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/sample² or steps/sample² before being used by the trajectory generator.

The following table shows the minimum and maximum acceleration update rates in counts/sec².

Update Rate	MAX	MIN	Calculation Based on Units
62.5 µs	2,048,000,000 counts/sec2	3906 counts/sec2	±RPS/smax = MAX×1/r where r = counts/revolution
125 µs	2,048,000,000 counts/sec2	977 counts/sec2
187.5 µs	910,222,222 counts/sec2	434 counts/sec2
250 µs	512,000,000 counts/sec2	244 counts/sec2
312.5 µs	327,680,000 counts/sec2	156 counts/sec2	±RPS/smin = MIN×1/r where r = counts/revolution
375 µs	227,555,556 counts/sec2	109 counts/sec2
437.5 µs	167,183,673 counts/sec2	80 counts/sec2
500 µs	128,000,000 counts/sec2	61 counts/sec2

You can calculate the minimum acceleration increment in RPS/s with the following formula:

RPS/sec = Amin × ()² ×

where

Amin = 1/65,536 counts/sample² or steps/sample²

Ts = sample period in seconds per sample

R = counts or steps per revolution

or

RPM/s = MIN ×

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:

() × ()² × = 0.122070 RPS/s

or

244 × = 0.122

You can calculate the maximum RPS/s using the following equation:

maximum RPS/s = Amax × ( )² × ()

where

Amax = 32 counts/sample²

Ts = sample period in seconds per sample

R = counts or steps per revolution

and is constrained according to the following equations:

acceleration 256 × deceleration

deceleration 65536 × acceleration

or

For a typical servo axis with 2,000 counts or steps per revolution operating at the 250 µs update rate, calculate the maximum RPS/s increment using the following equation:

32 × ()² × = 256,000 RPS/s

RPS/s values stored in onboard variables are in double-precision IEEE format (f64).