Operation & Software Manual
154
Direct Drives & Systems
Chapter C: System functions
ETEL Doc. - Operation & Software Manual # DSC2P 903 / Ver. F / 3/6/05
13.3.3 Infinite rotary movements
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:
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:
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
Selects a positive movement
MMD.1=24
Selects an infinite rotary movement
K27.1=20000
Defines parameter K27
ACC.1=300000
Defines the movement acceleration
SPD.1=200000
Defines the movement speed
POS.1=1
Starts an infinite movement
whatever the value of the POS.1
Remark:
K209 = 0 would give a positive movement, and K209 = 1 would give a negative movement (refer
to
)
Available on
DSC2P
DSC2V
DSCDP
DSCDL
DSCDM
0
120000
80000
40000
10000
20000
30000
0
Position [increment]
time
(initial position)
3
rd
turn
2
nd
turn
1
st
turn
Normal rotary movement
Position [increment]
(initial position)
time
K27=20000
0
10000
10000
20000 => 0
20000 => 0
Infinite rotary movement
