App installation states

PLCnext Technology Apps must be installed and uninstalled using either the PLCnext Store or the web-based management (WBM) hosted on the controller. In the background, both the PLCnext Store and the WBM interact with the AppManager on the controller to handle the app installation and run states.

A PLCnext Technology App can have one of the following app installation states:

• Installed:
  • The app SquashFS container file is stored on the controller in the app's installation folder
    /opt/plcnext/installed_apps
  • App install parts are activated on app installation.
• Not installed:
  • The app is unknown in the system and is not installed in the app's installation folder.
  • On app uninstallation the app install parts are deactivated in the system.

In addition, the app can have one running state:

• Started (RUN):
  • The installed app container file in the app's installation folder is mounted as read-only file system to a corresponding app folder in the started app's folder:
    /opt/plcnext/apps
  • All app start-parts from the app_info.json are already applied to the PLCnext Technology system and are "Online".
• Stopped (STOP):
  • Same as "Installed". The app container is not mounted and all app parts are not applied to the system ("Offline").
  • All app start-parts are deactivated and only the app install-parts are activated in the system.

A list of all apps installed on a controller can be viewed on the controller's web-based management. The WBM also shows the current state of all installed apps (as you can see in the topic "PLCnext Apps page" in the PLCnext Technology Info Center).