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Read LCD (G Dataflow)

Last Modified: June 25, 2019

Reads an LCD display in an input image using the descriptor of the ROI calculated by Get LCD ROI.

Read LCD returns the number as a double and as a string. The segment status output indicates if the number is recognized correctly or if any of the digits are not recognized fully. This output returns the status of each of the digits in the display. This node reads LCD or LED indicators and tolerates light drift.

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LCD/LED?

Boolean that controls the indicator type.

TRUE LED indicator
FALSE LCD indicator

Default: FALSE

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image in

Reference to the source image.

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ROI descriptor

Descriptor that defines the region of interest that contains the quadrilaterals surrounding each digit.

The ROI is calculated by the Get LCD ROI node.

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Global Rectangle

Coordinates of the bounding rectangle.

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Contours

Individual shapes that define an ROI.

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ID

Object specifying if contour is the external or internal edge of an ROI.

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Type

Shape type of the contour.

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Coordinates

Relative position of the contour.

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threshold

Threshold that determines whether a segment is on or off.

A segment is considered on if the standard deviation of the pixels along a line profile across the segment is greater than this threshold. Increase this value when using images with high contrast. Lower this value when using images with low contrast.

Default: 8

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search sign

Boolean that indicates if the algorithm reads the sign of the indicator.

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error in

Error conditions that occur before this node runs.

The node responds to this input according to standard error behavior.

Standard Error Behavior

Many nodes provide an error in input and an error out output so that the node can respond to and communicate errors that occur while code is running. The value of error in specifies whether an error occurred before the node runs. Most nodes respond to values of error in in a standard, predictable way.

error in does not contain an error error in contains an error
If no error occurred before the node runs, the node begins execution normally.

If no error occurs while the node runs, it returns no error. If an error does occur while the node runs, it returns that error information as error out.

If an error occurred before the node runs, the node does not execute. Instead, it returns the error in value as error out.

Default: No error

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search decimal separator

Boolean that specifies if a decimal separator exists after each digit.

Default: FALSE

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string

Number read from the display.

If the decimal separator is on and the control search decimal separator is TRUE, it is represented in the string by a dot (.) symbol.

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value

Value of the number represented by the display.

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segments status

Array of clusters containing the state of the segments of each digit.

The order of the cluster is illustrated below.

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error out

Error information.

The node produces this output according to standard error behavior.

Standard Error Behavior

Many nodes provide an error in input and an error out output so that the node can respond to and communicate errors that occur while code is running. The value of error in specifies whether an error occurred before the node runs. Most nodes respond to values of error in in a standard, predictable way.

error in does not contain an error error in contains an error
If no error occurred before the node runs, the node begins execution normally.

If no error occurs while the node runs, it returns no error. If an error does occur while the node runs, it returns that error information as error out.

If an error occurred before the node runs, the node does not execute. Instead, it returns the error in value as error out.

Where This Node Can Run:

Desktop OS: Windows

FPGA: Not supported

Web Server: Not supported in VIs that run in a web application


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