Changing the Data Source via Online Change
Important: Valid license at online change
To download data-source changes to a PLC via online change, a valid CODESYS Online Configuration Change license is required on the PLC device. Currently this feature can be used only on devices especially for this purpose.
If you change your application in the development system and then log in to the controller where this application is already running, then you will be offered an online change. This is also the case if you add, remove, or modify a data source in the application using a data source manager. During an online change, only the affected POUs are downloaded to or removed from the controller. The controller remains in online mode.
When data sources are changed online, the unchanged data sources are also affected by a certain downtime during which no variable values are exchanged. Nevertheless, these data sources do not lose their connections. Variables which are monitored from unaffected data sources do not switch to an error state.
For more information, see the following: Command: Online Change
Restrictions
If you make changes to the list of transferred variables or their assignments to local variables, then this will require you to download the application again.
Data source libraries provide some internal settings (for example, for rarely changed values such as the default reconnection time). A download is required to reliably apply such changes.