Positioning Down Ramp - Siemens SINAMICS G120 Operating Instructions Manual

Functions
5.10 Technological functions
5.10.4

Positioning down ramp

A basic positioning function in the inverter
In certain applications, e.g. when a conveyor belt is brought to a standstill, the belt may have
to travel a defined braking distance after it has been switched-off so that it always stops at
the same position.
For a fixed ramp-down type, the number of revolutions that a motor requires to reach a
standstill depends on the speed of the motor at the instant of the switch-off. Using the
"positioning down ramp" function, the number of revolutions from the OFF1 command down
to standstill can be defined independent of the speed.
The following diagram shows the principle signal characteristic of velocity (v) and position (s)
of a linearly moved load, e.g. of a conveyor belt, that is stopped using the positioning down
ramp. For a low velocity (v
at the same end position (s
1
2
0
Figure 5-15
The accuracy of this basic positioning function is adequate for many applications. The
accuracy is increased when using a speed encoder.
Table 5- 64
Parameters
P2480 = ...
P2481 = ...
P2482 = ...
P2484 = ...
P2488 = ...
P2487 = ...
For more information about this function, see the List Manual.
146
) the down ramp is extended so that the load comes to a standstill
2
) as for a higher velocity (v
0
2
1
Velocity (v) and position (s) of a linearly moved load with the positioning down ramp
Parameters for the simple positioning function
Description
Control command for the positioning function
Example: When P2840 = 722.0, the positioning function is activated via digital input
0.
Gear ratio = P2481/P2482
Number of shaft revolutions at the gearbox output for one distance unit
Number of distance units until the end position
Additive compensation value for increasing accuracy
).
1
CU240S and CU240E Control Units, FW 3.2
Operating Instructions, 03/2009, A5E02440075B AA