UNS Tags Reference

Define and manage tags in your UNS.

Reference → Modules → UNS → UI → Asset | Tags | UserTypes | Enumerations | Services | Monitor

Tag Types

Built-in Types

Timer Types

Reference Type

Dynamic tag addressing:

// Set reference target
@Tag.Reference1.Link = @Tag.TankFarm/Tank1/Level.GetName();

// Use reference
double level = @Tag.Reference1.Value;

Configuration Properties

Ontology metadata columns (10.1.5+)

Tags in 10.1.5 carry three ontology columns alongside their real-time data: Labels, SourceIri, and Attributes. These columns populate from RDF/OWL individuals imported by the ontology importer and round-trip back through Export UNS → RDF / JSON.

• Labels — semicolon-delimited alternative names. Imports from skos:altLabel and skos:hiddenLabel. Searchable via search_uns (Designer) and runtime_search_uns (runtime) with one canonical scoring algorithm.
• SourceIri — full source IRI for the individual. External-system join key. Preserved on re-export, so round-trip is lossless.
• Attributes — JSON column for ontology annotations not covered by other columns (dcterms:*, alt-language labels keyed rdfs:label@pt, skos:note, owl:versionInfo, custom predicates).

Mutability & retention

Tag ontology columns follow a class-vs-instance split shared with UserType and member-def columns (see UNS UserTypes Reference):

Tag Labels and Attributes are the only ontology columns an operator, script, or UI can mutate at runtime. Writes land in the retentive database and survive restarts. Use promote_retentive_attributes before export to roll runtime overlays back into the cold-start data so the exporter produces a deterministic RDF/OWL file. Bindings can read all three columns but writes go through the property setter (script) or the planned operator UI — never through binding-write directly. SourceIri is the tag's ontology identity and never changes at runtime: if a rename is needed, re-import with owl:sameAs.

See Industrial Ontology Integration How-to for the full model.

AI / MCP page action (10.1.5+)

When Designer is navigated to the Tags page, the following action is exposed via the designer_action MCP tool:

• designer_action("export_graph", "rj") — mirrors the Export UNS toolbar dropdown. Accepts four W3C RDF formats — format=rj (RDF/JSON, default; the format the ontology importer round-trips and the most compatible with graph stores like GraphDB / Stardog / Fuseki), format=jsonld (JSON-LD), format=turtle (alias ttl), and format=ntriples (alias nt). All four are native emitters in 10.1.5. The exported file lands in the solution's Exchange folder.

The action is listed in the tabActions array returned by get_state() only when the Tags tab is active. See Export your UNS to RDF/OWL/GraphDB for the broader export reference.

Creating Tags

Method 1: Asset Tree

1. Navigate to Unified Namespace → Asset Tree
2. Right-click folder or click New Tag icon
3. Enter tag name and properties

Method 2: Tags Grid

1. Go to Unified Namespace → Tags
2. Options:
   • Click New Item for dialog
   • Type directly in Name column
   • Paste from external source

Method 3: Import

• Copy from another solution
• Import from CSV files
• Use Solution Import Tools
• EngWrapper API

Tag Parameters, Type Specific Settings

Deadband

Limits value updates:

Absolute: ±5 units from last value
Percentage: 10% change required

EnumerationSet

Map values to text:

0 → "Off"
1 → "On"
2 → "Auto"

Domain Configuration

Visibility Levels

Affects: OPC UA Server, MQTT Broker, TcpDataAccess

Retentive Options

Storage: Dataset.DB.Retentive database

Format Strings

Numeric Formats

N0    → 123        (no decimals)
N2    → 123.45     (2 decimals)
C     → $123.00    (currency)
P     → 12.34%     (percentage)
X     → 7B         (hexadecimal)
E     → 1.23E+02   (scientific)

DateTime Formats

d     → 3/15/2024  (short date)
T     → 14:30:00   (long time)
yyyy-MM-dd HH:mm:ss → 2024-03-15 14:30:00

Array Configuration

Array size N creates elements [0] to [N]:

Array = 5 creates:
Tag[0], Tag[1], Tag[2], Tag[3], Tag[4], Tag[5]
(6 elements total)

DataTable Tags

Using Queries

@Tag.DataTableTag = @Dataset.Query.MyQuery.SelectCommand();

Manual Population

@Tag.DataTableExample.StartBlockSet();
@Tag.DataTableExample[1].Column1 = value1;
@Tag.DataTableExample[2].Column2 = value2;
@Tag.DataTableExample.CommitBlockSet();

Runtime Attributes

Core Properties

Quality Codes

• 0: Bad quality
• 64: Uncertain quality
• 192: Good quality

Quality on a comms or sync drop

When the connection that feeds a tag is lost — a device communication failure (read retries exhausted, node or channel failure) or a broken redundancy / remote-server sync link — the runtime does not leave the affected tags frozen at their last-good value pretending to still be live. Instead it forces Quality to Bad (0) and raises the change as a normal Changed event, so every consumer — displays, scripts, alarms, the Historian, OPC UA / MQTT publishers — sees the staleness on the next update rather than reading a stale value as if it were current.

Lifecycle

The value being kept (rather than blanked) means a display still shows the last reading, but it is now flagged Bad — the quality, not the value, is what tells you it is no longer live.

Additional Configuration

The TagNames are frequently reference in these other configuration Tables:

DevicesPoints

• Node: Communication node
• Address: PLC/device address
• AccessType: Read/Write/ReadWrite

AlarmsItems

• Condition: Trigger logic
• Groups: Alarm categorization
• Limits: Threshold values

HistorianTags

• Table: Storage location
• Deadband: Recording threshold
• DeadbandType: Absolute/Percentage

Best Practices Checklist 

• Use meaningful names - Follow naming conventions
• Set appropriate types - Match data characteristics
• Configure retentive - Preserve critical values
• Apply deadbands - Reduce unnecessary updates
• Document tags - Use Description field
• Organize in assets - Logical hierarchy
• Set security - Control access levels

Troubleshooting

Tag not updating:

• Check device communication
• Verify Quality = 192
• Review deadband settings
• Confirm not disabled

Wrong value format:

• Check Format string
• Verify Units configuration
• Review scale settings

Array issues:

• Confirm index in range
• Check array size setting
• Verify element access

Retentive not working:

• Check database connection
• Verify retentive setting
• Review database permissions

In this section...