Working with variables in the data storage

Variables in the data storage are used to store values into the flash memory.

The value of a variable in the data storage is persisted as soon as it changes during a cycle. The value will be overwritten as soon as the value changes again, provided that the previous writing process is completed. The BUSY variable in the data storage monitors the writing process.

ATTENTION

Writing to variables in the data storage degrades the memory. Make sure that the value of a variable in the data storage does not change too often.

If the real-time application is stopped or after a restart of the controller, the real-time application starts with the last stored value.

Since the variable is stored in the flash memory of the controller, it can be accessed across different applications. If you create a variable of the same name and data type in a second application, the second application will start with the previously stored value of the variable in the flash memory. If you do not use a variable of the same name and data type in a second application, the existing variable in the flash memory will be deleted as soon as the second application is deployed.

The storing process takes a few milliseconds. Do not power cycle the controller during the storing process. Otherwise values may be lost.

1. Use the BUSY variable to monitor the storing process.