Chapter 4 What You Need to Know about Moves
NI-Motion User Manual 4-12 ni.com
Note If the distance of the move is too small, it may not be possible to reach the
commanded maximum move constraints. In such instances, NI-Motion adjusts the move
constraints lower to reach the commanded position.
NI 73xx Arc Angles in Degrees
The Load Circular Arc, Load Helical Arc, and Load Spherical Arc
functions take angle parameters in degrees as double-precision
floating-point values. These values are converted to an internal
16.16 fixed-point representation where the integer part corresponds to
multiples of 45° (for example, 360° is represented as 0x0008 0000).
Use the following formula to convert from floating-point to fixed point:
where Q = quotient, the integer multiple of 45°
R = remainder
For example, 94.7° is represented in 16.16 format as follows:
The minimum angular increment is
Note The conversion from floating-point to fixed-point is performed on the host
computer, not on the motion controller. To load arc functions from onboard variables,
you must use the 16.16 fixed-point representation for all angles.
Angle in degrees
45°
---------------------------------------- QR+=
Angle in 16.16 format Q.
·R
45°
-------- 65,536×
=
Angle in 16.16 format 2. 4.7°
45°
----------65,536×
0x0002.1ABD==
1
65.536
----------------
45°× 0.000687°=