Technical data

Glossary
Structure and Use of the CPU Memory
36 Function Manual, 01/2013, A5E03461664-01
Optimized block access
Data blocks with optimized access have a no fixed defined structure. In the declaration, the
data elements only receive a symbolic name, and no fixed address within the block. The
elements are automatically so arranged in the block's available memory area, that its
capacity is optimally exploited.
In these data blocks, you can only address tags symbolically. For example, you would
access the "FillState" tag in the "Data" DB as follows:
"Data".FillState
Optimized access offers the following advantages:
● The data is structured and saved in a manner that is optimal for the CPU used. This
allows you to increase CPU performance.
● Access errors, from HMI, for example, are not possible.
● You can selectively define individual tags as retentive.
Process images (I/O)
The CPU transfers the values from the input and output modules in this memory area. At the
start of the cyclic program the signal states of the input modules are transmitted to the
process image of the inputs. At the end of the cyclic program the process image of the
outputs is transmitted as signal state to the output modules.
Reset to factory setting
Resetting to factory settings restores the CPU settings to the delivery state.
Restart
Restart occurs at the transitions from STOP to STARTUP, and POWER ON to STARTUP.
Before processing the cyclic program processing, the CPU first processes the startup OB or
OBs.
Restart has the following effects on the memory areas of the CPU:
● The process images are deleted.
● The retentive tags of data blocks retain the values saved in retentive memory.
● All retentive bit memories, timers, and counters retain the values saved in retentive
memory.
● All non-retentive user data is initialized:
– Data blocks receive their start value
– Bit memories, timers, and counters with "0"
SIMATIC memory card
Memory for the user program for programmable modules and communication processors.
You can also use the SIMATIC memory card for changing user software and user data.