Tag Data Types

The following table lists all the data types available for Tags in Ignition.

Data Type	String Value	Integer Value
Byte	Int1	0
Short	Int2	1
Integer	Int4	2
Long	Int8	3
Float	Float4	4
Double	Float8	5
Boolean	Boolean	6
String	String	7
DateTime	DateTime	8
Text This feature was changed in Ignition version 8.1.8: The Text data type on tags was deprecated	Text	10
Byte Array	Int1Array	17
Short Array	Int2Array	18
Integer Array	Int4Array	11
Long Array	Int8Array	12
Float Array	Float4Array	19
Double Array	Float8Array	13
Boolean Array	BooleanArray	14
String Array	StringArray	15
DateTime Array	DateTimeArray	16
Binary Data	ByteArray	20
Dataset	DataSet	9
Document (JSON Document)	Document	29

Array and Dataset Data Types

The Array and Dataset data types available on Tags allow for multiple data points to be stored in a single Tag. Configuring a Tag as an array or dataset is as easy as changing the data type in the Tag Editor.

Array Tags

Many OPC servers and drivers already support array type Tags, and now each element in the array can easily be represented with the array data types in Ignition. Additionally, array data types can be used with devices that do not support array types, and will instead expose each bit in the value. Because the core data type of each element in the array is the same, it is possible to apply Tag History, Alarming, or Scaling configurations onto the array, and these configurations will be inherited by each element.

Array Tag Write-Back

OPC Array Tags support writing back to the device. How this is done can vary, depending on the type of OPC Server in use. Some OPC Servers support writes to individual array elements, where a write would occur just like any other Tag write. However, some OPC Servers do not support individual element writes, which means the whole array will need to be written back to the array Tag, even if only a single element is changing.

Dataset Tags

Dataset Tags allow multiple rows and columns worth of data to be stored in a Tag. Each column is exposed as a separate folder in the Tag (i.e., the "name" folder in the image below). Dataset Tags can be driven by a query, so it's possible to query for multiple columns on a row in a single Tag. This is more efficient than using multiple query Tags (and thus multiple queries) to retrieve the same data.

While dataset tags are convenient, note that the Tag History system and Alarm system do not support tags with dataset types.

Valid data types that can be stored in dataset tags include the following:

Float
Short
Long
Date
Integer
Boolean
String
Color
Double
Timestamp

Dataset Tag Example

The following example will create a dataset memory Tag and display the contents in a Table component.

Create a new Memory Tag. Name it Dataset, and change the data type to Dataset. The Dataset will be empty by default.
Click the Edit icon next to Value. The Value screen is displayed. For this example, we created a simple dataset with four columns and five rows.
Click the Add Column icon. Name the first column City and set type to be String.
Click Add Column.
Repeat adding columns as follows:

Column Name: Population Type: Integer
Column Name: TimeZone Type: String
Column Name: GMTOffset Type: Integer
Click the Add Row icon. Add the row information as follows:

New York 8368710 EST -5
Los Angeles 3833995 PST -8
Chicago 2853114 CST -6
Houston 2242193 CST -6
Phoenix 1567924 MST -7
Click the Commit button.
Click OK to save the Tag.

The Tag will now contain rows, columns, and values based on the configurations you made earlier in this example. Now you have a Tag with a dataset value that can be bound to by components in Vision and Perspective.

Document Type

The Document type allows a tag to have a JSON document as a value. Setting a Tag to this type will cause the value field to display an icon.

Clicking the icon will transition the Tag Editor into a JSON Editor, allowing you to manually write JSON directly to the value.

Click the + icon to add new members to the object. When finished, press Commit.

When saved, the value of the tag will render as a JSON document in the tag browser.

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