Operating system

The PLCnext Technology control platform is based on a Linux® operating system with the OSADL real-time patch. Linux® is a highly reliable, open source operating system suitable for applications that require a high stability. A wide range of open source software is available for the Linux® operating system, which is supported by a large community of users and developers.

You can also use this open software, software blocks, and technologies for your PLC applications (e.g., SQL server). PLCnext Technology uses the Linux operating system and extends it by the functions of a PLC such as the cyclic processing of tasks and cycle-consistent data exchange. Core changes or extensions are not possible. To add functions to the system, the user must compile and, if necessary, execute installations with root rights.

The operating system features the following components and services:

Firewall (can be configured via the Web-based Management)
OpenVPN
IPsec strongSwan
SSH/SFTP
NTP (Network Time Protocol)
DNS

Text editors

Nano and Vim come pre-installed on the controller as text editors (Note: from firmware 2025.0, the Vim editor has been dropped for security reasons).

While you are connected to the controller via the SSH console, you can call the desired editor via the command line. To open a file with the desired editor, enter nano <file name> or vim <file name>.

Nano

The Nano text editor is easy to use and is therefore recommended for less experienced users. Find an introduction and documentation of features at the GNU nano website.

Vim

Valid for firmware 2019.0 LTS up to 2024.6

The Vim text editor has an extended range of functions and is a popular editor in the Linux® environment. Find an introduction and documentation of features at the Vim website.

Controlling the firmware via commands

From firmware 2025.0

The plcnext service in the systemctl utitily out of the systemd Linux® suite controls the firmware.

Use the following commands:

Shell command	Description
`sudo systemctl stop plcnext`	Stops all PLCnext firmware processes
`sudo systemctl start plcnext`	Starts all PLCnext firmware processes
`sudo systemctl restart plcnext`	Restarts all PLCnext firmware processes

Firmware 2019.0 LTS to 2024.6

The plcnext script in the /etc/init.d directory controls the firmware.

Use the following commands:

Shell command	Description
`sudo /etc/init.d/plcnext stop`	Stops all PLCnext firmware processes
`sudo /etc/init.d/plcnext start`	Starts all PLCnext firmware processes
`sudo /etc/init.d/plcnext restart`	Restarts all PLCnext firmware processes

Firmware management

Updating the firmware

You can update the firmware conveniently by means of the Web-based Management on your controller. These are the steps:

Open the regarding Web‑based Management page on your controller:
- In the WBM 2, navigate to the System → Update section.
- In the legacy WBM (up to firmware 2024.6) navigate to the Administration → Firmware Update section.
Follow the instructions given there.

Note: If the boot process failed five consecutive times then the inactive and the active boot partition will change their roles. This behavior has been implemented to keep the PLCnext Control device accessible even if the firmware update fails.

The behavior can also occur when the boot process is interrupted e.g. by power loss. In this case you will observe that the PLCnext Control boots with its previously installed firmware version. To prevent such unintended firmware downgrades, Phoenix Contact recommends that after a finally successful firmware update, the same firmware should be installed once again. This way both the active and the inactive boot partition will contain the same firmware version.

Note: In order to update to a current firmware release, a firmware version 2022.0 LTS or newer must be installed on the controller. Firmware versions 2021.9 and before will not accept the *.raucb firmware update file.

Coming from devices running on 2019.0 LTS up to 2021.9 firmware, first update to the 2022.0 LTS release.
After restarting under firmware 2022.0 LTS, update to the newer release.

Updating from firmware versions before 2019.0 LTSUpdating from firmware versions before 2019.0 LTS

In firmware versions before 2019.0 LTS (the naming back then was like "1.02"), you can start the firmware update via the sudo update-plcnext shell script, which you will find in the file system of the controller.

Download and unzip the firmware *.zip file (see Tool downloads).
For older firmware, run the *.exe setup file to extract the *.raucb update file; newer firmware already contains the naked *.raucb update file.
Open an SFTP client software (e.g., WinSCP) and log in to the controller as the admin user (see Connecting to the controller).
Security note: Use the default admin user password only for initial access and change it as soon as possible!
Copy the *.raucb update file to the /opt/plcnext/ directory (this is the home directory of the Linux® admin user).
Open the shell using a command line tool (e.g., PuTTY or Tera Term).
Log in to the controller as the admin user here as well.
Issue the update command; the name of the update script is the same for every controller:
sudo update-plcnext.
- The script is available in the directory under /usr/sbin/.
- Under /usr/sbin/, you will also find symbolic links with the respective product designation in the name, e.g., sudo update-axcf2152.

The script executes the following operations:

Stopping the PLCnext Technology process.
Performing the firmware update.
Rebooting the system and deleting the firmware container.

Downgrading the firmware

For downgrading to a former firmware version (minimum is 2019.0 LTS), you can use the firmware update feature of the Web-based Management on your controller and just pick a release version prior to the one that is installed.

These are the steps:

Reset to Default setting Type 1 (see the regarding description).
Open the Web‑based Management on your controller.
In the WBM 2, navigate to the System → Update section (in the legacy WBM to the Administration → Firmware Update section).
Follow the instructions given there.