How do I update initialization values of variables on the fly?

The first step in being able to update the initialization value your variables is to set the SAVE attribute in the Data Editor.

However, By itself, the SAVE feature does nothing, but this attribute is used along with the "Update Init values with Current Values" and "Update Local Init Values with PLC Init Values"

To better understand these features, you must first understand that there are 2 versions of the program on the PLC at any given time: The Stored Version, which is stored to Non-volatile Memory and the Running version of the project, which is loaded from Non-volatile Memory to the RAM when the PLC starts.

By having the SAVE attribute checked and launching "Update Init values with Current Values", which is equivalent to invoking %S94, this will update all the Initial values with the current values in the Running version of the project at the time the function is executed.

Then after "Update Init values with Current Values" is completed, you should trigger "Update Local Init Values with PLC Init Values" the same as triggering %S66 in order to update these values in the Stored version of the project.

If only "Update Init values with Current Values" is triggered without "Update Local Init Values with PLC Init Values" and the PLC is Power Cycled, then these init values will be lost, because the stored project was not updated.

These three features need to be used together in order to update initial values on the fly.

Released for: Schneider Electric Canada