Siemens SIMATIC S5 Manual page 321

IP 266
9.5 Sample Program 2: Traversing to Two Fixed Target
Positions
A second sample program is to be written to move the drive from one fixed
target position to another in "Relative increment" mode. At each of the two
fixed target positions, the direction of travel is to be reversed and a new
positioning operation started.
• Example
Flags Is used as
M 3.0 Edge flag
Flag bit 3.0 must be set to start a positioning operation. This bit ensures that a
mode can be started only when the Job Terminated bit has been set for this
operation.
To start the first operation, the bit must be set "externally", e.g. via an input.
You must scan this input in OB 1.
You can take basic functions, such as the wait loop for the IP runup and mode 99
for synchronizing the IP 266, from sample program 1. This means that you can use
OB 22, FB 27, OB 1 and FB 10.
In OB 1, FB 11 must be invoked in place of FB 26.
The description of FB 11 includes only the automatic sequence controlled by this
function block.
EWA 4NEB 812 6057-02
STEP 5 Programming
9-33