Statement List (STL) - DCE FEL ČVUT v Praze

Logic Control Instructions
6.11 JOS Jump if OS = 1
Format
Description
Status word
Example
JOS
Address Description
Symbolic name of jump destination.
If status bit OS is 1, JOS 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: - - - - 0 - - - -
STL Explanation
L IW10
L MW12
*I
L DBW25
+I
L MW14
-I
JOS OVER //Jump if overflow in one of the three instructions during
calculation OS=1. (See Note).
T MW16 //Program scan continues here if jump is not executed.
A M 4.0
R M 4.0
JU NEXT
OVER: AN M 4.0 //Program scan resumes here after jump to jump label OVER.
S M 4.0
NEXT: NOP 0 //Program scan resumes here after jump to jump label NEXT.
Note
In this case do not use the JO instruction. The JO instruction would only check the
previous -I instruction if an overflow occurred.
Statement List (STL) for S7-300 and S7-400 Programming
6-12 A5E00706960-01