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Tags are points of data and may have static values or dynamic values that come from an OPC address, an Expression, or a SQL query. The values can be used on screens, in Transaction Groups, and more. Additionally, Tags offer a core set of features above and beyond simple values, such as scaling, alarming, and history logging. Depending on the specific type of Tag, even more options are available. In general, Tags provide a common interface for tying together many types of data in Ignition.

Tag Configuration in the Designer

Tags are managed in the Tag Editor. To configure a Tag, right-click on it and select Edit Tag. Or create a new Tag by right-clicking on the Tags folder in the Tag Browser and use the New Tag option to select a new Tag type.

 

Once the Tag Editor window is displayed you can set the properties for that Tag. The Tag Editor window has the following sections depending on the type of Tag you are creating:

  • Basic Properties
  • Value
  • Numeric Properties
  • Meta Data Properties
  • Security
  • Scripting
  • Alarms
  • History

On this page ...


Tag Object Types

Some features, such as system.tag.browse, can access the Object Type of the tag (sometimes called "tagType"). Below is a table representing the possible types. 

Tag ObjectType
Property
A single value underneath an node.
Node
An entity that may have a value and may have children. "Node" is a generic term for other objects in this table, such as a Folder or AtomicTag. 
Folder
Represented by a folder in the Tag Browser. Folders generally have child nodes, but don't have values or other properties that make up a tag. 
AtomicTag

A "normal" type of tag. Objects with this type can be one of the following (based on the Value Source property):

  • OPC Tag
  • Query Tag
  • Expression Tag
  • Derived Tag
  • Reference Tag
  • Memory Tag
UdtInstance

An instance of a complex tag instance (UDT Instance). It's important to note that UdtInstances contain other nodes, so this type is generally only seen at the root of a UDT instance.

Thus, nodes under a UdtInstance are not considered to have a type of "UdtInstance", unless the child node is actually a UdtInstance: in other words, a nested UDT instance. 

UdtType
Represents the root of a complex tag definition (UDT Definition). Similar to UdtInstance, nodes under a UdtType have their own object type, so a UdtType represents the root of a complex tag.
Provider
Represents a Tag Provider. 


Standard Tag Properties Table

This following table provides detail on each Tag Property, including the binding name, description, data type, and the Tag Types that use the property.

Property 

JSON/Scripting Name 

Description

Data Type

Applicable Tag Type

Basic Properties
Name name How the Tag will be presented and referenced in the system. The Tag path will be the provider, the folder structure, and this name.

StringOPC, Query, Expression, Derived, Client, Reference, Memory
Tag GrouptagGroup The Tag Group that will execute the Tag. The Tag Group dictates the rate and conditions on which the Tag will be evaluated. For more details, see Tag Groups.StringOPC, Query, Expression, Derived, Reference, Memory
Enabledenabled Whether the Tag will be evaluated by the Tag Group. If false, the Tag will still be present, but will have a bad quality.BooleanOPC, Query, Expression, Derived, Reference, Memory

Value

Value SourcevalueSource

Specifies how the Tag determines its value. In other words, sets the type of the Tag (Memory, OPC, Expression, etc).

 Click here to see valid values
Value SourceJSON Name
Derived
derived
Expression
expr
Memorymemory
OPCopc
Querydb
Reference
reference

String

OPC, Query, Expression, Derived, Reference, Memory
Data TypedataType

The data type of the Tag. It is important that this be set as correctly as possible with regards to the Tag's underlying data source. The Tag system will attempt to coerce any raw incoming value (for example, from OPC or a SQL query) into the desired type. For detailed information, see Tag Data Types.

 Click here to see valid values
Data TypeString ValueInteger Value
Byte
Int1
0
Short
Int2
1
Integer
Int4
2
Long
Int8
3
Float
Float4
4
Double
Float8
5
Boolean
Boolean
6
String
String
7
DateTime
DateTime
8
Text
Text
10
Byte Array
Int1Array
17
Short Array
Int2Array
18
Integer Array
Int4Array
11
Long Array
Int8Array
12
Float Array
Float4Array
19
Double Array
Float8Array
13
Boolean Array
BooleanArray
14
String Array
StringArray
15
DateTime ArrayDateTimeArray16
Binary DataByteArray20
Dataset
DataSet
9
DocumentDocument29

Note: Regarding Array data types, Alarming, Scaling, and Historical settings applied to an array Tag are propagated down to elements in the array. 

