Iotellect SCADA/HMI Tags

In Iotellect SCADA/HMI, tags represent process values used by SCADA applications.

A process value, such as temperature, pressure, level, flow rate, or rotation angle, may be received from one or more device accounts. A device account represents an external data source configured in Iotellect, for example, a controller, sensor, protocol device, or gateway connection.

Iotellect SCADA/HMI represents source-specific values as device tags and can bind them to digital twin tags. A digital twin tag is a Digital Twin variable used as the SCADA process value of a modeled object.

Operator screens, dashboards, alerts, charts, reports, history, and business logic use digital twin tags. Individual device tags remain available for diagnostics and maintenance.

This approach keeps the operator interface stable. Operators continue to work with one process value, while the system selects the appropriate device tag according to configured quality, availability, and priority rules.

In the Iotellect SCADA/HMI module, tags are implemented using Iotellect variables and configured on the Tag Tree screen.

A device tag is a source-specific value received from a a variable or field of a device account.

Device tags are used as input values to calculate the digital twin tag value. They also provide information about the quality of the value received from the source. This quality can be used for diagnostics and active device tag selection.

A digital twin tag is a Digital Twin variable that represents a SCADA process value of a modeled object.

Iotellect SCADA/HMI components use digital twin tags instead of device tags to keep screens, dashboards, alerts, charts, reports, history, and business logic independent from the device account that currently provides the value.

Device tag to digital twin tag binding defines which device tags provide values for a digital twin tag.

One digital twin tag may be bound to one or more device tags. When several device tags are bound to the same digital twin tag, Iotellect SCADA/HMI calculates the digital twin tag value according to configured rules.

The rules may consider device tag quality, availability, timestamp, configured priority, communication state, or other implementation-specific criteria. For example, Iotellect SCADA/HMI can switch to another device tag when the current source loses communication or reports bad quality.

The active device tag is the device tag currently used to calculate the digital twin tag value.

The active device tag may change when the current device tag becomes unavailable, reports bad quality, loses communication, or is replaced by a higher-priority device tag according to the configured switch model.

The digital twin tag name does not change when the active device tag changes. This keeps the operator interface stable.

Tags are configured in the Tag Tree screen. The Tag Tree provides a SCADA-specific view of process values and their bindings. It shows only the objects and values that describe the monitored system, without exposing unrelated service variables, configuration settings, or internal platform resources.

The Tag Tree is based on the Digital Twin hierarchy. Digital Twins and their instances define the object structure displayed in the tree. For example, an Application may contain sites, production areas, devices, sensors, pumps, valves, or other modeled objects. The hierarchy may be created manually or generated by the Application Creation Wizard.

When a user selects an object in the Tag Tree, Iotellect SCADA/HMI displays the tags associated with this object. Selecting a higher-level object shows tags for the corresponding part of the hierarchy. Selecting a template can be used to view all tags associated with its instances.

A tag is added to a modeled object in the Tag Tree. One tag normally represents one process value, such as temperature, pressure, humidity, pump state, valve position, or rotation angle.

When adding a tag, configure its properties:

The Sources property defines which device tag provides a value for the digital twin tag. One digital twin tag may have one or more sources. Several sources are used when the same process value can be received from different devices, controllers, gateways, device accounts, or communication paths.

To configure a source for a tag, define the following:

Source configuration is part of device tag to digital twin tag binding. It defines how source-specific values become the process value used by the Iotellect SCADA/HMI application.

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