Experimental Physics and
Industrial Control System

Andrew Johnson <[email protected]> · Tue, 19 Jul 2016 13:38:19 -0500

Hi Hulusi,

On 07/19/2016 01:07 PM, hulusi wrote:
> If there is any way or any tool in order to make database generation,
> i'll be glad to know.

There are many ways to generate databases since a .db file is just a
text file, so you could write programs in almost any language to create
them. However that isn't really what you're asking and generating
databases programmatically is probably a rather advanced topic. While
you are learning EPICS the Visual DCT program is probably the best tool
for you to use.

> The thing is that i can do IOC installation. I mean, I made the database
> structure via VDCT and controlled it by using this path
> "../../iocBoot/iocmyexample" (epics> dbpf ..) .
> 
> What I have done is, I used "dbpf,dbpr" commands to change and look the
> values of PVs. However, i want the program to read the data from the
> supported hardware and in somehow process them (which is basicly to
> say,e.g take the data under the desirable value).

Information about how to use specific EPICS device support is usually
included in the documentation for that device support; each one is
slightly different, so you do have to read the documentation for your
specific device sofware.

> The point that i was in trouble, I could not find how to configurate the
> database with hardware (I have the driver of the hardware). Another
> point is that let's say, i figure the configuration out ; how can i
> allow the database to read the data automatically ? Should i use any
> control loop to do that and where should i do if it is like that ?

You say you have a driver for the hardware, is that an EPICS driver or
is it something like a library from the manufacturer for use from C/C++
code? If you are asking how to write an EPICS device driver there are
some later lectures in the series I pointed you to before about how to
do that, although I think those took place in 2015 so they're on the
other web-page.

Since you seem to be just starting with EPICS you should probably get a
bit more experience using existing device drivers before writing your
own. Have you checked whether the hardware already has an EPICS driver
available? If you can tell us what hardware you will be controlling we
might be able to give more specific advice about how to interface to it.

> If i am not wrong, there is an extension called as "Sequencer" which
> uses "State Notation Language". Does this allow me to generate the
> database by using C language ? If it is like that,how can i use it ?

The Sequencer is a tool that connects to (or is built into) a running
IOC and can read and write data from specific PVs, monitor changes in
the values of those PVs and write to other PVs in response. It does not
create databases, you have to do that yourself. There is a lecture video
that describes the sequencer and writing State Notation Language programs.

> Which tools should i use for whole project (or simple examples,e.g
> reading data,processing them and monitoring on the screen) ?
> 
> Right now, i have these ones : MEDM, Alarm Handler, Probe, Strip Tool,
> Sequencer(but i don't know how to use it,i am searching..). In
> addition,i have these supports : SSCAN, Calc, Autosave (I couldn't
> configurate them with database,e.g i couldn't use "snc" command on the
> IOC application.) .
> 
> I am in trouble about making/configurating whole project's parts together..

You might want to take a look at the Virtual Linac example available
from https://www.aps.anl.gov/epics/download/examples/index.php to see a
more complex configuration that includes an IOC database, sequence
program and a few MEDM screens that all work together.

Unfortunately EPICS has a rather steep learning curve. Creating IOC
applications is not like writing programs in C.

- Andrew

-- 
Arguing for surveillance because you have nothing to hide is no
different than making the claim, "I don't care about freedom of
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Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System