Computed Sensors
Define custom telemetry calculations using JavaScript expressions with a live testing playground.
Last updated April 17, 2026
The Sensors module enables per-vehicle computed metrics. Each sensor runs a JavaScript expression against raw telemetry attributes from the GPS device, producing a derived value (fuel level, temperature, battery voltage, etc.).
Creating a Sensor
- Navigate to Vehicles > select a vehicle > Sensors tab
- Click Add New Sensor
- Enter Name (e.g., "Fuel Level") and Unit (e.g., "liters")
- Select an Icon from the gallery
- Write a JavaScript expression in the code editor, or choose a pre-built Template
- Click Run to test against live telemetry or a sample payload
- Review the result in the Preview panel
- Click Save
Sensor Fields
| Field | Required | Description |
|---|---|---|
| Name | Yes | Display name |
| Unit | No | Measurement unit (liters, °C, %, V) |
| Icon | No | Display icon from searchable gallery |
| Code | Yes | JavaScript expression for computation |
Playground
The built-in playground lets you test sensor expressions before saving:
- Live Telemetry panel — view raw device attributes
- Insert button — add attribute names directly into code
- Sample Payload — editable JSON for testing edge cases
- Run button — execute expression and show result
- Templates — pre-built formulas for fuel level, temperature, battery voltage
Example Expressions
javascript
// Fuel level from analog input
var raw = attributes.adc1 || 0;
var fuel = (raw - 100) * 0.5;
Math.max(0, Math.min(fuel, 100));javascript
// Battery voltage (mV to V)
(attributes.battery || 0) / 1000;Sensor Status
| Status | Meaning | Action |
|---|---|---|
| OK | Expression computes successfully | No action needed |
| Error | Expression failed | Check attribute names, syntax, and handle missing values with || 0 |
| N/A | No data available yet | Wait for next device telemetry packet |
Tip
Start with a simple expression like 42 to verify the sensor framework works, then build up your actual formula.