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NI SMD-7613/7614/7615/7616 User Manual
The step smoothing process uses a command filter which causes a slight delay, or lag in the
motion. The following figure shows an example of the delay that can occur from using the step
smoothing filter.
Figure 40.
Delay Due to Filtering
Input Noise Filter
Electrical noise can negatively affect the STEP signal by causing the drive to interpret one
step pulse as two or more pulses. This results in extra motion and inaccurate motor and load
positioning. To solve this problem, the drive includes a digital noise filter on the STEP and
DIR inputs. The default factory setting of this filter is 7.5 MHz, which is suitable for most
applications.
Your maximum pulse rate equals the highest motor speed multiplied by the number of steps per
revolution. For example:
Consider the maximum pulse rate when deciding whether you must increase the filter frequency.
Rev/
S
ec
S
econd
s
0
2
6
8
4
–2
10
0.1
0.2
0.4
0.
3
0.5
0.7
0.8
0.6
0.9
12
0
–4
On
Off
Motion Profile with
S
tep
S
moothing Filter
40
revs
ond
sec
-------------------
20 000
steps
revs
----------------
,
×
800
kHz
=