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Chapter 4 What You Need to Know about Moves
NI-Motion User Manual 4-6 ni.com
You can calculate this minimum velocity increment in RPM with the
following formula:
where Vmin = 1/65,536 counts/sample or steps/sample
Ts = sample period in seconds per sample
60 = number of seconds in a minute
R = counts or steps per revolution
or
You also can calculate the minimum velocity using the formula shown in
the Calculation Based on Units column in Table 4-1.
For a typical servo axis with 2,000 counts per revolution operating at a
250 µs update rate, the minimum RPM increment is
or
You can calculate the maximum velocity in RPM with the following
equation:
where Vmax = 20 MHz for servos
8 MHz for steppers on a NI 7350 controller
4 MHz for steppers on a NI 7330, NI 7340, or NI 7390
motion controller
R = counts/steps per revolution
minimum RPM Vmin
1
Ts
-----
× 60×
1
R
---
×=
minimum RPM MIN
1
R
---
×=
1
65,536
----------------
1
250 µs
----------------
× 60
1
2000
------------
×× 0.00183105 RPM=
3.662109
1
2000
------------
× 0.00183105 RPM=
maximum RPM Vmax 60×
1
R
---
×=