A boot application is the application version, which is started automatically when the controller is switched on or started. For this to happen, the application on the PLC has to exist as a ‎<application name>.app‎ file.

For each application that is running on the PLC, a boot application can also be saved there.

By default, CODESYS generates the boot application automatically when an application is downloaded and transfers them to the PLC. The default settings for automatic generation are located in the “Properties” of the application object in the “Boot application”category. When logging in with a changed application, you are still prompted whether or not to generate a new boot application.

In addition, you can click “Online  Create Boot Application” at any time in online mode to create a new boot application.

You can create and save a local copy of a boot application in offline mode as well. Then, you can copy this application to the PLC with external tools. As a result, you can transfer an application to the PLC, even when there is no connection to CODESYS.