Create and Run a Simple EPICS IOC¶

This tutorial will guide you through creating your first EPICS Input/Output Controller (IOC) on your Raspberry Pi. An IOC is the core component that hosts process variables and serves data to EPICS clients.

Step 1: Create IOC Application Directory¶

First, create a dedicated directory for your IOC application:

cd ~
mkdir myioc
cd myioc

Step 2: Generate Base App and IOC Skeleton¶

Use the EPICS makeBaseApp tool to generate the application structure:

/home/debian/Apps/epics/base-7.0.8/bin/linux-arm/makeBaseApp.pl -t example myioc

This creates the basic directory structure and Makefiles needed for an EPICS application.

Step 3: Compile the Application Source¶

Navigate to the source directory and compile the application:

cd myiocApp/src/
make

Step 4: Build the Application & Install Components¶

Move up one directory level and build the complete application:

cd ..
make

This compiles all components and prepares the IOC for database and boot configuration.

Step 5: Add the Database File¶

Create a database file that defines your process variables (PVs):

mkdir -p ~/myioc/db  # Create db directory if it doesn't exist
cd ~/myioc/db
nano myioc.db

Add the following content to define two test records:

record(ai, "test:example1") {
  field(DESC, "Test input 1")
  field(VAL, "42")
}

record(ai, "test:example2") {
  field(DESC, "Test input 2")
  field(VAL, "13")
}

After saving the database file, rebuild the application:

cd ~/myioc/
make

Step 6: Generate the IOC Boot Directory¶

Create the IOC boot configuration:

/home/debian/Apps/epics/base-7.0.8/bin/linux-arm/makeBaseApp.pl -i -t example myioc

When prompted for the application name, simply press Enter to use the default (myioc).

Step 7: Manually Create envPaths File¶

The envPaths file sets up environment variables for your IOC:

cd ~/myioc/iocBoot/myioc
nano envPaths

Add the following content:

epicsEnvSet("TOP", "/home/debian/myioc")
epicsEnvSet("IOC", "myioc")
epicsEnvSet("ARCH", "linux-arm")

Make the file readable:

chmod +r envPaths

Step 8: Edit st.cmd¶

The startup command file (st.cmd) configures and starts your IOC:

nano st.cmd

Note: There might be prefilled content in st.cmd. If needed, remove the existing file and create a new one.

Add the following content:

#!../../bin/linux-arm/myioc
< envPaths
cd "/home/debian/myioc"

## Register all support components
dbLoadDatabase("dbd/myioc.dbd", 0, 0)
myioc_registerRecordDeviceDriver(pdbbase)

## Load record instances
dbLoadRecords("db/myioc.db", "user=debian")

cd "/home/debian/myioc/iocBoot/myioc"
iocInit

Make the file executable:

chmod +x st.cmd

Step 9: Run the IOC¶

Start your IOC:

./st.cmd

You should see initialization messages ending with:

iocRun: All initialization complete

Your IOC is now running and serving the process variables you defined.

Step 10: Test from Separate Terminal¶

Open a new SSH session to your Pi and test your IOC:

caget test:example1
caget test:example2

Expected Output:

test:example1                          42
test:example2                          13

Success!¶

Congratulations! You have successfully created and run your first EPICS IOC. Your IOC is now: - Serving two process variables (test:example1 and test:example2) - Accessible from EPICS clients on your network - Ready for expansion with additional records and functionality

Next Steps¶

With a working IOC confirmed, you're ready to integrate real hardware:

Next tutorial: Flash Arduino SCPI - Prepare your Arduino device with SCPI communication protocol

This will enable your IOC to communicate with physical hardware devices through serial communication.