BECKHOFF AX2000 CANopen communication profile - Manual (Page 61)

Example: The speed-setpoint provision is to be made in revolutions per minute (revs/min).
The transmission ratio and feed constant are 1.
velocity_ encoder_ factor
2
1
1
1
1
incr
s
20
=
Expanded for revs/min:
velocity_ encoder_ factor
2
1
1
1
1
[m]
[ ]
incr
s
1
60[
20
m
s
s
m
= ´
in
20
]
2
60
incr
s
=
Þ Numerator : 2
20
Divisor : 60
Þ
Setpoint provision in [revs/min] for Object 60FF
h
target_velocity / velocity units
Þ
Setpoint provision in [incr/s] for Object 6081
h
Profile_velocity / speed units
Note: Since the speed controller operates internally with a resolution of 2
20
bits/turn,
regardless of the resolution of the encoder system, the following expression is
used to calculate the operating mode pv (for revolutions per minute):
increments
262144
1875
speed setpoint[min ] 1 = ´ -
This incremental setpoint provision should be used for cyclical applications (for example, position
control, 4ms cycle). The advantages are: no rounding error, lower CPU loading.
The above calculation is valid if divisor or numerator is set to 0.
The velocity_encoder_factor also affects Object 6081
h
profile_velocity. In order to be able to use
this factor for the position mode (pp) as well, the internal gearing factors PGEARI and PGEARO
must be equal (PGEARI =PGEARO; Object 2020
h
Sub-index: 08
h
,09
h
). If the divisor or numerator
is set to 0, then the internal scaling is used: increments per cycle (250 µs).
CANopen for AX2000/2500 61
BECKHOFF
07/2007
CANopen Drive Profile