Read Encoder Data

NI-Motion VI

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Read Encoder Data

Reads position status or data from the selected encoder.

Device Compatibility

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

attribute is the attribute you want to read. The following are valid attributes:

position—Returns the quadrature count value of the encoder mapped to the selected axis to the double element of the data cluster.
index position—Returns the captured index position after a Find Index search to the double element of the data cluster.
index capture occurred—Returns the status to the Boolean element of the data cluster. True (On) indicates that the encoder index position capture occurred. False (Off) indicates that the encoder index position was not captured.

board in is a unique number assigned by Measurement & Automation Explorer used to send and receive commands and data to or from a specific NI motion controller.

axis in is the axis to read with this VI.

index in is the encoder index value. Valid value is 1 for the primary encoder.

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.

data is a cluster of variables that contains the values for the selected attribute. Read the correct element of the cluster for the attribute. The values of the other elements in the cluster are undefined.

	integer is 32-bit integer data.
	double is 64-bit floating point data.
	Boolean is Boolean data.

board out is provided for flow control. You can string together NI-Motion VIs by wiring the board out terminal of one VI to the board in terminal of the next VI.

axis out is provided for flow control. You can string together NI-Motion VIs by wiring the axis out terminal of one VI to the axis in terminal of the next VI.

index out is provided for flow control. You can string together NI-Motion VIs by wiring the index out terminal of one VI to the index in terminal of the next VI.

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

Use this VI to read status or data from the selected encoder.

Caution If this VI uses reflective memory, it should not be used for event checking. In this case, only use the information returned by this VI for display purposes. Refer to Reflective Memory VIs for more information.

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

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