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Complex Tags, also referred to as Tag UDTs (user defined types), offer the ability to leverage object-oriented data design principles in Ignition. Using complex tags, you can dramatically reduce the amount of work necessary to create robust systems by essentially creating parameterized "data templates" that can be used to generate tag instances.
Primary Features
| • | Central Definition - Once you define your data type, you can then create instances of it. If at a later time you want to change some aspect of the tag, you can simply edit the type definition, and all instances will be automatically updated. |
| • | Parameterized Settings - Define custom parameters on your data type, and then reference them inside your member tags. When it comes time to create instances, you can simply modify their parameter values in order to change where the underlying data comes from. |
| • | Extendable - Data types can inherit from other data types in order to add additional members, or override settings. Instances can also override settings, allowing for flexibility for dealing with irregular data and corner cases. |
Terminology
Many terms are frequently used when discussing complex tags:
| • | UDT or UDDT - User Defined Type or User Defined Data Type. The definition of the data type: its structure, tags, attributes and settings. |
| • | Instances - Running copies of a data type, with concrete data for all members. Instances are linked to their parent types, and are reloaded when their parent type changes. Besides specifically overridden settings, all settings are inherited from the type definition. |
| • | Parameters - Custom properties on data types that can be used inside the type or instance definition to create parameterized data templates. For example, if a data type consists of 3 OPC tags that only differ by a number in the path, a parameter can be used for the "base address", allowing instances to be created with only 1 setting. |
| • | Members - The tags inside of a data type or instance. |
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