Siemens SIMATIC S5 Manual page 166

Testing and Simulation with COM 265
Isolate parts of the control system flowchart (<F3> "Isolate")
Parts of the control system flowchart, all the way down to individual COM 265 language elements,
can be isolated for simulation. Isolating points can serve a practical purpose when specific parts of
the IP 265 user program (e.g. those containing errors) are not to affect other portions of the
program.
In a control system flowchart, COM 265 inserts lower-case letters at the designated isolating points;
these letters are then used to address the points.
Isolating points may be generated between language elements in all binary connecting lines. The
connections (circuitry) are "cut" only in a "symbolic" or "graphic" sense.
Note
Isolating points may not be inserted in front of connectors or in connecting lines which
lead to the control system flowchart's output bar.
The simulator treats the isolating point like an IP 265 input to which it can apply signal state "0" or
"1" for the next program segment.
Note
Isolating points can be affected interactively by pressing the associated letter key.
10-8
IP 265
EWA 4NEB 812 6130-02a