Infinite Rotary Movements - Etel DSC Series Operation & Software Manual

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13.3.3 Infinite rotary movements

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A rotary motor can make an infinite rotation in one or the other direction if there is no mechanical end stop to
limit its stroke. This type of movement is selected with the MMD command. To avoid the motor real position
value to become too important and exceed the controller's position counter limit, it must be reset at regular
intervals via the parameter K27.
The motor turns indefinitely in the way defined by parameter K209. Its position is always included between 0
and parameter K27.
13.3.3.1 Functioning principle
Supposing that a rotary motor revolves at constant speed, the measure of the position versus time is:
Position [increment]
120000
80000
40000
The position measure increases continuously and after a lapse of time it will be so big that the controller will
not be able to handle it. To avoid it, as soon as the motor reaches the position programmed with parameter
K27, the position is brought back to 0. Thus, the motor position is never bigger than parameter K27. If the value
20000 is inserted in parameter K27 (1/2 a turn), the motor position measure versus time would likely be:
K27=20000
The movement undertaken before the distance measured has been reset is called a cycle. In the case above,
a cycle corresponds to half a turn. The size of a cycle definition depends on the application.
Remark: In infinite rotary mode (MMD = 24), the acceleration can be modified only when the speed is
constant (and whatever the value of MMC).
Infinite rotary movement example:
K209.1=0
MMD.1=24
K27.1=20000
ACC.1=300000
SPD.1=200000
POS.1=1
Remark: K209 = 0 would give a positive movement, and K209 = 1 would give a negative movement (refer
to §12.10.4.1)
Chapter C: System functions
Operation & Software Manual
Direct Drives & Systems
DSC2P
rd
3 turn
nd
2 turn
st
1 turn
0
Normal rotary movement
Position [increment]
0
Infinite rotary movement
Selects a positive movement
Selects an infinite rotary movement
Defines parameter K27
Defines the movement acceleration
Defines the movement speed
Starts an infinite movement whatever the value of the POS.1
DSC2V DSCDP
30000
time
20000 => 0
10000
time
20000 => 0
ETEL Doc. - Operation & Software Manual # DSC2P 903 / Ver. F / 3/6/05
DSCDL
0 (initial position)
10000
20000
(initial position)
10000
DSCDM