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<== Date ==> <== Thread ==>
Subject: Re: Problem in running simple tutorial problems
From: Matt Newville <[email protected]>
To: Jan Cedric Hönig <[email protected]>
Cc: EPICS Tech Talk <[email protected]>
Date: Tue, 8 Mar 2016 08:54:57 -0600
Hi Jan,


On Tue, Mar 8, 2016 at 7:09 AM, Jan Cedric Hönig <[email protected]> wrote:
Hi all,

I should mention again I have no prior experience in working with epics or any server.

So my naive first thought was that:
In [1]: import epics
In [2]: p = epics.PV('LargeWaveform')
 should start a server and create the PV, which is apparently not the case...?


Ah, sorry for the confusion.  PyEpics is only a client for Epics Channel Access -- it assumes that PVs already exist somewhere.
 
So I started a "SimpleServer" using PCASpy. But here all PVs need to be defined before starting the server (correct?)?

PCASpy is one way to dynamically create Epics PVs.   For most uses of Epics in real production environments, an IOC is set-up to run as the Channel Access server.
 
I was able to modify the data in these pre defined PVs with pre defined array sizes.
Yet I want to be able to store arrays of unknown/changing size in these PVs!

!
So to sum up:
How do I start an epics server? Is it possible to create PVs during operation/how? How do I store arrays of arbitrary size in them?
!


PCASpy is one way to serve Epics PVs.  See https://github.com/paulscherrerinstitute/pcaspy for some good examples and documentation.   

Using an Epics IOC is the more common way, and has many benefits for complex behavior of Records of inter-related PVs.    Setting up an IOC is slightly (OK, more than slightly) more involved, but there are lots of good references for this.   I'm not really an expert on this end of things, but there are many people on this list who are.

--Matt

References:
Problem in running simple tutorial problems Jan Cedric Hönig
Re: Problem in running simple tutorial problems Matt Newville
Re: Problem in running simple tutorial problems Jan Cedric Hönig
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