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Read Tag History (I32) (G Dataflow)

Last Modified: February 18, 2020

Returns the historical values from a single tag. The data type of the tag must be a 32-bit integer.

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tag in

Reference to a tag on the server.

Use Open Tag or Query Tags to obtain this reference.

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window

Time range you specify to read historical tag values.

The default is set to read all values decimated to 1,000.

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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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next window

Next page of historical tag data, if available.

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tag out

Reference to a specific tag on SystemLink Server or SystemLink Cloud.

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values

Data value of the tag or tags.

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time stamps

Dates and times the server obtained the most recent historical data values.

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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.
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end of data?

Boolean that indicates whether the node read the last of the data for the tag.

Where This Node Can Run:

Desktop OS: Windows

FPGA: Not supported

Web Server: Supported in VIs that run in a web application


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