Siemens S7-1500 Function Manual page 29
Automation system
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- System manual (523 pages) ,
- Function manual (402 pages) ,
- Manual (188 pages)
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Memory areas and retentive memory
2.3 Retentive memory areas
Creation of a data block in the user program
The instruction "CREATE_DB" is used to create a new data block in the load and/or work
memory. For data blocks which you create in the load memory, depending on the selection
for the ATTRIB parameter, the generated data block either has the property "retentive" or the
property "non-retentive". Setting the retentivity for individual tags is not possible here. The
"Optimized block access" attribute is disabled.
You can find additional information on the "CREATE_DB" instruction in the STEP 7 online
help under "Programming a PLC > Instructions > Extended instructions > Data block control
> CREATE_DB: Create data block".
Note
Redundant S7-1500R/H system
The "CREATE_DB" instruction is not supported by the CPUs of the redundant system S7-
1500R/H.
Tags of technology objects
Tags of technology objects are retentive, e.g. calibration values of absolute encoders.
STEP 7 manages the retentivity of the technology object tags automatically. Hence, you do
not have to configure retentivity.
The retentive tags of technology objects are unaffected by a memory reset. They can be
deleted only by a reset to factory settings.
Note
Redundant S7-1500R/H system
Technology objects are not supported by the CPUs of the redundant system S7-1500R/H.
28
Structure and Use of the CPU Memory
Function Manual, 10/2018, A5E03461664-AC
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