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 Encoder is the axis or encoder 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.
	Encoder Position is the encoder position is quadrature counts.
	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

The Read Encoder Position VI returns the quadrature count value of the encoder selected. The encoder must be enabled, either directly through the Enable Encoders VI or automatically, by being mapped to an enabled axis.

The Read Encoder Position VI is typically used to read the value of an encoder that is not part of an axis. This encoder could be a master encoder used for master-slave gearing or an independent position or velocity sensor.

For reading encoders mapped to axes, you can call this VI on the axis or directly on its mapped encoder. For servo axes, both approaches return the same value as the Read Position VI. On stepper axes however, this VI can return additional useful information.

During axis set up, you can operate the closed-loop stepper axis in open-loop mode and use this VI to directly measure the counts per revolution and steps per revolution for the axis. These values must be loaded in advance for subsequent closed-loop operation. Refer to the Load Counts/Steps per Revolution VI for more information.

You also can use this VI to return a finer reading of position in cases where the encoder resolution greatly exceeds the step resolution of the closed-loop stepper axis.