Guide de configuration Iono Pi + CODESYS

Turning a Raspberry Pi into an Industrial PLC

Introduction

An entry-level compact PLC might cost a few hundred dollars, but the software to program it can cost even more, sometimes as an annual subscription. For a student just trying to learn how a PLC works, that price tag is a real deterrent.

That was the exact roadblock I encountered during my instrumentation, automation, and robotics training. Brands like Allen-Bradley, Siemens, and ABB make fantastic equipment, built to last decades on a factory floor. But none of it was designed for a hobbyist’s workbench.

I had to find a compromise: something serious enough to let me learn real concepts—IEC 61131-3 standards, ladder logic programming, task cycles—but also affordable.

I finally discovered that you can transform a Raspberry Pi into a PLC. Specifically, I found that Sfera Labs sells a Raspberry Pi-based PLC called the Iono Pi. It’s a Raspberry Pi 4 with an Input/Output module that combines several digital and analog input lines, all housed in a DIN rail enclosure. It features 6A relays, 0-40V inputs, open collector outputs, and a real-time clock. It’s programmable via CODESYS, which is free in development mode (with a 2-hour runtime limit, but by that point, I’d be willing to pay for a license if needed).

All I had to do was make it work.

Materials

The model I use is an IPMB20T48: an Iono Pi equipped with a Raspberry Pi 4 Model B with 8GB of RAM.

https://sferalabs.cc/product/iono-pi/

I purchased a bench power supply to power it, but initially, I powered it using a simple 12V power supply.

Operating System

Like any computer, it needs an operating system. Contrary to what I initially thought, this choice is not trivial.

Based on my understanding, Raspberry Pi OS (Legacy, 64-bit) Lite is the correct choice.

There are three key parts to that name, and each one matters:

• 64-bit, because CODESYS requires its runtime to match the system. There are three variants: Raspberry Pi SL (32-bit single-core), Raspberry Pi MC SL (32-bit multi-core), and Raspberry Pi 64 SL (64-bit). Choosing the wrong one means starting over from scratch. This is crucial to monitor.

• Lite, meaning without a graphical interface. The Raspberry Pi 4 already gets quite hot inside a closed DIN rail enclosure—Sfera Labs even recommends throttling its frequency. A graphical desktop runs dozens of unnecessary services and generates extra heat. As I’m comfortable with the command line, a graphical interface offers no benefit here. Therefore, the Lite version is perfect for my needs.

• Legacy, finally. This term can be confusing: it doesn’t mean an obsolete version, but the previous stable release—Debian 12 “Bookworm”—while the standard option now points to Debian 13 “Trixie”. This choice isn’t dictated by my Iono Pi, but by CODESYS: its runtime isn’t yet validated on Trixie. Bookworm remains the tested version and the one on which this entire guide has been verified.

Installing the Operating System

I prefer to use the dedicated Raspberry Pi Imager software—it’s simple and easy to use.

https://www.raspberrypi.com/software/

Once installed, open the software.

Choosing the Device

I first selected my board model:

Choosing the OS

Then, in the OS section, I navigated to the Raspberry Pi OS (other) subsection and chose:

Storage Device

You’ll need an SD card reader for the software to detect your Raspberry Pi’s SD card.

Once selected, we can proceed to the Customization section.

Customization

Afterward, simply follow the software’s instructions to write the image to the SD card.

Insert and Power ON

Remove your SD card from your computer and insert it into the Iono Pi.

Connect the power supply to the VS+ and VS- terminals.

A blue LED on the front panel will light up when power is present.

After the device boots (this may take a minute or two), it should appear on your network with the hostname you set during customization (e.g., IONOPI).

Take note of the IP address and proceed to the SSH connection in the next section."

SSH Connection

Now that the Iono Pi is powered on and connected to the same network as your computer, you can connect to it via SSH to continue the configuration.

Use one of the following commands to connect via SSH to your Raspberry Pi from a terminal (PowerShell, Command Prompt, or Windows Terminal).

# Basic SSH connection
ssh username@192.168.1.100

# Specify a non-default port (if you changed it)
ssh -p 2222 username@192.168.1.100

# Connect with verbose output for troubleshooting
ssh -v username@192.168.1.100

Replace:

• username with the username you created during the OS customization.
• 192.168.1.100 with the actual IP address assigned to your Raspberry Pi on your network.

ssh-keygen -R hostname

Afterward, you will be prompted to enter the password for the username you specified. Use the password you configured during the Raspberry Pi OS customization.

When you have a active SSH connection you should see a similar screen has mine.

System verification

Before anything else, confirm that the image written to the SD card matches what you think it is. Four commands, four distinct pieces of information.

uname -m                 # → aarch64 (64-bit; confirms the runtime choice)
uname -a                 # → Linux IONOPI 6.12.93+rpt-rpi-v8 ... aarch64
cat /etc/os-release      # → Debian GNU/Linux 12 (bookworm)
cat /etc/rpi-issue       # → image from 2026-06-18, stage2 = Lite version

Update the system and add missing tools

sudo apt update && sudo apt full-upgrade -y

• Update refreshes the list of available packages.
• Full-upgrade installs the updates, including those that require adding or removing dependencies.

sudo apt install -y i2c-tools

This package provides i2cdetect, i2cget and i2cset, which will be needed to confirm that the real-time clock appear on the I²C bus.

Enable the hardware buses

sudo raspi-config

Navigate to Interface Options, then enable:

These options write dtparam=spi=on and dtparam=i2c_arm=on into the configuration file, you can also add them by hand, which amounts to the same thing.