String

OPC, Query, Expression, Derived, Reference, Memory
Value

value

The value of the Tag. Can only be modified if the Tag allows value writing and the user has sufficient privileges.Object (depends on the data type of the Tag)Memory
OPC ServeropcServer Only p resent for OPC Tags. The server against which to subscribe the data point. Only present for OPC Tags.StringOPC
OPC Item PathopcItemPath Only present for OPC Tags. The path to subscribe to on the server. The point will be subscribed at the rate dictated by the Tag Group.StringOPC
Source Tag PathsourceTagPathThe path to the Tag that this Tag is referencing. Only present for Reference and Derived Tags.StringDerived, Reference
Execution ModeexecutionMode

Only present for Query and Expression Tags . Determines how when the Tag executes.

  • Event Driven - Updates when something happens (i.e., value event or alarm event) within the expression.
  • Fixed Rate - Tag will be executed at the set or fixed rate. Adds the Execution Rate property, which determines how often the Tag executes in milliseconds.
  • Tag Group - Tags are executed by Tag Groups, which dictate the rate of execution.
Execution ModeJSON Name
Event Driven
EventDriven
Fixed Rate
FixedRate
Tag Group
TagGroupRate

String

Expression, Query
Expression

expression

The expression the Tag will use to determine its value.

StringExpression
Read Expression

deriveExpressionGetter

The expression that determines how the value on the Derived Tag is displayed.StringDerived
QueryqueryThe SQL query to be run, which drives the tag's value. Queries doing database reads and writes are possible, see the Query Type property description for details.

Write Expression

deriveExpressionSetter

The expression that determines how the value on the Derived Tag is displayed.StringDerived
Datasource

datasource

The database connection that the query Tag will execute against.

StringQuery
Query TypequeryType

The following feature is new in Ignition version 8.1.3
Click here to check out the other new features
Defines whether the query is executing a database read or a database write. Important for determining the value behavior of the Tag.

Possible values are:

  • AutoDetect - Query type is determined from the query itself.
  • Select - Dictates that the query is reading data from the database. The query result set will be stored on the Tag's value.
  • Update - Dictates that the query is writing data to the database (but does not require an UPDATE statement in the query, specifically). The value on the query Tag will be the number of affected rows.
StringQuery
Numeric Properties
Deadband deadband A numerical value used to prevent unnecessary updates for Tags whose values change by small amounts.Numeric OPC, Query, Expression, Derived, Reference, Memory
Deadband ModedeadbandMode

Defines how the deadband value is used.

  • Absolute - The deadband setting is considered to be an absolute value.
  • Percent - The actual deadband is calculated as a percent of the Tag's engineering unit span.

Valid values are as follows:

Deadband ModeJSON Name
Absolute
Absolute
Percent
Percent
String

OPC, Query, Expression, Derived, Reference, Memory

Scale ModescaleMode 

If and how the Tag value will be scaled between the source, and what is reported for the Tag.

Valid values are as follows:

ModeJSON NameInt Value
Off
Off
0
Linear
Linear
1
Square Root
SquareRoot
2
Exponential Filter
ExponentialFilter
3
Bit Inversion
BitInversion
4

String

OPC, Query, Expression, Derived, Reference, Memory
Raw LowrawLowStart of the "raw" value range. Only present if Scale Mode is set to Linear or Square Root.NumericOPC, Query, Expression, Derived, Reference, Memory
Raw HighrawHigh

End of the "raw" value range. Only present if Scale Mode is set to Linear or Square Root.

NumericOPC, Query, Expression, Derived, Reference, Memory
Scaled LowscaledLowStart of "scaled" value range. Raw low will map to Scaled low for the Tag. Only present if Scale Mode is set to Linear or Square Root.NumericOPC, Query, Expression, Derived, Reference, Memory
Scaled HighscaledHighEnd of "scaled" value range. Raw high will map to Scaled high for the Tag. Only present if Scale Mode is set to Linear or Square Root.NumericOPC, Query, Expression, Derived, Reference, Memory
Clamp ModeclampMode

How values that fall outside of the ranges will be treated. "Clamped" values will be adjusted to the low/high scaled value as appropriate. Only present if Scale Mode is set to Linear or Square Root.

