ETEL Doc. - Operation & Software Manual # DSC2P 903 / Ver. F / 3/6/05
Chapter C: System functions
Operation & Software Manual
Direct Drives & Systems
129
The
ACC
command (
ACC
eleration) defines the maximum acceleration a
max
during a movement.
The
SPD
command (
SP
ee
D
) defines the maximum speed v
max
for a movement.
The
POS
command (
POS
ition) has two functions: to define the position x
final
to reach during a movement and
to start the movement.
The
JRT
command (
J
e
R
k
T
ime) defines the jerk time value for S-curve movements. This value corresponds
to the extra number of times
a sti (166.67
µ
s for the DSC2P and DSC2V and 500
µ
s for the DSCDP, DSCDL
and DSCDM) that will take the S-Curve movement with respect to a trapezoidal movement at same speed,
same acceleration and same final position. The
JRT max value: Tmax = 500 x 166.67
µ
s = 83ms for the DSC2P
and DSC2V and 500 x 500
µ
s = 250ms for the DCSDP, DSCDL and DSCDM.
Here is the formula giving the jerk J, according to the acceleration A and the jerk time T (with ISO units):
Remark:
The jerk (J) is not always the same. If the movement reaches a constant speed, the above-
mentioned formula can be applied. However, if a constant speed is not reached, the following
formula must be used:
Example:
PWR.1=1
;Current is supplied in the phases (after a phasing, if it was the 1st PWR).
IND.1
;The motor moves up to the reference mark.
WTM.1
;Waits until the movement is finished
POS.1=0
;The motor moves exactly on the reference mark.
WTM.1
;Waits until the movement is finished
SET.1=100000
;’0 machine’ definition at 100000 [upi] of the reference mark position
MMD.1=1
;Selects S-curve movement.
ACC.1=500000
;Definition of a
max
.
SPD.1=200000
;Definition of v
max
.
JRT.1=200
;Definition of the jerk time: = 200x166.67
µ
s = 33,2 ms for the DSC2P/DSC2V and 200
x 500
µ
s = 100 ms for the DSCDP, DSCDL and DSCDM
Until now the motor is still positioned on the reference mark.
POS.1=300000
;The motor moves to position 300000 [upi] with a speed of 200000 [usi] and an
acceleration of 500000 [uai].
WTM.1
;Waits until the movement is finished
POS.1=10000
;The motor moves to position 10000 [upi] with the same speed and acceleration than
before.
WTM.1
;Waits until the movement is finished
POS.1=-15000
;The motor moves to an absolute negative position -15000 [upi] with the same speed
and acceleration than before.
WTM.1
;Waits until the movement is finished.
12.10.3.1Relative and absolute movements
The arithmetical oper, -, * and / are allowed with the POS, SPD, ACC and JRT commands. It is then
possible to realize not only absolute movements, such as the one described above, but also relative
movements using the arithmetical s and -.
POS.1=300000
Absolute movement
:
The motor moves to the absolute position 300000. The
movement can be positive or negative according to the
motor position with respect to the 300000 point.
J
m s
⁄
3
[
]
A m s
2
⁄
[
]
T s
[ ]
----------------------
=
A m s
2
⁄
[
]
T s
[ ]
----------------------
J
<
2
A m s
2
⁄
[
]
T s
[ ]
----------------------
⋅
≤
