Siemens S7-1200 Programming Manualline page 34

3 General Programming
3.2 Program blocks
Figure 3-9: Multi-instances
FB
Switch-on
delay call
Advantages
Reusability
Multiple calls are possible
Clearer program with fewer instance DBs
Simple copying of programs
Good options for structuring during programming
Properties
Multi-instances are memory areas within instance DBs.
Recommendation
Use multi-instances in order to ...
reduce the number of instance DBs.
create reusable and clear user programs.
program local functions e.g. timer, counter, edge detection.
Example
If you require the time and counter function, use the "IEC Timer" blocks and the
"IEC Counter" blocks instead of the absolutely addressed SIMATIC Timer. If
possible, also always use multi-instances here. This keeps the number of blocks in
the user program low.
Programming Guideline for S7-1200/1500
V1.2, Entry ID: 81318674
Multi-instance DB
FB Parameter
FB Statics
TOF_TIME
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