Re: Periodically calling shell functions in an IOC

["Hu, Yong via Tech-talk" <tech-talk at aps.anl.gov>]

Hi Andrew W.:

 

If you do not want to hack “streamReload”, you may try this: https://github.com/NSLS-II/elauncher

 

It is an EPICS device support for easy script launcher: one can run a Python (or shell, or anything you can use in a Linux terminal) script inside an IOC through a bo record. Michael Davidsaver developed it at NSLS-II a few years ago, specifically for use cases like yours.

 

You can change how fast you want to execute your script by simply changing the field of SCAN either from a command caput or from a CS-Studio button:

 

caput elauncherTestShell.SCAN 3

caput elauncherTestShell.SCAN Passive

 

caget -d GR_ENUM elauncherTestShell.SCAN

elauncherTestShell.SCAN

    Native data type: DBF_ENUM

    Request type:     DBR_GR_ENUM

    Element count:    1

    Value:            1 second

    Status:           NO_ALARM

    Severity:         NO_ALARM

    Enums:            (10)

                      [ 0] Passive

                      [ 1] Event

                      [ 2] I/O Intr

                      [ 3] 10 second

                      [ 4] 5 second

                      [ 5] 2 second

                      [ 6] 1 second

                      [ 7] .5 second

                      [ 8] .2 second

                      [ 9] .1 second

 

 

Cheers,

Yong

 

 

From: Tech-talk <tech-talk-bounces at aps.anl.gov> on behalf of "tech-talk at aps.anl.gov" <tech-talk at aps.anl.gov>
Reply-To: Ralph Lange <ralph.lange at gmx.de>
Date: Thursday, October 14, 2021 at 4:56 AM
To: "tech-talk at aps.anl.gov" <tech-talk at aps.anl.gov>
Subject: Re: Periodically calling shell functions in an IOC

 

On Wed, 13 Oct 2021 at 22:45, Wang, Andrew via Tech-talk <tech-talk at aps.anl.gov> wrote:

I have a question regarding the use of shell functions with in the IOC shell. There is a shell function from StreamDevice called streamReload that I am interested in using periodically like every 30 seconds. What is the preferred method, if there are any, for doing so? Also, is there a potential way for calling that shell function within the SNL sequencer?

 

This is unusual as operating mode. The reload function is intended for development / rapid prototyping (testing a protocol change without rebooting the IOC).

So - please be careful with respect to possible side effects: What happens if the protocol file gets corrupted, a typo is being introduced, the disk (or nfs) is down etc. How do you detect such a situation? How do you fix it?

Needs testing.

 

Cheers,
~Ralph