Semantic Tags

Semantic Tags let you label the meaning of a datastream's data — for example, temperature, battery level, or RSSI — so Blynk can power smarter dashboards, column management, automations, and device analytics automatically.

Sementic Tags in Datastream Settings

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Tag types

There are two types of Semantic Tags:

System Tags are a built-in set of predefined tags (see the reference tables below). They connect datastreams to system-wide logic — auto-aggregated views, Developer Tools panels, column management, and data visualizations. Only one System Tag can be assigned per datastream. Some System Tags are also restricted to one per template, meaning no two datastreams in the same template can hold the same System Tag.

Custom Tags are tags you create yourself. They are primarily used for grouping device properties across different products (templates), making it possible to build cross-product automations, dashboards, and device list views. Up to four Custom Tags can be assigned per datastream.

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How to assign Semantic Tags

1. Open a Template in Blynk.Console.

2. Navigate to Datastreams and open or create a datastream.

3. In the Semantic section, locate the Semantic Tags (Optional) field.

4. Click + Add to open the tag picker.

5. Add up to 5 tags (1 system tag and up to 4 custom tags).

6. Click Save.

Note: Semantic Tags are optional. Datastreams without tags work normally, but assigning tags enables automatic dashboard column management, Automation grouping, Developer Tools panels, and device metric detection.

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System Tag settings suggestions

When you select a System Tag, Blynk suggests recommended settings for the datastream — Data Type, Units, and Min/Max values — based on the expected signal characteristics. You can apply the suggestions or skip them.

Applied settings can still be overridden manually. However, if a System Tag specifies a set of supported Data Types, you cannot select a Data Type outside that supported set.

Suggested Datastream Settings by Semantic Tags

Pro Tip: Use System Tags for well-known signals (such as RSSI or Battery Level) to get suggested datastream settings and automatically populated Developer Tools panels.

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Creating a custom Semantic Tag

To create a new Custom Tag:

1. In the Semantic section of a datastream, click Add a custom tag.

2. Type the name of the new tag.

3. Select Create at the top of the list to create and apply it.

Custom Tags are available across all templates in your organization. Once created, a Custom Tag can be assigned to datastreams in any template — making it easy to group equivalent properties across different products.

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Handling complex use cases

When a template has multiple datastreams representing the same measurement type in different contexts, assign multiple tags to each datastream to differentiate them.

Examples:

• A device reporting three temperature readings — Current, Setpoint, Target — assign the Temperature system tag combined with a custom qualifier tag to each datastream.

• A device with sensors across multiple zones — combine a measurement system tag with a custom zone qualifier tag per datastream.

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Conflicts

Duplicate tag combinations

The same individual tag can be assigned to multiple datastreams in a template, unless the tag is marked as single per template in the reference table below. What must remain unique is the combination of tags on each datastream — no two datastreams in the same template can have an identical set of Semantic Tags.

A conflict can occur when you remove a tag from a datastream, causing its remaining tag combination to match another datastream's combination in the same template. When this happens, an inline error is shown and you cannot save the datastream until the conflict is resolved.

Deleting a tag that is in use

The behavior when deleting a Semantic Tag depends on how it is currently used:

• Not used, or used in only one datastream — the tag can be deleted freely.

• Used in a datastream in the same template — the warning appears.

• Used in datastreams across multiple templates — the warning appears.

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Where Semantic Tags are used

Once assigned, Semantic Tags affect several areas of the product. See the dedicated sub-page for full details:

• Using Semantic Tags

Quick overview:

Area	How Semantics are used
Automations	Allows selecting datastreams by semantic group instead of by name/pin when configuring Control Segment actions
Dashboard Widgets	Datastream picker offers a "Property Group (Semantics)" view in addition to the standard pin picker
Column Management	Device list columns can be bound to a Semantic Group rather than a specific datastream name
Developer Tools	Uptime, Free Memory, Mode Display, Battery Level, and MAC Address panels are driven by their respective System Tags
Dashboard Widgets	Devices can be filtered by datastream value via a semantic-aware cascader picker

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Semantic Tag reference

The tables below list all available System Tags grouped by category.

Single per template (✅) means the tag can be assigned to at most one datastream per template. All other System Tags can be used across multiple datastreams, but the combination of tags on each datastream must be unique within the template.