Valid values are as follows:

Clamp ModeJSON NameInt Value
No_Clamp
No_Clamp
0
Clamp_Low
Clamp_Low
1
Clamp_High
Clamp_High
2
Clamp_Both
Clamp_Both
3

String

OPC, Query, Expression, Derived, Reference, Memory
Scale FactorscaleFactorFor single parameter modes (currently only Exponential Filter), the factor parameter for the equation. Used when the Scale Mode property is set to Exponential FilterNumeric

OPC, Query, Expression, Derived, Reference, Memory
Engineering UnitsengUnit The engineering units of the value.StringOPC, Query, Expression, Derived, Reference, Memory
Engineering Low LimitengLow The lowest expected value of the Tag.NumericOPC, Query, Expression, Derived, Reference, Memory
Engineering High LimitengHigh The highest expected value of the Tag.NumericOPC, Query, Expression, Derived, Reference, Memory
Engineering Limit ModeengLimitMode 

Dictates how the engineering range should be enforced on the Tag. If not "Off", the Tag will change to bad quality ("limit exceeded"), when the value falls outside the specified range.

Valid values are as follows:

Limit EnforcementJSON NameInt Value
No_Clamp
No_Clamp
0
Clamp_Low
Clamp_Low
1
Clamp_High
Clamp_High
2
Clamp_Both
Clamp_Both
3

Numeric

OPC, Query, Expression, Derived, Reference, Memory
Format StringformatString 

How the value should be formatted when converted to a string (only applies to numerical data types). Uses # and 0 characters to describe the format.

# : If the number in this position is non-zero, then do not show the position. Otherwise, show the number. Useful when you only want to show a decimal position if the value is non-zero.

0 : If the number in this position is non-zero, then show that number. Otherwise, show a zero. Useful to add leading and trailing zeros to a value.

See Data Type Formatting Reference.

StringOPC, Query, Expression, Derived, Reference, Memory
Meta Data Properties
Tooltip tooltip The tooltip provides a hint to visual components as to what should be displayed when the user hovers their mouse cursor over the component that is being driven by the value of this Tag.StringOPC, Query, Expression, Derived, Reference, Memory
Documentation documentation 

A freeform text property for information about the Tag.

StringOPC, Query, Expression, Derived, Reference, Memory
Security

Read Permissions


readPermissions

Defines the security levels required in order to read values from a Tag.  For more information, see Tag Security Properties. Contains the following elements:

NameJSON NameDescription
Type
type

Represents the selected radio button on the security level UI, determining if all of the elements in the securityLevels array are required, or if any of the elements are allowed. Possible values are:

AnyOf
AllOf
Security LevelssecurityLevels

Represents allowed security levels for this permission. Each level is represented as a JSON object, containing a "name" value that represents the name of a security level, and a "children" array which represents any levels under the current. The actual "selected" levels are any levels that have an empty "children" object. See the example below for more information. 



 Click here to see an example in JSON...

The JSON in this example uses the configuration shown in the image below. Permission is granted if the security levels on the request are from either an "Administrator" user, or if the request originated from the "Zone A" Security Zone. 

"readPermissions": {
    "type": "AnyOf",
    "securityLevels": [
      {
        "name": "Authenticated",
        "children": [
          {
            "name": "Roles",
            "children": [
              {
                "name": "Administrator",
                "children": []
              }
            ]
          }
        ]
      },
      {
        "name": "SecurityZones",
        "children": [
          {
            "name": "Zone A",
            "children": []
          }
        ]
      }
    ]
  }
JSON ObjectOPC, Query, Expression, Derived, Reference, Memory

Read Only

readOnly

Defines whether a Tag is read-only or writeable. For more information, see Tag Security Properties

value: booleanOPC, Query, Expression, Derived, Reference, Memory
Write Permissions 
writePermissions

Defines the security levels required in order to read values from a Tag. For more information, see Tag Security Properties. Contains the following elements:

NameJSON NameDescription
Type

type

Represents the selected radio button on the security level UI, determining if all of the elements in the securityLevels array are required, or if any of the elements are allowed. Possible values are:

AnyOf
AllOf
Security Levels

securityLevels

Represents allowed security levels for this permission. Each level is represented as a JSON object, containing a "name" value that represents the name of a security level, and a "children" array which represents any levels under the current. The actual "selected" levels are any levels that have an empty "children" object. See the example below for more information. 
 Click here to see an example in JSON...

