Saving and Compiling
S7-GRAPH for S7-300/400 Programming Sequential Control Systems
C79000-G7076-C526-01
8-9
8.5 Saving
Calculating Memory Requirements
With the following formulas, you can estimate how much space is required for an
S7-Graph FB and instance DB in the work memory (n - number of steps).
The following conditions apply:
•
The “Criteria analysis data in DB" option is not selected in the “Compile" tab
page.
•
Each step contains an average of 1.2 transitions, 1.5 actions and 0.8 time
monitoring functions.
•
Each transition contains an average of 3.5 conditions.
If significantly more conditions were programmed per transition, interlock or
supervision, the memory requirements can be considerably increased. 12 Bytes
are required per condition and action. Complex access, actions with
assignments or similar can also greatly increase the memory requirements.
FB = 4900 bytes + n * 130 bytes
DB = 270 b
tes + n * 70 b
tes
From this, it is clear that the maximum number of 250 steps is only theoretically
possible. To save space, you can, however, move the system functionality out to
one of the supplied (FC70, FC71, FC72).
Saving an S7-Graph FB or an S7-Graph Source File
The following options are available when you save an open object (block or source
file):
•
Select the menu command File > Save or click the "Save" button in the toolbar.
The object is saved under its present name.
•
If you require a copy of the current object, select the menu command File >
Save As. The "Save As" dialog appears which you can specify the object name
and path of the copy.
•
If you select the menu command File > Close, the Close button or the menu
command File > Exit and the modified object has not yet been saved, you will
be prompted to decide whether or not you want to save or discard the
modifications or cancel the Close command.
Note
If the sequencer still contains errors, it cannot be saved as an FB. As an
alternative, you can save it as an S7-Graph source file in which you can continue to
work. This allows you to eliminate the errors at a later point in time.
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