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Chapter 4 What You Need to Know about Moves
NI-Motion User Manual 4-8 ni.com
You can calculate the maximum velocity 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
and is constrained by acceleration/deceleration according to the following
equation:
velocity ≤ (65,536 × deceleration) – acceleration
where velocity is in counts/sample and acceleration and deceleration are in
counts/sample
2
.
NI 73xx Acceleration in Counts/s
2
Acceleration and deceleration values are converted to an internal
16.16 fixed-point format in units of counts/s
2
before being used by the
trajectory generator.
Table 4-2 shows the minimum and maximum acceleration update rates in
counts/sec
2
.
Table 4-2. Acceleration Update Rate in Counts/Sec
2
Update Rate MAX MIN
Calculation Based
on Units
62.5 µs 2,048,000,000 counts/sec
2
3906 counts/sec
2
Accel
max
= MAX
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
Accel
min
= MIN
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
maximum velocity Vmax=