State

Display Name	Value Type	Unit	Supported Value Types	Single per Template
Automation Scenario JSON	STRING	—	STRING	✅
Automation Status	INT	—	STRING, INT, BOOL, ENUM	✅
Error Code	STRING	—	INT, STRING, ENUM
Free Memory	DOUBLE	Kilobytes	INT, DOUBLE	✅
Last Seen Timestamp	STRING	—	STRING	✅
Mode Display	ENUM	—	STRING, ENUM, INT
Operating State	STRING	—	STRING, ENUM, INT
Sensor Status	STRING	—	STRING, ENUM, INT
Status	STRING	—	STRING, ENUM
Uptime	INT	Seconds	INT	✅

Sensor

Display Name	Value Type	Unit	Supported Value Types	Single per Template
Air Pollution	DOUBLE	AQI	DOUBLE, INT
Air Pressure	DOUBLE	Hectopascal	DOUBLE, INT
Altitude	DOUBLE	Meters	DOUBLE, INT
Ambient Light	DOUBLE	Lux	DOUBLE, INT
Battery Capacity	DOUBLE	Milliampere	DOUBLE, INT
Battery Level	INT	Percent	DOUBLE, INT
CO₂	DOUBLE	Particles per million	DOUBLE, INT
CPU Temperature	DOUBLE	Celsius	DOUBLE, INT
CPU Temperature	DOUBLE	Fahrenheit	DOUBLE, INT
Current	DOUBLE	Ampere	DOUBLE, INT
Distance / Proximity	DOUBLE	Centimeter	DOUBLE, INT
Energy Consumption	DOUBLE	Kilowatt Hour	DOUBLE, INT
Fill Level	INT	Percent	DOUBLE, INT
Flow Rate	DOUBLE	Liter per second	DOUBLE, INT
GPS Coordinates	GPS	—	GPS
Humidity	INT	Percent	DOUBLE, INT
Noise Level	DOUBLE	Decibel	DOUBLE, INT
PH	DOUBLE	pH	DOUBLE, INT
Power	DOUBLE	Watt	DOUBLE, INT
Pressure (generic)	DOUBLE	Pascal	DOUBLE, INT
Pulse Counter	INT	—	DOUBLE, INT
Soil Moisture	INT	Percent	DOUBLE, INT
Speed	DOUBLE	Kilometer per hour	DOUBLE, INT
Temperature	DOUBLE	Celsius	DOUBLE, INT
Temperature	DOUBLE	Fahrenheit	DOUBLE, INT
Total Consumption / Counter	DOUBLE	—	DOUBLE, INT
Vibration	DOUBLE	Meter per second	DOUBLE, INT
Voltage	DOUBLE	Volt	DOUBLE, INT
Volume	DOUBLE	Liter	DOUBLE, INT
Water Leak / Water Presence	INT	—	DOUBLE, INT

Network

Display Name	Value Type	Unit	Supported Value Types	Single per Template
Cellular Network Name (Operator)	STRING	—	STRING, ENUM	✅
Cellular Signal Quality	INT	Percent	DOUBLE, INT	✅
Cellular Signal Strength	DOUBLE	Signal Strength	DOUBLE, INT	✅
Connection Status	STRING	—	STRING, ENUM	✅
IP Address	STRING	—	STRING	✅
LTE Metrics (RSRP, RSRQ, SINR)	STRING	—	INT, DOUBLE, STRING
MAC Address	STRING	—	STRING	✅
WiFi Network Name (SSID)	STRING	—	STRING	✅
WiFi Signal Quality	INT	Percent	DOUBLE, INT	✅
WiFi Signal Strength (RSSI)	DOUBLE	Signal Strength	DOUBLE, INT	✅

Control

Display Name	Value Type	Unit	Supported Value Types	Single per Template
Automation Control (on/off)	INT	—	BOOL, INT	✅
Brightness	INT	Percent	DOUBLE, INT
Color	STRING	—	STRING
Fan Speed	INT	Percent	DOUBLE, INT
LED	INT	—	DOUBLE, INT
Mode Selector	ENUM	—	STRING, ENUM, INT
Output Level (0–100%)	INT	Percent	DOUBLE, INT
Power Switch	INT	—	INT, BOOL
Range (0–X)	INT	Percent	DOUBLE, INT
Reboot	INT	—	INT, BOOL
Servo / Motor Position	INT	Degree	DOUBLE, INT
Switch	INT	—	INT, BOOL
Target Humidity	INT	Percent	DOUBLE, INT
Target Temperature	DOUBLE	Celsius	DOUBLE, INT
Target Temperature	DOUBLE	Fahrenheit	DOUBLE, INT
Valve Position	INT	Percent	DOUBLE, INT

Other

Display Name	Value Type	Unit	Supported Value Types	Single per Template
Debug Commands	STRING	—	STRING	✅
Device Type	STRING	—	STRING, ENUM	✅
Firmware Version	STRING	—	INT, DOUBLE, STRING
Label	STRING	—	STRING, ENUM
Measurement System	ENUM	—	STRING, ENUM	✅
Timezone	STRING	—	STRING, ENUM	✅

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Limits and constraints

Constraint	Details
System Tags per datastream	1
Custom Tags per datastream	Up to 4
Total tags per datastream	Up to 5 (1 system + 4 custom)
Tag combination uniqueness	Each datastream's tag combination must be unique within the template
Single-per-template System Tags	Some System Tags (marked ✅ above) can only be assigned to one datastream per template

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Related

• Where Semantic Tags are used

• Datastreams