Technical data

Memory areas and retentive memory
2.2 Retentive memory areas
Structure and Use of the CPU Memory
Function Manual, 01/2013, A5E03461664-01
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2.2 Retentive memory areas
Introduction
The S7-1500 CPUs have memory available for storing retentive data at POWER-OFF.
Details about the size of the retentive memory can be found in the technical specifications for
the CPU.
In STEP 7, you can find the configured CPU's retentive memory utilization offline at
"Program information > Resources" or online at Online & Diagnostics under "Diagnostics >
Memory".
If you define data as retentive, its content is retained beyond program startup after STOP, or
a power failure.
You can define the following data and objects as retentive:
● Bit memories, timers and counters
● Tags from global data blocks
● Tags from instance data blocks of a function block
Certain tags of technology objects are always retentive, for example, adjustment values of
absolute encoders.
Bit memories, timers and counters
In STEP 7, you can define the number of retentive bit memories, timers and counters in the
PLC tag table using the "Retentive memory" button.
Figure 2-4 Definition of the number of retentive bit memories, timers and counters using the "Retentive memory" button