Experimental Physics and
Industrial Control System

Michael Davidsaver via Tech-talk <tech-talk at aps.anl.gov> · Thu, 12 Oct 2023 17:19:18 -0700

I think I have allowed sufficient time for someone else to jump to
support pvDatabaseCPP...

On 10/4/23 08:38, Ignacio Arriagada via Tech-talk wrote:

Hello Tech-Talk!
I'm trying to integrate PVAccess (or PVXS) capabilities into an old IOC. *
*

  * *What would be the best way to exchange data between the old DBRecords and the new PVRecords with custom data structures, within the same IOC*?

The PVRecord c++ class is specific to the pvDatabaseCPP modules, which
I do not recommend for new code.

I do *not* see PVRecord as a replacement for the process database.

imo. the name "PVRecord" is a misnomer.  It has no linking or scanning
facilities.  And only simple locking.  It is a fairly low level tool
comparable to the "casPV" class from PCAS, or the SharedPV class from
"PVXS".

  * Do I need to set up a pvClient within the same ioc?
  * Does the exchange need to be done via PVAccess connections or is there an internal way of doing it?

Through PVAccess.  "PVRecord" is an interface to a PVA server.

I've been reading Marty Kraimer EPICSV4 developers guide <https://mrkraimer.github.io/website/developerGuide/developerGuide.html> and associated git examples. I'm also consulting Michael Davidsaver's PVXS documentation but it is not clear to me yet how to accomplish this. Are there other resources or examples that I could access regarding this topic?

Unless you have some special need, I would suggest writing an "normal"
EPICS driver (w/ device support, .db files, etc.).

If you do want something more, like more complex data structures, I
would suggest first looking into QSRV groups.

https://mdavidsaver.github.io/pvxs/qgroup.html#understanding-groups

Or if you find something some data structure or operation which
can't be mapped to the process database, you could look into SharedPV.

eg. https://mdavidsaver.github.io/pvxs/example.html#mailbox-server

This example sets up a standalone server.  It is also possible to
add a SharedPV alongside (but separate from) the records served
by QSRV2.

https://mdavidsaver.github.io/pvxs/ioc.html#adding-custom-pvs-to-server

Thank you all in advance,
Regards,
Ignacio

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System