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Chapter 4 What You Need to Know about Moves
© National Instruments Corporation 4-9 NI-Motion User Manual
You can calculate the minimum acceleration increment with the following
formula:
where Amin = 1/65,536 counts/sample
2
or steps/sample
2
Ts = sample period in seconds per sample
For a typical servo axis with 2,000 counts per revolution operating at the
250 µs update rate, calculate the minimum acceleration/deceleration
increment using the following equation:
You can calculate the maximum acceleration/deceleration using the
following equation:
where Amax = 32 counts/sample
2
Ts = sample period in seconds per sample
and is constrained according to the following equations:
acceleration ≤ 256 × deceleration
deceleration ≤ 65536 × acceleration
NI 73xx Acceleration in RPS/s
Acceleration and deceleration values in RPS/s are converted to an internal
16.16 fixed-point format in units of counts/sample
2
or steps/sample
2
before
being used by the trajectory generator.
Table 4-3 shows the minimum and maximum acceleration update rates in
counts/sec
2
.
minimum acceleration/deceleration Amin
1
Ts
-----
2
×=
1
65536
---------------
1
250µs
---------------
2
× 244 counts/second
2
=
maximum acceleration/deceleration Amax
1
Ts
-----
2
×=