Siemens SIMATIC S5 Manual page 316

STEP 5 Programming
START
Evaluate auxiliary
and edge flags
Edge flag = 0?
no
Load bit 1 = 1
(QB 65) into FY 6
END
9-28
FB 22 - NAME:STOP
Programming the auxiliary and edge flags for the
STOP function
Program auxiliary and edge flags
A I
AN F
= F
A I
= F
yes
Edge flag not yet set abort
AN F
BEC
Load Start command
L KB 2
T FY 6
BE
3.2 STOP KEY
4.2
4.3 EDGE FLAG
3.2 STOP KEY
4.2
4.3
STOP COMMAND
EWA 4NEB 812 6057-02
IP 266