Read Velocity in RPM

NI-Motion VI

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Read Velocity in RPM

Reads the filtered velocity of an axis or vector space in RPM.

Device Compatibility

Device	Compatibility
7330	Y
7340	Y
7344	Y
7350	Y
7390	Y
NI SoftMotion Controller for CANopen—Accelnet	Y
NI SoftMotion Controller for CANopen—Xenus	Y

Board ID is a unique number assigned by Measurement & Automation Explorer (MAX) used to send and receive commands and data to or from a specific NI motion controller.

Axis or Vector Space is the axis or vector space to read.

Retn Vect indicates the destination for the return data generated by this VI. Available return vectors include return data to the host (0xFF), to a variable (0x01 through 0x78), to an indirect variable (0x81 through 0xF8), and do not return data (0). Refer to Input and Return Vectors for more detailed information.

error in (no error) describes error conditions that occur before this VI runs. The default input of this cluster is no error. If an error already occurred, this VI returns the value of error in in error out. The VI runs normally only if no incoming error exists. Otherwise, the VI passes the error in value to error out. The error in cluster contains the following parameters:

	status is TRUE if an error occurred before this VI was called, or FALSE if not. If status is TRUE, code is a nonzero error code. If status is FALSE, code is zero or a warning code.
	code is a number identifying an error or warning. If status is TRUE, code is a nonzero error code. If status is FALSE, code is zero or a warning code. Use the error handler VIs to look up the meaning of this code and display the corresponding error message.
	source is a string that indicates the origin of the error, if any. Typically, source is the name of the VI in which the error occurred.

Filtered Velocity is the double precision floating point filtered velocity value in RPM. For vector spaces, RPM is the filtered vector velocity for the vector move. The sign of RPM indicates direction of motion.

Bd ID Out is provided for flow control. You can string together NI-Motion VIs by wiring the Bd ID Out terminal of one VI to the Board ID terminal of the next VI.

Resource Output is the Axis, Vector Space, ADC, or Encoder you wired into the VI. Use Resource Output to pass the resource to another VI and/or to display information about the device.

error out contains error information. If error in indicates an error, error out contains the same error information. Otherwise, it describes the error status that this VI produces.

	status is TRUE if an error occurred, or FALSE if not. If status is TRUE, code is a nonzero error code. If status is FALSE, code is zero or a warning code.
	code is a number identifying an error or warning. If status is TRUE, code is a nonzero error code. If status is FALSE, code is zero or a warning code. Use the error handler VIs to look up the meaning of this code and display the corresponding error message.
	source is a string that indicates the origin of the error, if any. Typically, source is the name of the VI in which the error occurred.

Using This VI

This VI returns the axis or vector space filtered velocity in RPM. The filtered velocity is measured based on time elapsed between position changes. To avoid quantization error and jitter in the mechanical system, a filtering algorithm in Load Velocity Filter Parameter is performed with parameters configured.

For vector spaces, this VI returns vector velocity, the root-mean-square of the filtered velocities of the individual axes that make up the vector space.

Note This VI requires previously loaded values of either counts per revolution (for servo axes) or steps per revolution (for stepper axes) to operate correctly.

Note Refer to VI Execution Times for benchmark timing information about your controller.

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