Experimental Physics and
Industrial Control System

Hi Simon,

verify what PYEPICS_LIBCA is pointing to. It is the library which PyEpics
is using to make connections.

From my experience with running PyEpics inside a PythonSoftIoc, the PYEPICS_LIBCA
should point to the same channel access library as the IOC is using.

With 3.14 base I have, it looks like this:

  export PYEPICS_LIBCA=/usr/local/epics/base-3.14.12.6/lib/linux-x86_64/libca.so

In PyEpics you can get the actual channel access library as

  epics.ca.find_libca()


Cheers,
Jarda


On Tue, 26 May 2020, Simon Rose via Tech-talk wrote:

Hello all –

 

I am trying to set up something to do some automated testing of communication with a running IOC with PyEpics, but unfortunately I am running
into some inconsistent behavior which makes it difficult to use as a reliable testing mechanism.

 

Specifically, if I have an IOC (EPICS base 7.0.3.1) up and running on the same machine, and run the following script:

 

from epics import PV

pv = PV(“test”)

assert pv.connect()

 

then most of the time, this works exactly as intended. However, somewhere around 1 in 5 times or so, it fails. I have tried to look at the
network traffic (using Wireshark) between the IOC and the python client, but unfortunately I don’t see a difference between successful and
unsuccessful connection attempts.

 

I am running both IOC and client inside a linux VM on my mac.

 

Any help would be appreciated,

 

Cheers,

 

Simon

Replies:

Re: Unpredictable behaviour with PyEpics Matt Newville via Tech-talk

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