Re: EPICS to Python / EPICS to Tcl

[Noboru Yamamoto <noboru.yamamoto@kek.jp>]

Hi,

Rowland, J (James) wrote:
> Hi Tim
>  
> At Diamond we use Python for beamline simulations, some using serial
ptys or socket servers to interface to the standard asyn drivers and
some recent ones implementing asyn ports in Python itself. We also use
some Python device support for waveform calculations, and we have even
written a Python interface to the portable channel access server (not so
useful). It's a good approach for simulations but considering how much
interface code we ended up writing I would recommend the SNL way of
doing things if you can get away with less tight integration with the
database. Your Python script would use the CA client libraries to
monitor PVs on the IOC and write back results. We use that method to
good effect with Matlab. You can easily add a new command to the IOC to
start the Python interpreter in-process like SNL does. I can send you
some examples if they would be useful. I think KEK also had some Python
device support.
>
> James
>

I have wrote a device support routine called devPy.
Currently I just tested ai/ao and waveform record support.
INP or OUT field of these device supports is something like:

        field(INP, "@foo/bah;$(no)?signal=$(signal)")

When this record is initialized it create instance of class bah in a 
module foo with argument specified in INP/OUT field.
At record processing read or write method of this python object will be
called.
I used this device support to support USB device in EPICS. I have Python
interface to this device and was much easier for me to write this 
devPython device support.(and it was fun.)

It works for me and I wanted to extend it futher but cannot find much 
time to it.

If you are interested in this software, I'm very happy to send source 
code to you or put it on the web.

Thanks,

Noboru Yamamoto
J-PARC control group/J-PARC center(KEK & JAEA)
EPICS group/KEK
JAPAN

> ________________________________
>
> From: tech-talk-bounces@aps.anl.gov on behalf of Timothy Madden
> Sent: Mon 04/08/2008 15:56
> To: tech-talk@aps.anl.gov
> Subject: EPICS to Python / EPICS to Tcl
>
>
>
> Folks
>
> I want to make an IOC that does the following:
>
> Serve PV's that call Asyn, They could BI, BO or any standard record.
> Make an Asyn driver that is linked with  a Python or Tcl interpreter.
> The IOC written in C, would then call scripts which could be stored as
> text files on the disk.
>
> A record named "X" would call a script function named "X" and pass its
> PV value to it. Likewise, the output of the script could be passed back
> to the PV value. Python and Tcl interpreters provide ways for C to call
> scripts, pass and retrieve data from scripts. Also, it is not too hard
> to link  an interpreter into a C program. All that is needed is to write
> the ASYN-based C functions that call the interpreter. It could be done
> in Linux or Cygwin.
>
> In this way, one could make an IOC to do whatever one wanted without
> ever messing a C compiler. The user would write a few scripts, make a
> st.cmd file, and a db file. In this way, new IOCs could be very quickly
> developed.
>
> Has anyone already done this?
>
> Tim Madden
>
>
>
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