The following example shows a pressure Tag in the Tag Browser and a Gauge component in the Designer. The value on the Designer component is bound to the Tag and updates in realtime. This is just a simple example of how Tag values can be represented in your SCADA designs.
There are two types of Tag providers; Internal and Remote. By default, a fresh Ignition installation will have an internal Tag provider. This can be thought of as a standard internal Tag database, and stored in the Ignition Gateway. Additionally, it is possible to create Remote Tag Providers, linking one installation of Ignition to the Tags on another Ignition. This ability opens up some very flexible architectures.
Tag User Defined Types
Tag User Defined Types (UDTs) provide an object-oriented approach to Tag building, allowing you to define parameterized data types, extend and override types, and then rapidly generate instances. A change to the type definition is then inherited by all instances, drastically saving time when making routine changes. The UDTs are fully supported by Vision templates, which means you can configure templates for your custom data types and take advantage of drag-and-drop binding to rapidly build complex screens.
Ignition Tags or PLC Tags?
In this manual, we refer to Ignition Tags as simply "Tags." Any mentions of tags from a PLC or another OPC Server will be referred to as "PLC tags" or "OPC tags."
Tags work naturally and easily with Ignition to offer the following features:
Performance and Scalability
Tags offer great performance on the Gateway, in Perspective Sessions, and in the Vision Client. On the Gateway, the system can support many thousands of value changes per second and millions of Tags. In runtime, Tags improve efficiency with their lightweight subscription architecture. Adding additional Clients creates a nearly negligible effect on the database and the Gateway performance.
Use Tag UDTs (User Defined Types) to design re-usable, parameterized, and extendable data types. You can create and configure new instance Tags in seconds, saving a great amount of time over traditional Tag systems.
Powerful Alarming Model
Each Tag can have any number of alarms configured on it. There are many different alarm modes accommodating simple digital alarms, analog high/low value alarms, as well as more specialty alarms like bad data quality and bit-packed alarms. The settings for alarms can bound to other Tags, making the alarm configuration dynamic.
Drag-and-Drop Screen Design
You can drag and drop Tags onto a window or view to automatically create new bound components. Drag Tags onto existing components or properties to quickly bind them to the data.
- Historical Logging
The Tag Historian Module makes it easier than ever to store and use historical data. When you simply select a check box on a Tag, historical data is stored in an efficient format in your SQL database. This data is then available for querying through scripting, historical bindings, and reporting. Also, you can drag-and-drop Tags directly onto an many components to create trends or display historical values. Tags Historian's robust querying provides you great flexibility in how you retrieve the data.
Integrated Component Feedback
Tags offer a quality and overlay system for components. If a Tag's data quality is anything but good, a component that depends on it gets a visual overlay. Input components display an animated overlay while write pending requests are being written. These features effectively communicate the status of the system at a glance.
Importing and Exporting Tags
Ignition Tags can easily be imported and exported from the Designer by selecting the Tags or folders that you want. See the Exporting and Importing Tags page for more information.