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S5-95F
7.3.2
Program Blocks (PBs)
Self-contained program parts are programmed in program blocks.
Special feature : Control functions can be represented graphically in program blocks.
Call
Block calls JU and JC activate program blocks. You can program these operations in all block types
except data blocks. Block call and block end cause the RLO to be reloaded. However, the RLO can
be included in the "new" block and be evaluated there.
7.3.3
Sequence Blocks (SBs)
Sequence blocks are special program blocks that process sequence controls. They are treated like
program blocks. You can use sequence blocks in the control program, but you can also use them
like program blocks.
7.3.4
Function Blocks (FBs)
Frequently recurring or complex control functions are programmed in function blocks.
Function blocks have the following special features.
•
FBs can be assigned parameters.
Actual parameters can be assigned when the block is called.
•
FBs have an extended set of operations not available to other blocks.
•
The FB program can be written and documented in STL only.
Function blocks can be divided into the following types:
•
FBs that you can program
•
FBs that are integrated in the operating system (see section 9.2)
•
FBs that are available as software packages (Standard Function Blocks, see Catalog ST 57)
Standard function blocks for the S5-95F are specially protected and can neither be read nor
changed. Blocks without a prototype test cannot be executed in the S5-95F.
EWA 4NEB 812 6210-02
Introduction to STEP 5
7-11
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