National Instruments NI-Motion, User Manual

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Chapter 4 What You Need to Know about Moves
NI-Motion User Manual 4-10 ni.com
You can calculate the minimum acceleration increment in RPS/s with the
following formula:
where Amin = 1/65,536 counts/sample
2
or steps/sample
2
Ts = sample period in seconds per sample
R = counts or steps per revolution
or
For a typical servo axis with 2,000 counts or steps per revolution operating
at the 250 µs update rate, calculate the minimum RPS/s increment using the
following equation:
or
Table 4-3. Acceleration Update Rate in RPS/s
Update Rate MAX MIN
Calculation Based
on Units
62.5 µs 2,048,000,000 counts/sec
2
3906 counts/sec
2
±RPS/s
max
= MAX×1/r
where r = counts/revolution
125 µs 2,048,000,000 counts/sec
2
977 counts/sec
2
187.5 µs 910,222,222 counts/sec
2
434 counts/sec
2
250 µs 512,000,000 counts/sec
2
244 counts/sec
2
312.5 µs 327,680,000 counts/sec
2
156 counts/sec
2
±RPS/s
min
= MIN×1/r
where r = counts/revolution
375 µs 227,555,556 counts/sec
2
109 counts/sec
2
437.5 µs 167,183,673 counts/sec
2
80 counts/sec
2
500 µs 128,000,000 counts/sec
2
61 counts/sec
2
RPS/s Amin
1
Ts
-----
 
 
2
×
1
R
---
 
 
×
=
RPM/s MIN
1
R
---
×
=
1
65,536
----------------
 
 
1
250
µ
s
---------------
 
 
2
1
2000
------------
× ×
0.122070 RPS/s
=
244
1
2000
------------
×
0.122
=