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Understanding HistorianTags

When a solution Tag, or an external Asset, is mapped to be archived or retrieved from an Historian, that configuration is called a HistorianTag. 

When you define HistorianTags, you archive data by associating information with specific tags and HistorianTables in Storage Locations. In other words, you establish a link between Tags and HistorianTables to ensure systematic and organized data storage.

When archiving Tags created using DataTemplates, you don't need to specify all the properties.

The two pieces of Information that are mandatory to define an Historian Tags are:

TagName: variables that will archived, or retrieved.

HistorianTable: logical object that groups data and defines the storage location to which that variable will be connected.

Historian → Tutorial | Concept | How-to Guide | Reference

Configuration Properties

Creating Historian Tags

Prerequisites

• Configured HistorianTable (or use default Table1)
• Tags defined in Unified Namespace
• Understanding of collection requirements

Configuration Steps

1. Navigate to Historian → Historian Tags
2. Enter TagName or select from list
3. Configure deadband parameters:
   • DeadBand for value changes
   • Deviation for time overrides
   • RateOfChange for velocity triggers
4. Select DeviationDeadBandType
5. Choose target HistorianTable

Deadband Configuration

DeadBand (Value Change)

Minimum absolute change required for storage:

• Applied with SaveOnChange trigger
• Reduces database writes
• Filters noise and minor fluctuations

Example:

TagName: Tank.Level
DeadBand: 0.5
// Only stores when level changes by ±0.5 units

Deviation (Time Override)

Overrides TimeDeadBand interval when exceeded:

• Forces storage regardless of time interval
• Captures significant changes immediately
• Works with TimeDeadBand configuration

Example:

TagName: Reactor.Temperature  
Deviation: 5.0
TimeDeadBand: 60 seconds
// Stores every 60s OR when temp changes by ±5°

RateOfChange (Velocity)

Triggers on rapid value changes:

• Measured in units per second
• Detects process upsets
• Overrides time intervals

Example:

TagName: Pressure.Line1
RateOfChange: 10
// Stores when pressure changes >10 PSI/second

DeviationDeadBandType

Absolute

Fixed unit threshold:

Current Value: 100
Deviation: 5
Triggers at: <95 or >105

Percentual

Percentage of current value:

Current Value: 100
Deviation: 5 (%)
Triggers at: <95 or >105

Current Value: 200
Deviation: 5 (%)
Triggers at: <190 or >210

UserType Tags (Template Tags)

Archive entire templates or specific properties:

Full Template

TagName: Pump1
// Archives all properties of Pump1 template

Specific Property

TagName: Pump1.Motor.Current
// Archives only motor current property

Multiple Instances

When using template arrays:

TagName: Pumps[1].Flow
TagName: Pumps[2].Flow
// Individual configuration per instance

HistorianTable Assignment

Grouping Strategy

Assign tags to tables based on:

• Update frequency
• Process relationships
• Data types
• Storage requirements

Best Practices

Runtime Behavior

SaveOnChange Mode

Tag changes → Check DeadBand → Store if exceeded

Trigger Mode

Trigger fires → Store all table tags → Apply timestamp

TimeDeadBand Mode

Timer expires → Check Deviation/RateOfChange → Store if exceeded OR timer

Performance Optimization

DeadBand Settings

• Analog signals: 0.1-1% of range
• Digital signals: Usually 0 (all changes)
• Calculated values: Based on significance

Table Organization

• Group similar update rates
• Separate critical from non-critical
• Consider query patterns
• Balance table sizes

Storage Efficiency

• Use Normalized tables for sparse data
• Standard tables for synchronized data
• Enable compression where supported

Common Configurations

Temperature Monitoring

TagName: Furnace.Temperature
DeadBand: 0.5
Deviation: 10
RateOfChange: 5
DeviationDeadBandType: Absolute
HistorianTable: ProcessData

Level Tracking

TagName: Tank.Level
DeadBand: 0.1
Deviation: 5
DeviationDeadBandType: Percentual
HistorianTable: TankFarm

Discrete Events

TagName: Pump.Status
DeadBand: 0
HistorianTable: Events
// Captures all state changes

Troubleshooting

Data not archiving:

• Verify tag name spelling
• Check HistorianTable is active
• Review deadband settings
• Confirm tag has valid quality

Excessive storage:

• Increase deadband values
• Review deviation settings
• Check for oscillating tags
• Enable time deadband

Missing rapid changes:

• Decrease RateOfChange threshold
• Reduce deviation value
• Check scan rates
• Verify trigger configuration

Template tags not working:

• Confirm template structure
• Check property paths
• Verify array indices
• Review instance names

Best Practices Checklist

•  Set appropriate deadbands - Balance detail vs storage
•  Group related tags - Same table for correlated data
•  Document settings - Record why values chosen
•  Test configurations - Verify before production
•  Monitor performance - Track storage growth
•  Use templates efficiently - Archive needed properties only
•  Plan for maintenance - Consider future adjustments

In this section...

Configuring HistorianTags

Before setting HistorianTags, you need to configure a HistorianTable. To Know more about creating and configuring HistorianTables, click here. You can also use the default one (Table 1).

After configuring the HistorianTables, you can start defining which Tags to archive with the configured HistorianTables. To add and configure a single Tag, follow the steps below:

1. Access Historian / Historian Tags.

2. On the TagName column, type the Tag name or select from the available list. Alternatively, copy and paste the Tag's name from Unified Namespace / Tags.
   

3. Configure the DeadBand, Deviation, and RateOfChange. The following section describes each of these configurations.
   

4. Select if the platform should consider an Absolute or Percentual as the DeviationDeadBandType.

5. To finish, select the HistorianTable, where the Tags' information will be archived.

The image below illustrates the process described above.

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HistorianTags Properties

When configuring a HistorianTag, you need to specify some properties that will define how data will be archived. The following table describes each available property you can configure:

TagName

Specify the unique identifier of the Tag to be archived. To archive Template Tags, specify one of the Template Tag's properties or archive all properties by entering only the primary Tag name.

DeadBand

(Optional feature) Defines how much the value must change (in Units) for the system to store the value. This configuration is considered when you use the SaveOnChange option in the HistorianTable.

Deviation

(Optional feature) Specify how much the value must change (in Units) for the system to store the value. This configuration is considered when you use the TimeDeadBand option in the HistorianTable. If you define this property, its value overrides the TimeDeadband logging interval.

RateOfChange

(Optional feature) Defines how much the value must change (in Units) by second for the system to store the value. This configuration is considered when you use the TimeDeadBand option in the HistorianTable. If you define this property, its value overrides the TimeDeadband logging interval.

DeviationDeadBandType

(Optional feature) Determines the calculation method used to define the Deadband value.

HistorianTable

Select the HistorianTable to use when saving the Tag's value.

In this section: