed to det1 as the change to det1 appeared on
these aliases, and vice versa, and this was proved by
dbla.
>>
>> If alias command is not the right choice, are
there any ways to create aliases/dummy PVs for fields?
>>
>> Best,
>> -Ji Li
>>
--
Complexity comes for free, Simplicity you have to work for.
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- Replies:
- Re: Possible to create aliases for record fields? Michael Davidsaver via Tech-talk
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- Re: Possible to create aliases for record fields? Michael Davidsaver via Tech-talk
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