Siemens SIMATIC S5 Manual page 129

Manual S5-115F
Unconditional block call "JU"
One block is called within another block, regardless of conditions.
In the case of jump operations to missing blocks, the operating system of the CPU 942-7UF12
responds differently depending on the operating mode.
• If a jump is called to a missing block in safety mode, the S5-115F stops.
• If a jump is called to a missing block in test mode, the jump is not executed and the program
processes the next operation. The S5-115F remains in RUN.
For this reason, construction of the complete user program step by step by successively loading
blocks is possible without continually rewriting OB 1. It is therefore possible to program OB 1
with all planned block calls.
Example: A special function has been programmed in FB 26. It is called at several locations in the
program, e.g. in PB 63, and processed.
Program Sequence
PB 63
JU FB 26
EWA 4NEB 811 6149-02
STL
.
.
FB 26
.
.
.
JU FB 26
.
STEP 5 Operations
Explanation
The "JU FB 26" statement in program
block PB 63 calls function block FB 26.
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