Siemens SIMATIC S5-100U System Manual page 192

STEP 5 Operations
Unconditional Block Call "JU"
One block is called within another block, regardless of conditions.
Example: A special function has been programmed in FB26. It is called at several locations in
the program, e.g., in PB63, and processed.
Program Sequence
PB63
JU FB26
Conditional Block Call "JC"
One block is called within another block when the previous condition has been satisfied
(RLO = "1").
Example: A special function has been programmed in FB63. It is called and processed under
certain conditions, e.g., in PB10.
Program Sequence
PB10
A I 0.0
JC FB63
8-34
STL
.
FB26
.
.
.
.
JU FB 26
.
STL
.
FB63
.
.
S F
A I
JC FB 63
.
Explanation
The "JU FB26" statement in program
block PB63 calls function block FB26.
Explanation
The "JC FB63" statement in program
block PB10 calls function block FB63
if input I 0.0 is "1".
1.0
0.0
S5-100U
EWA 4NEB 812 6120-02b