Experimental Physics and
Industrial Control System

Jan Cedric Hönig <[email protected]> · Tue, 08 Mar 2016 14:09:59 +0100

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...?

So I started a "SimpleServer" using PCASpy. But here all PVs need to

be defined before starting the server (correct?)?

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?

!

From what I gather from the wiki all this should be possible, but I

seem to be missing a step...

(I'm working locally so firewall should not be an issue for now...)

Thanks in advance,
Jan

On Mon, 7 Mar 2016 10:44:45 -0600
 Matt Newville <[email protected]> wrote:

Hi Jan,

On Mon, Mar 7, 2016 at 7:43 AM, Jan Cedric Hönig <
[email protected]> wrote:

Hi,

I'm planning to use epics, but I"m stuck right at the beginning.
I work on scientific linux 6 so first I start python:
ipython
Python 2.7.5 (default, Jun  5 2014, 14:38:05)

Then I try simple epics commands:
In [1]: import epics
In [2]: p = epics.PV('LargeWaveform')

In [3]: p.connect

Out[3]: <bound method PV.connect of <PV 'LargeWaveform': not

connected>>

But I am unable to connect any of my PVs. Am I doing something

wrong?

'connect' is a method of a PV.  To run this method, add parens:
  p.connect()

The connection should happen automatically and soon, so that you

don't need

to explicitly run the connect method, and can just access the data:
  p.get()

You can also checked the value of `p.connected`, which will be True

once

(and if) the PV is connected.

--Matt

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System