94 Program features
Limit to limit control
The Limit to limit control function restricts the forward and reverse movement of a
load inside two extreme points. The function supports the monitoring of two sensors
at both ends of the movement range: one for the slow down point and the other for
the stop point. The system installer must install the sensors (eg, limit switches) and
connect them to the drive.
In the forward direction, the function allows normal operation of the drive until the
movement reaches the forward limiting points:
- When the drive receives the forward slow down signal, it decelerates the speed
to the slow down speed. Slow down speed allows smooth transition to stop at a
later stage. Vector mode uses the Speed reference ramp (
23.11
...
23.15
) and
Scalar mode the Freq reference ramp (
28.71
...
28.75
).
- When the drive receives the forward stop signal, it stops the motor. It uses the
drive stop mode selection (
21.03
). The function allows start only in the reverse
direction.
In the reverse direction, the function monitors reverse slow down and reverse stop
signals. The operation is similar as in the forward direction.
You can enable the function by a parameter, and define the signal sources for the
forward slow down, forward stop, reverse slow down and reverse stop. You can also
define the slow down speed by a parameter.
The Limit to limit function detects the signal status changes only when the function is
active, and the load is moved by the drive and motor. The function does not update
the signal states in its state machine despite of the actual status changes:
1. when the user has deactivated or disabled the function
2. when the function has stopped the motor but the load is moved by a force other
than the drive and motor (e.g., by a gravity).
For application example, see sections
Crane stop limit function
on page
546
,
Crane
slowdown function
on page
548
, and
Fast stop
on page
550
.
ACS380 FW.book Page 94 Friday, May 4, 2018 4:18 PM
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