Positioning Axes; What Is Positioning - Siemens SIMATIC S5 Manual

Positioning Axes

2.3 Positioning Axes

What is Positioning?

2.3.1
Positioning means approaching a previously specified point or previously specified coordinate
automatically following a procedure established by parameter assignment. Such an operation
can be controlled by either closed-loop or open-loop control systems.
Open-loop control
Fig, 2/3 Types of positioning
When using closed-loop control, the physical variable to be controlled is measured and com-
pared and matched to another value.
Once parameters can be assigned for the positioning opera?ion, a setpoint generator is neces-
sary, regardless of whether closed-loop or open-loop control is to be used. This setpoint gener-
ator supplies an output value, which depends both on the difference between the current
position of the axis and the required target point, as well as on the parameters, e.g. speed, accel-
eration or deceleration. The more opportunities for parameter assignment and for modifying par-
ameters during the positioning operation provided by the setpoint generator, the more complex
and comprehensive is its structure. In the simplest version, the output value of the setpoint gener-
ator is switched on and off. Specifying the maximum speed and maximum acceleration and
deceleration according to the mechanical capabilities of the plant improves the efficiency of the
operation.
Positioning control with the IP247 is open-loop.
The actual position of the drive is not monitored. The actual position specified by the IP247 is cal-
culated from the axis data and number of pulses output.
2-4
I
Positioning
Closed-loop control