The JSON in this example uses the configuration shown in the image below. Permission is granted if the security levels on the request are from either an "Administrator" user, or if the request originated from the "Zone A" Security Zone. 

"writePermissions": {
    "type": "AnyOf",
    "securityLevels": [
      {
        "name": "Authenticated",
        "children": [
          {
            "name": "Roles",
            "children": [
              {
                "name": "Administrator",
                "children": []
              }
            ]
          }
        ]
      },
      {
        "name": "SecurityZones",
        "children": [
          {
            "name": "Zone A",
            "children": []
          }
        ]
      }
    ]
  }
JSON ObjectOPC, Query, Expression, Derived, Reference, Memory
Scripting
Tag Event Scripts
eventScripts

Each Tag has the option to have Tag Event Scripts on it. When you edit a Tag, you can navigate to the Tag Events screen to see a list of all of the Tag scripts. You can then select which event you would like to write a script for. You can even write a script for multiple events if you like. For detailed information, see Tag Event Scripts .

When interacting with a Tag from a script, the Tag Event Scripts are represented as an array of JSON objects. Each JSON object is described in the expandable area below:

 Click here to expand...

Key Description

KeyDescription
eventidA value representing the type of event script
scriptA value representing the content of the script

Possible eventid values

Event Scripteventid value
Quality Changed
qualityChanged
Value Changed
valueChanged
Alarm Active
alarmActive
Alarm Cleared
alarmCleared
Alarm Acknowledged
alarmAcked

JSON Array

OPC, Query, Expression, Derived, Reference, Memory
Alarms
Alarms
alarms

Tags have the ability to define any number of alarms. Each alarm is a condition that will be evaluated when the value of the Tag changes. When the condition becomes true, the alarm is said to be active. When it becomes false, the alarm is said to be cleared.

For detailed information, see Tag Alarm Properties.

JSON Array of JSON objects. For detailed information, see Tag Alarm Properties . OPC, Query, Expression, Derived, Reference, Memory
History
History EnabledhistoryEnabledWhether the Tag will report its history to the Tags Historian system.BooleanOPC, Query, Expression, Derived, Reference, Memory
Storage ProviderhistoryProviderWhich Tag Historian data store the Tag will target. A particular Tag can only target one history store. For more information, refer to History Providers on the Tag History Gateway Settings page.StringOPC, Query, Expression, Derived, Reference, Memory
Deadband StylehistoricalDeadbandStyle

There are three styles to choose from: Auto, Analog, or Discrete.

When set to Auto, this setting will automatically pick from Analog or Discrete, based on the data type of the Tag.

  • If the data type of the Tag is set to a float or double, then Auto will use the Analog Style
  • If the data type of the Tag is any other type, then the Discrete style will be used.

More information on the Analog and Discrete types can be found on the Configuring Tag History page.

Valid values are as follows:

Deadband Style

JSON Name

Auto
Auto
Analog
Analog
Discrete
Discrete

String

OPC, Query, Expression, Derived, Reference, Memory

Deadband ModedeadbandMode

Defines how the deadband value is used.

  • Absolute - The deadband setting is considered to be an absolute value.
  • Percent - The actual deadband is calculated as a percent of the Tag's engineering unit span.

Deadband Mode

JSON Name

Absolute
Absolute
Percent
Percent

String

OPC, Query, Expression, Derived, Reference, Memory

Historical DeadbandhistoricalDeadband

A deadband that applies only to historical evaluation.

NumericOPC, Query, Expression, Derived, Reference, Memory
Sample ModesampleMode

Determines how often a historical record should be collected.

  • On Change - Collects a record whenever the value on the Tag changes.
  • Periodic - Collects a record based on the Sample Rate and Sample Rate Units properties.
  • Tag Group - Collects a record based on the Tag Group specified under the Historical Tag Group property.

