Statement List (STL) - DCE FEL ČVUT v Praze

6.16 JPZ Jump if Plus or Zero
Format
Description
Status word
Example
JPZ
Address Description
Symbolic name of jump destination.
Logic Control Instructions
If the result indicated by the status bits CC 1 and CC 0 is greater than or equal to
zero (CC 1=0/CC 0=0 or CC 1=1/CC 0=0), JPZ (jump if result >= 0)
interrupts the linear program scan and jumps to a jump destination. The linear
program scan resumes at the jump destination. The jump destination is specified by
a jump label. Both forward and backward jumps are possible. Jumps may be
executed only within a block, that is, the jump instruction and the jump destination
must lie within one and the same block. The jump destination must be unique within
this block. The maximum jump distance is -32768 or +32767 words of program code.
The actual maximum number of statements you can jump over depends on the mix
of the statements used in your program (one-, two-, or three word statements).
BR CC 1 CC 0 OV OS OR STA RLO /FC
writes: - - - - - - - -
STL Explanation
L IW8
L MW12
-I //Subtract contents of MW12 from contents of IW8.
JPZ REG0 //Jump if result >=0 (that is, contents of ACCU 1 >= 0).
AN M 4.0 //Program scan continues here if jump is not executed.
S M 4.0
JU NEXT
REG0: AN M 4.1 //Program scan resumes here after jump to jump label REG0.
S M 4.1
NEXT: NOP 0 //Program scan resumes here after jump to jump label NEXT.
Statement List (STL) for S7-300 and S7-400 Programming
A5E00706960-01 6-17