Danfoss VLT Series Programming Manual page 62

Servo Drive Operation
between logical and absolute rotor angle is established or
re-established. This is useful, if the axis has to be moved to
2 2 an absolute position after a loss of the reference position
by using a variable movement (for example, MoveDistance-
Segment).
Usually the ReturnSegment is used at the beginning of the
CAM to start from a defined absolute position. The Return-
Segment is used in conjunction with devices which have
multiple, equidistant, and equivalent starting positions, for
example, a square device.
The axis automatically selects the shortest way and
calculates a polynomial of 5
valid position. A backward movement of the servo drive is
possible. Valid positions are calculated by the formula:
partition
+ o setRev
revolutions
The ReturnSegment should be the first segment in a CAM
profile. It provides a means to return to the next
equivalent starting position and eliminate all rounding
errors. This segment must always start in standstill and it
also stops in standstill.
startPos
precNode
Illustration 2.91 Return Segment
Partitio 0
n
Possibl
e
shapes
valid
each
phys.
rotor
angles
worst 0°
case
angle
to turn
Table 2.23 Partition Example of ReturnSegment for
Single-turn Axis (revolutions = 1; offsetRev = 0)
60
VLT
th
degree to reach the next
depends on the
position at the start
of the segment and
the parameters
succNode
1 2 3 4 5
0° 0° 0° 0° 0°
180° 120° 90° 72°
240° 180° 144°
270° 216°
288°
±180° ±90° ±60° ±45° ±36°
Danfoss A/S © 01/2017 All rights reserved.
®
Integrated Servo Drive ISD
Illustration 2.92 Start/Endpoint Representation
Attribute
segID
precNode
succNode
startPos
partition
revolutions O; default = 1
End position
offsetRev
Guide
value
6 ...
0°
60°
startAction Same as in Table 2.17.
120
endAction Same as in Table 2.17.
180°
240° Table 2.24 Attributes for ReturnSegment in Start/Endpoint
Representation
300°
±30°
Coefficient representation: This representation is not
available.
EventSegmentContainer:
The EventSegmentContainer embeds a time-related
movement (composed by EventNodes and EventSegments)
into the guide value-related process. It provides a certain
®
510 System
Mandatory/ Value Description
optional range/
(+default allowed
value) values
Same as in Table 2.17.
Same as in Table 2.17.
Same as in Table 2.17.
O Float See Table 2.18 for type=
relative.
O; default = 0 Integer: Can be used for shaped
(0;16) plates when several
equal, valid starting
positions are allowed.
The worst case
movement is
influenced by this
parameter.
Integer >0 Number of revolutions
that are used when
calculating valid
positions, for example,
if there is a gear.
O; default = 0 Float Desired end rotor
position relative to the
nearest physical
position. The reference-
position is determined
by the absolute
position at the
beginning of this
segment and the
partition/revolutions.
Given in revolutions of
the axis.
MG36D102