Valid values are as follows:

Max Time Between Records ModeJSON Name
On Change
OnChange
Periodic
Periodic
Tag Group
TagGroup

String

OPC, Query, Expression, Derived, Reference, Memory
Sample Rate

historySampleRate

When the Sample Mode property is set to "Periodic", this property (working in conjunction with the Sample Rate Units property) determines how often a record should be collected.NumericOPC, Query, Expression, Derived, Reference, Memory
Sample Rate Units

historySampleRateUnits

When the Sample Mode property is set to "Periodic", this property (working in conjunction with the Sample Rate property) determines the unit of time that will be use in record collection.

 Click here to see valid values
Unit of TimeJSON Name
Milliseconds
MS
Seconds
SEC
Minutes
MIN
HourHOUR
DayDAY
WeekWEEK
MonthMONTH
YearYEAR

String

OPC, Query, Expression, Derived, Reference, Memory
Historical Tag Group

historyTagGroup

When the Sample Mode property is set to "Tag Group", this property determines which Tag Group will be used to collect records.StringOPC, Query, Expression, Derived, Reference, Memory
Min Time Between SampleshistoryTimeDeadband

Minimum time between records. Useful in restricting the number of records collected when the Sample Mode is set to "Tag Change". Prevents multiple consecutive Tag changes from triggering consecutive record collections. Works in conjunctions with the Min Time Units property. The Value is calculated off of the value timestamp. 

IntegerOPC, Query, Expression, Derived, Reference, Memory
Min Time UnitshistoryTimeDeadbandUnits

Units of time to use with the Min Time Between Samples property.

 Click here to see valid values
Unit of TimeJSON Name
Milliseconds
MS
Seconds
SEC
Minutes
MIN
HourHOUR
DayDAY
WeekWEEK
MonthMONTH
YearYEAR

String

OPC, Query, Expression, Derived, Reference, Memory
Max Time between Samples historyMaxAge
Maximum time between samples. Works in conjunction with the Max Time Units property. If a sample has not been collected by the time range specified by these two properties, then a record will be collected on the next sample interval.Integer OPC, Query, Expression, Derived, Reference, Memory
Max Time UnitshistoryMaxAgeUnits

Maximum time in units is defined as: Milliseconds, Seconds, Minutes, Hours, Days, Weeks, Months, and Years.

 Click here to see valid values
Unit of TimeJSON Name
Milliseconds
MS
Seconds
SEC
Minutes
MIN
HourHOUR
DayDAY
WeekWEEK
MonthMONTH
YearYEAR

String

OPC, Query, Expression, Derived, Reference, Memory


Custom Tag Properties

Custom Tag properties allow application designers to configure their own properties on Tags to store unique values on any Tag. Once added, a custom property can be referenced like any other Tag property via bindings, expressions, and scripts.

Both the Perspective and Vision visualization systems can bind to custom properties. In the following example, we already have Array Tag. Now let's add a custom property. 

  1. Open an existing Tag and click on the Add  icon in the Tag Editor.
  2. This opens the Custom Property dialog box. Enter a Name for your Tag, select the Data Type, and click OK. 



  3. Scroll down to the bottom of your Tag properies and you'll see your Custom Property. We added the value "Hello Ignition". 




  4. When you open your Tag Browser and expand the My Array Tag, you'll see your Custom Property.

IULocgo


Custom Tag Properties


Vision Client Tags

Client Tags have the ability to be used as either Expression or SQL Query Tags. There is an Expression/SQL page in the Tag editor that allows you to select what type it is.

Query/Expression Attributes

Property

Binding/Scripting Name

Description

Data Type

Applicable Tag Type

OPC ServerOPCWriteBackServerThe server against which to subscribe the data point.StringQuery, Expression
OPC Item PathOPCWriteBackItemPathThe path to subscribe to on the server.StringQuery, Expression
QueryExpressionText area to build your query or expression.

String

This is the code used by the Tag: either a SQL Query for Query Tags, or an Expression for Expression Tags.

Query, Expression
Query Type

QueryType

When the TagType property is set to 1, this property determines if the Tag should be a Memory, Expression, or Query Tag.


Integer

 Click here to see supported values
Tag TypeInteger Value
Memory Tag
0

Expression Tag

1
Query Tag2
Query, Expression, Memory
DatasourceSQLBindingDatasourceThe default data source of the Tag provider.StringQuery



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