Reinitialisation and remanence

Hello SIOS forum community,

We keep getting questions about reinitialisation and remanence.

Reinitialisation means something like resetting.

There is a FAQ on this topic in the SIOS portal

How can you load modified data blocks into the S7-1200/S7-1500 without setting the CPU to STOP and without affecting the values of already loaded variables?

Explanation of loading without reinitialisation:

In order to subsequently change user programs that are already running in a controller, S7-1200 (from firmware V4.0) and S7-1500 controllers offer the possibility to extend the interfaces of optimised function or data blocks during operation. You can load the modified blocks without setting the control to STOP and without affecting the actual values of variables that have already been loaded.

For more information, see the Programming Guide (Chapter 3.2.8).

Or in the online help of the TIA Portal under

"Loading block extensions without reinitialisation".

Retentivity

The retentive data are permanently stored in the NVRAM (Non-Volatile Random-Access Memory) of the controller at zero voltage. Provided that there is no start-up obstacle and the programme is unchanged during the operating state transition of the CPU from start-up to RUN, the CPU will continue to operate with the retentive data. It is important to know that the programme is also considered changed if the same programme has been reloaded onto a memory card (change of checksum) and this card is then inserted into the CPU with voltage on. In such a case, the retentive data is initialised although it is not structurally changed. This means that it can happen that all setting values are lost on a machine even though retentivity is used.

For more information, see the programming guide (chapter 3.5).

Note

The procedure described in this article refers to the time of writing this article (status: April 2021).

Yours sincerely.

SIMATIC International Technical Support Hub