Hi Matt,
On 03/25/2015 01:25 PM, Matt Newville wrote:
> On Wed, Mar 25, 2015 at 11:21 AM, Andrew Johnson <[email protected]> wrote:
>
> Recent versions of Base (3.14.11 on) have a CA monitor event type
> DBE_PROPERTY which was intended for monitoring changes to metadata like
> the ctrl variables. 3.14 IOCs don't send out many property events (and
> the PV Gateway doesn't support property subscriptions yet either), but
> as 3.15 and later IOCs come in they make the case for using this quite a
> bit more compelling. I would encourage CA client developers to read the
> tech-talk threads discussing DBE_PROPERTY first though, there are a few
> gotchas.
>
>
> Is it reasonable to simply change the event subscription mask to include
> DBE_PROPERTY by default? Will doing so work (in the sense of "not
> fail"), even though only getting VALUE, LOG, and ALARM events) for older
> iocs and through gateways? If so, that's an easy change to make.
Unfortunately I believe the answer is no, and that wouldn't really make
sense anyway since your DBE_PROPERTY subscription would need to request
a DBR_CTRL data type, but your regular value subscription should for a
DBR_STS data type. The DBR_CTRL types do not include the timestamp, and
would use up extra bandwidth if you used it to get all the extra fields
every time when only the value changed.
A tech-talk search for DBE_PROPERTY will being up a couple of posts by
Kay Kasemir explaining what he found to be the best solution, although I
think a more recent post explained that the CSS code may have turned off
this subscription again for the time being.
- Andrew
--
Light thinks it travels faster than anything but it is wrong.
No matter how fast light travels, it finds the darkness has
always got there first, and is waiting for it.
-- Terry Pratchett, Reaper Man
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- Re: pyepics not updating pv.enum_strs after connection Jameson Graef Rollins
- Re: pyepics not updating pv.enum_strs after connection Matt Newville
- Re: pyepics not updating pv.enum_strs after connection Jameson Graef Rollins
- Re: pyepics not updating pv.enum_strs after connection Matt Newville
- Re: pyepics not updating pv.enum_strs after connection Jameson Graef Rollins
- Re: pyepics not updating pv.enum_strs after connection Matt Newville
- Re: pyepics not updating pv.enum_strs after connection Jameson Graef Rollins
- Re: pyepics not updating pv.enum_strs after connection Matt Newville
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