Data Backup and Initialization¶
Initialization of Variables, Overview
The initialization of variables to 0 or to the initialization value is performed by switching voltage ON, by a reset or after downloading the user program.
If internal variables shall be buffered, these variables have to be marked as “VAR_RETAIN” or “VAR_RETAIN PERSISTENT”. This applies to both the internal variables and the variables of the addressable flag area (%M area).
Note
Variables of the addressable flag area (%M area) for AC500-eCo CPUs PM55x and PM56x can not be buffered.
Note
- The order of the internal RETAIN variables is only kept when using the online change command. If the program is re-built, the order can change and, due to this, the buffered variables do no match.See also CoDeSys / Retentive variables, chapter “Behavior of RETAIN
- variables on download”: mainchapters/Remanentvariables
The following table shows an overview of the initialization values of the individual variables:
Note
For AC500-eCo CPUs, there is an 1 kByte VAR-RETAIN area and an 1 kByte %R area. Independently of an inserted battery, the memory values are stored in flash memory at power failures and are recovered when power returns. For the %R area, the values can be configured in Automation Builder under CPU Parameters.