PLCnext Technology Extensions Extensions of the runtime can be integrated into a system in the form of an app. With a PLCnext Technology Extension, the runtime can be extended by the following elements: A process dependent on the runtime (process) A component (component) A Shared Library (library), which usually… Read More
Linux Daemons The support for the Linux Daemons app part type is discarded and removed from PLCnext Technology firmware from version 2025.0. From version 2025.0, the OCI container app part type is supported in the PLCnext Technology firmware. A (Linux) Daemon can be integrated into a system in the form of an app. Read More
Metadata The app description file must contain a JSON object with the name “plcnextapp”, which describes the properties of the PLCnext Technology App: { “plcnextapp”: { “name”: ““, “identifier”: ““, “version”: ““, “target”: ““, “minfirmware_version”: ““, “manufacturer”: ““, “licensetype”: ““,… Read More
Configuration of the PLCnext Technology Runtime Services If you need access or sometimes exclusive access to PLCnext Technology System Services in your app or a PLCnext Technology System Service is not allowed to be running when your app run, you can state this in the “plcnextservices” field of the app_info.json. This is often not… Read More
File and data storage The files of an app container are unpacked into a read only filesystem mounted via SquashFS, so that the apps cannot save/store data/files in their installation directory at runtime. The app description can be used to specify whether a persistent and/or… Read More
Shared Libraries The support for the Shared Libraries app part type is discarded and removed from PLCnext Technology firmware from version 2025.0. It can happen that an exe file integrated in the app container, such as a Command Line Tool, brings its own Shared Libraries with it and needs them for its… Read More
Command Line Tools A Command Line Tools app part makes it possible to integrate functionalities (cmd tools) into a system that are usable via the command line and that can be started from a shell without specifying the full path to the tool executable binary. Necessary additions… Read More
Update Configurations The update process is shown in the following figure: To update an app you need only to install the app container which contains the new app version (without uninstalling the old app version). The update is detected automatically when: An app is… Read More
App container A PLCnext Technology App is stored in a SquashFS container (see Squash FS on Wikipedia). A SquashFS container stores a folder and file structure in a single compressed file. The SquashFS containers of all installed and started apps are mounted by the AppManager in the Linux file system… Read More
Example of a complete app_info.json To make it easier for you to create a correct JSON file, you can use the following JSON schema: { “$schema”: “https://raw.githubusercontent.com/PLCnext/App-Info-Schema/refs/heads/main/app-info-schema.json”, “plcnextapp”: { … } } If you use a code editor that supports JSON… Read More
