Siemens S5-100U - Page 192

S5-100U STEP 5 Operations
Block End “BE”
The “BE” operation terminates a block. Data blocks do not need to be terminated. “BE” is always
the last statement in a block.
In structured programming, program scanning jumps back to the block where the call for the current
block was made.
Boolean logic operations cannot be continued in a higher-order block.
Example: Program block PB3 is terminated by the “BE” statement.
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BE
STL
The “BE” statement terminates
program block PB3 and causes
program scanning to return to
organization block OB1.
ExplanationProgram Sequence
BE
OB1 PB3
JU PB3
Unconditional Block End “BEU”
The “BEU” operation causes a return within a block. However, jump operations can bypass the
“BEU” operation in function blocks (see sections 8.2.10 and 8.3.4).
Binary logic operations cannot be continued in a higher-order block.
Example: Scanning of function block FB21 is terminated regardless of the RLO.
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JC=
BEU
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BE
The “BEU” statement causes program
scanning to leave function block FB21
and return to program block PB8.
STL ExplanationProgram Sequence
PB8 FB21
JC=
BEU
BE
JU FB21
EWA 4NEB 812 6120-02 8-37