Load Circular Arc

Usage

status = flex_load_circular_arc(u8 boardID, u8 vectorSpace, u32 radius, f64 startAngle, f64 travelAngle, u8 inputVector);

Purpose

Loads parameters for making a circular arc move in a 2D or 3D vector space.

Tip  Refer to the Remarks section for information about how the behavior of this function differs between controllers.

Parameters

Parameter Discussion

vectorSpace is the vector space to control. Valid values are NIMC_VECTOR_SPACE1 through NIMC_VECTOR_SPACE15. On motion controllers that support fewer than thirty axes, configuring non-existent vector spaces returns error –70006 (NIMC_badResourceIDOrAxisError). Refer to Vector Spaces for vector space resource IDs.

radius is the arc radius in counts (servo axes) or steps (stepper axes).

startAngle is the double precision floating point value, in degrees, of the starting angle of the arc.

travelAngle is the double precision floating point value, in degrees, of the angle to traverse. A positive travelAngle defines counterclockwise rotation in the xy plane.

Note  Internally, the floating point values for startAngle and travelAngle are represented as scaled, fixed point numbers.

inputVector indicates the source of the data for this function. Available input vectors include immediate (0xFF), variable (0x01 through 0x78), or indirect variable (0x81 through 0xF8). Refer to Input and Return Vectors for more detailed information.

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.

Using This Function

This function defines an arc in the xy plane of a 2D or 3D vector space.

Note  Load the velocity and acceleration/deceleration before loading an arc.

The arc is specified by a radius, starting angle, and travel angle and like all vector space moves, uses the loaded values of vector acceleration and vector velocity to define the motion along the path of the arc. The following figure defines a circular arc:

Circular arcs are not limited to ±360°. Moves of over 4,000 circular revolutions in either direction can be started with one call to this function.

Refer to NI 73xx Arc Angles in Degrees for more information about representing angles numerically.

Remarks

This section includes information about how the behavior of this function differs among the controllers that support it.

NI 73xx Controller Considerations

The following list includes considerations you must make when you are using this function with a 73xx motion controller:

• The range for radius is 2 to 2³¹–1 counts (steps).
• The range for startAngle is 0 to 359.999313° where angle 0 is along the positive x axis and values increase counterclockwise from the positive x axis in the xy plane.
• The range for travelAngle is –1,474,560° to +1,474,200° (–4,096 to +4,095 revolutions).

NI SoftMotion Controller Considerations

The following list includes considerations you must make when you are using this function with the NI SoftMotion Controller:

• The range for radius is 0 to 2³¹–1 counts (steps).
• The range for startAngle is 0 to 360° where angle 0 is along the positive x axis and values increase counterclockwise from the positive x axis in the xy plane.
• The range for travelAngle is the full 64-bit range.