Tag Data Types

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

Datatype	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	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	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.

Array Tag Write-Back

OPC Array Tags now 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.

Array Alarm Example

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.

For this example, create the Tag WriteableInteger1.
In the Tag Browser, right click on the WriteableInteger1 Tag and choose Copy.
Right click on the Tag's folder, and choose Paste.
Ignition creates a copy of the first tag and names it WriteableInteger2. Double click on the new Tag to open the Tag Editor.
In the Tag Editor, change the Data Type to Integer Array. Then click OK.
Once the Tag finishes re-subscribing, the value for WriteableInteger2 will now show "Array[16]" instead of the previous value. Expanding the Tag reveals a new Value section, and expanding this section will show the value of each bit.
Double click on the WriteableInteger2 Tag again to edit it. Scroll down to the Alarming section.
Click on the Edit icon.
Create a new alarm with Mode set to Equal, but change the Setpoint to "1," and then click Commit.
Click OK. Now an alarm will be active for each element that is set to 1.

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, the Tag History and Alarm systems do not support tags with dataset types.

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.
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.
In the Designer, on a new View, add a Table component.
Select the Table component. In the Property Editor, click on the Binding icon next to the data property.
On the Edit Binding screen, select Tag as the Binding Type.
Click the Browse Tag icon next to the Tag Path.
Navigate to the Dataset tag. Highlight the Tag in the list and then Click OK.
The Tag path is now displayed. Click OK.

These bindings, just like any other Tag binding, can be set to bi-directional. In this case, you would have to be able to somehow write to the data property using scripting for the bi-directional binding to work.
The Table component now displays the contents of the dataset.