UNS Tags Reference

Define and manage tags in your UNS.

UNS Tags (Reference) represent real-time variables and their associated historical records, providing a structured way to model process information by linking to physical devices, databases, or calculated values.

Tags in the Unified Namespace provide:

Real-time data representation
Historical record association
Device communication mapping
Hierarchical organization
Type-safe data handling
Array and template support

Tags form the foundation of the solution's data model, connecting field devices to visualization, logic, and storage.

Tag Types
Configuration Properties
Creating Tags
Tag Parameters
Domain Configuration
Visibility Levels
Retentive Options
Format Strings
Array Configuration
DataTable Tags
Runtime Attributes
Additional Configuration
Best Practices Checklist
Troubleshooting

Tag Types

Built-in Types

Digital	Int32	Binary value	0 or 1
Integer	Int32	Whole numbers	±2,147,483,647
Long	Int64	Extended integers	±9.2×10¹?
Double	Double	Floating point	±1.79×10³??
Decimal	Decimal	High precision	28-29 significant digits
Text	String	Unicode text	2GB max
Json	String	JSON structured data	Built-in parsing
DateTime	DateTimeOffset	Date and time	Year 0001-9999
TimeSpan	TimeSpan	Duration	Days to milliseconds
Guid	Guid	Unique identifier	128-bit
DataTable	DataTable	In-memory table	Structured data
Image	Byte[]	Binary content	Any size
Timer	Int32	Time patterns	Multiple modes

Timer Types

SquareWave	Toggle 0/1 at interval	Blinking, heartbeat
Pulse	Momentary 0→1→0	Triggers, events
DelayOff	Hold value then reset	TOF timer
Comparer	Daily schedule	Time-based control

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

Name	Unique tag identifier	Yes
Type	Data type selection	Yes
Path	Asset tree location	No
Array	Array size (0 to N)	No
StartValue	Initial value at startup	No
Parameters	Type-specific settings	No
Min/Max	Value limits	No
ScaleMin/Max	Engineering scale	No
Retentive	Value persistence	No
Domain	Server/Client scope	No
Visibility	External access level	No
Format	Display formatting	No
Units	Engineering units	No
Description	Documentation (1024 char)	No

Creating Tags

Method 1: Asset Tree

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

Method 2: Tags Grid

Go to Unified Namespace → Tags
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

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

Server	Global across all clients	Device data, shared values
Client	Local to each session	User settings, local states

Visibility Levels

Private	None	Internal only
Protected	Read-only	Monitor only
Public	Read/Write	Full access

Affects: OPC UA Server, MQTT Broker, TcpDataAccess

Retentive Options

None	Nothing	Temporary values
ValueOnly	Value only	Operator setpoints
Properties	All including value	Complete state
PropertiesOnly	All except value	Configuration

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

Value	Tag Type	Current value
Quality	Integer	OPC quality (0/64/192)
Timestamp	DateTimeOffset	Last change time

Quality Codes

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

Additional Configuration

Device Integration

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

Alarm Settings

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

Historian

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