> For the complete documentation index, see [llms.txt](https://docs.blynk.io/en/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.blynk.io/en/blynk.console/templates/datastreams/semantic-tags.md).
# 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
***
### 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.
***
### 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**.
{% hint style="info" %}
**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.
{% endhint %}
***
### 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
{% hint style="success" %}
**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.
{% endhint %}
***
### 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.
***
### 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.
***
### 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.
***
### 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](https://docs.blynk.io/en/blynk.console/templates/datastreams/semantic-tags/where-semantic-tags-are-used)
**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 |
***
### 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 | ✅ |
***
### 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 |
***
### Related
* [Where Semantic Tags are used](https://docs.blynk.io/en/blynk.console/templates/datastreams/semantic-tags/where-semantic-tags-are-used)
* [Datastreams](https://docs.blynk.io/en/blynk.console/templates/datastreams)
---
# Agent Instructions
This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com.
## Querying This Documentation
If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.
Perform an HTTP GET request on the current page URL with the `ask` query parameter, and the optional `goal` query parameter:
```
GET https://docs.blynk.io/en/blynk.console/templates/datastreams/semantic-tags.md?ask=&goal=
```
`ask` is the immediate question: it should be specific, self-contained, and written in natural language.
`goal` is optional and describes the broader end goal you are ultimately trying to accomplish on behalf of the user. GitBook uses it to tailor the answer towards what is most useful for that goal.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.
Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.