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Op-
tion
Name
Description
[3]
Speed
comp stop
Stops at precisely the same point, regardless of the present speed. The stop signal is delayed internally
when the present speed is lower than the maximum speed (set in
parameter 4-19 Max Output Frequency
).
The delay is calculated on the basis of the reference speed of the drive and not on the basis of the actual
speed. Make sure that the drive has ramped up before activating the speed–compensated stop.
[4]
Com cnt
stop w/rst
Same as
[3] Speed comp stop
but after each precise stop, the number of pulses counted during ramp down
to 0 RPM is reset.
[5]
Comp cnt
stop w/o r
Same as
[3] Speed comp stop
but the number of pulses counted during ramp down to 0 RPM is deducted
from the counter value entered in
parameter 1-84 Precise Stop Counter Value
. This reset function can be
used to compensate for the extra distance done during ramping down and to reduce the impacts of grad-
ual wear of mechanical parts.
The precise stop functions are advantageous in applications where high precision is required. If using a standard stop command,
the accuracy is determined by the internal task time. That is not the case when using the precise stop function. It eliminates the task
time dependence and increases the accuracy substantially. The drive tolerance is normally given by its task time. However, by using
its special precise stop function, the tolerance is independent of the task time because the stop signal immediately interrupts the
execution of the drive program. The precise stop function gives a highly reproducible delay from the stop signal is given until the
ramping down starts. Run a test to find this delay as it is a sum of sensor, PLC, drive, and mechanical parts.
To ensure optimum accuracy, there should be at least 10 cycles during ramping down, see:
Parameter 3-42 Ramp 1 Ramp Down Time
Parameter 3-52 Ramp 2 Ramp Down Time
Parameter 3-62 Ramp 3 Ramp down Time
Parameter 3-72 Ramp 4 Ramp Down Time
The precise stop function is set up here and enabled from DI at terminal 29 or terminal 33.
Parameter 1-84 Precise Stop Counter Value
Table 133: Parameter 1-84 Precise Stop Counter Value
1-84 Precise Stop Counter Value
Default value: 100000
Parameter type: Range, 0 - 999999999
Setup: All setups
Conversion index: 0
Data type: Uint32
Change during operation: True
Enter the counter value to be used in the integrated precise stop function,
parameter 1-83 Precise Stop Function
. The maximum per-
missible frequency at terminal 29 or 33 is 110 kHz.
N O T I C E
Not used for selections
[0] Precise ramp stop
and
[3] Speed comp stop
in
parameter 1-83 Precise Stop Function
.
Parameter 1-85 Precise Stop Speed Compensation Delay
Table 134: Parameter 1-85 Precise Stop Speed Compensation Delay
1-85 Precise Stop Speed Compensation Delay
Default value: 10 ms
Parameter type: Range, 0 - 100 ms
Setup: All setups
Conversion index: -3
Data type: Uint8
Change during operation: True
Enter the delay time for sensors, PLCs, and so on for use in
parameter 1-83 Precise Stop Function
. In speed–compensated stop mode,
the delay time at different frequencies has a major influence on the stop function.
AU373327181955en-000101 / 130R1208
88 | Danfoss A/S © 2021.08
Parameter Descriptions
VLT® AutomationDrive EZ FC 321
Programming Guide
