ISEG HV

General introduction:

EPICS uses programs called IOC's to talk to hardware and to publish get/set variables, called PV's (Process Variables), on the network. The built-in IOC in the ISEG CC24 controller is not as well-featured as the SNMP interface, so I have set up an R3B /SOFIA IOC on issdaqpc3 which uses SNMP internally.

The GUI is provided by MEDM, an extension to EPICS. It is very archaic, but simple to use for clicking out GUI's and very simple to automate with simple text-processing tools.

There is also a somewhat graphical commit/restore feature to snapshot all channel PV's, which uses git in the background. The snapshots are local for now, but could be hooked to pushing upstream on every commit.

More specifics:

The IOC runs on issdaqpc3 in the screen session 'iseg'. The script ~/opt/bin/epics_iseg.bash can check and start it as necessary, but is of course not omnipotent, or not as clever as it could be.

Since EPICS talks on the network, one should have an idea about what is going on there. In ~/.bashrc there is:

export EPICS_CA_ADDR_LIST=localhost
export EPICS_CA_AUTO_ADDR_LIST=NO

These make sure that accesses only happen on the interface 'localhost', and no further listing of interfaces is done. (This avoids some annoying warnings when accessing PV's that are visible on more than one interface.) The server settings should also be fixed, but per IOC and not per user, further information here:

https://epics.anl.gov/EpicsDocumentation/AppDevManuals/ChannelAccess/cadoc_4.htm

The GUI is started with:

cd epics/adl/wiener_mpod
./gui.bash

A few PV's do not yet work, they are seen as white boxes, but this should not be a problem...

The lists of PV's can be acquired from the IOC. Open the screen session, make sure the IOC is running (it should say 'epics>' and wait for user empowerment), and run:

epics> dbl > pv.txt

This will create ~/epics/wiener_mpod/iocBoot/iocmpod/pv.txt which is a text-file with all PV names. To get an idea about what they all mean, I would suggest looking in the official ISEG documentation and ~/epis/wiener_mpod/db/*.db files which link PV's to the SNMP data. The GUI can also shed some light. Right-click in an empty space, pick 'PV info', and click on a GUI control to learn which PV is used.

The channels can be given names in ~/epics/wiener_mpod/dbgen/. gen.bash generates some configuration files based on the current fixed crate configuration, and on the file map.txt which contains channel names. Some rudimentary checks are made, such as module and channel ranges, and that no hardware channel is used twice. I just realised that it does not check for duplicate names... Todo.

And lastly, PV's can be accessed on the command-line with:

caget PV-name
caput PV-name value

E.g.:

caget iseg1:0:0:setVoltage
caput iseg1:0:0:setVoltage -20

Note that the names cannot be used, I would need to setup the PV gateway (r3bcagw) for that. Another todo.

For now I have upstreams versions of the various codes on my own gitlab.cern.ch, I hope that they are somehow visible: https://gitlab.cern.ch/htornqvi