Functions of the IM 151-7 CPU
8-23
ET 200S IM 151-7 CPU Interface Module
A5E00058783-04
8.4.4 Handling data in DBs
Recipes
A recipe is a collection of user data.
A simple recipe concept can be realized using non-process-related data blocks.
The recipes should have the same structure (length). There should be one DB for
each recipe.
Processing sequence of a recipe
The recipe is to be stored in the load memory:
The individual data records of the recipes are created as non-process-related
DBs using STEP 7 and downloaded to the IM 151-7 CPU. The recipes therefore
only occupy space in the load memory and not in the working memory.
Working with the recipe data:
Calling the SFC 83 ”READ_DBL” from the user program causes the data record
of the current recipe to be read out of the DB in the load memory and into a
process-related DB in the working memory. As a result, the working memory
only has to accommodate the data from one data record.
The user program can now access the data of the current recipe.
Load memory
(MMC)
Recipe 1
Recipe 2
:
Recipe n
Working memory
(IM 151-7 CPU)
Current
recipe
SFC 83
READ_DBL
SFC 84
WRIT_DBL
Figure 8-6 Handling recipe data
Writing back a modified recipe:
Calling the SFC 84 ”WRIT_DBL” from the user program writes new or modified
data records of a recipe, which are created during program processing, back to
the load memory.
The data written to the load memory is not erased by a memory reset and is
transferrable.
If modified data records (recipes) are to be stored on the PD/PC, they can be
uploaded and stored there as a complete block.
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