An e3 IOC

The following assumes that you already have EPICS base, require (3.3.0 or later as the module version has been left out in the require call1), and iocStats installed.

An IOC in e3 is typically (minimally) just a startup script which is passed to softIocPVA.2

Create the startup script

A very minimal startup script to illustrate what a ‘typical’ IOC in e3 looks like:

[iocuser@host:~]$ touch st.cmd
[iocuser@host:~]$ echo "require iocstats" >> st.cmd  # iocInit() is called implicitly

Start the IOC

[iocuser@host:~]$ /opt/epics/base-7.0.6.1/require/4.0.0/bin/iocsh st.cmd

Note

In require 4.0.0, the startup utility was renamed to iocsh. If you are using an older version of require, you should use iocsh.bash instead.

Conventions

To set correct PV names, the environment variable $IOCNAME must be set before starting your IOC. (where the easiest option is to just write export IOCNAME=yourIocName prior to starting the IOC).

Thus you may end up with something like the following:

Directory

[iocuser@host:~]$ tree e3-ioc-test
e3-ioc-test
├── README.md
├── env.sh  # depending on the version of require you are using
└── st.cmd

Startup script (st.cmd)

[iocuser@host:~]$ cd e3-ioc-test
[iocuser@host:e3-ioc-test]$ cat st.cmd
require common
require module

epicsEnvSet(${IOCNAME},                 "${IOCNAME:NoName}")

iocshLoad(${module_DIR}snippet.iocsh,   "IOCNAME=${IOCNAME}")

iocInit()

dbl > PVs.list
date

Note

Note that st.cmd must end with a newline—this will be explained in The require module.

---

1

In version 3.3.0 of require, version pinning became optional; i.e. from require MODULE,MODULE_VERSION to require MODULE[,MODULE_VERSION].

2

ESS only uses EPICS base 7 for production, and thus only uses softIocPVA. Earlier iterations of e3 also supported use of softIoc, but that functionality has been removed from scope.