Experimental Physics and
Industrial Control System

"Kasemir, Kay" <[email protected]> · Thu, 20 Nov 2014 17:48:25 +0000

Hi:

On Nov 20, 2014, at 10:06 AM, Ganesh Jangir <[email protected]> wrote:
> 1. But  I could not figure out  How to form own new IOC and application in v4.  i.e. Something similar to makebaseApp.pl in EPICS v3 base. 
> Do we have to use EPICS base v3 IOC only 
> 
> 2. Is it possible to install and run EPICS v4 without EPICS v3. 
> 
> 3. Where to find beginner material and ppts  for EPICS v4 C++. I am already referring to .http://epics-pvdata.sourceforge.net/gettingStarted.html 
> 
> Thank you
> 
> Regards
> Ganesh 

There is no V4 IOC. EPICS IOCs are just as they have been for decades. If you want an IOC, you still use the plain EPICS IOC.

What V4 offers:
* pvData: A library for creating/inspecting/decoding structured data beyond the dbr_* structures
* pvAccess: A network library for transporting pvData
.. and all that for Java, portable C++, python

pvAccess is a bit like Channel Access, but for pvData.
Also, in addition to get/put/monitor it supports put-with-get, an RCP-type callback.
And the client can ask for just a subset of the pvData structure on the server.

So one can now start to create services on the network that do more than Channel Access.

Yes, you can create a pvAccess server and client without any EPICS IOC.
There is a pvaSrv module that you can add to EPICS IOCs which makes all the ordinary records available via pvAccess, in case you want to transition all the network traffic to pvAccess. At this time, very few of the existing EPICS clients will talk pvAccess, so that's not terribly useful.

There's a pvDatabaseCPP library that helps to create V4 servers. Basically, you create the structure that you want to serve and update it, and pvDatabaseCPP handles the pvAccess interaction.
You can run the result standalone or within an IOC.

>From the recent EPICS meeting, http://irfu.cea.fr/Meetings/epics/program.php, check

* EPICS V4 for SNS Neutron Data
* EPICS V4 for Diamond Detector Data

for examples of adding V4 pvAccess servers to IOC to transport some data that doesn't quite fit into Channel Access.

Thanks,
Kay

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System