BECKHOFF AX2000 CANopen communication profile - Manual (Page 102)

The figures show the difference between the set of setpoints mode and the single setpoint mode.
The initial status of the bit change_set_immediately in the control word determines which mode is
used. To keep these examples simple, only trapezoidal moves are used. If the bit
change_set_immediately is “0”(continuously drawn line in Figure 1) a single setpoint is expected by
the drive (1). After data is applied to the drive, a host signals that the data is valid by changing the
bit new_setpoint to “1" in the control word (2). The drive responds with setpoint_acknowledge set to
“1" in the status word (3) after it has recognized and buffered the new valid data. Now the host can
release new_setpoint (4) and subsequently the drive will signal through setpoint_acknowledge = “0"
its ability to accept new data again (5). In Figure 2 this mechanism results in a velocity of zero after
ramping down to reach a target_position X
1
at t
1
. After signaling to the host, that the setpoint has
been reached as described above, the next target_position is processed at t
2
and reached at t
3
.
With change_set_immediately set to “1" (6), symbolized by the dashed line in Figure 1, the host
instructs the drive to apply a new setpoint immediately after reaching the previous one. The relative
timing of the other signals is unchanged. This behavior causes the drive to process the next set-
point X
2
in advance, and to hold its velocity when it reaches the target_position X
1
at t
1
. The drive
then moves immediately to the next target_position X
2
that has already been calculated.
Bits im controlword:
Bit 4
new_set_point (positive Flanke!)
Bit 5 change_set_immediatly
Bit 6 absolut / relativ
Bits im statusword:
Bit 12 setpoint acknowledge
Bit 13 following error
102 CANopen for AX2000/2500
CANopen Drive Profile
07/2007
BECKHOFF
time
v
2
v
1
t
0
t
1
t
2
t
3
velocity
time
v
2
v
1
t
0
t
1
t
2
velocity