Shelly Plus Add-On

Shelly Plus Add-On — Isolated Sensor Interface for Shelly Plus Relays

The Shelly Plus Add-On is a galvanically isolated sensor interface designed for Shelly Plus relays. It expands their measurement capabilities with up to 5 DS18B20 temperature sensors, a DHT22 temperature and humidity sensor, analog and digital inputs, and NTC sensors. No hub or additional subscriptions.

Technical Specifications — Shelly Plus Add-On

• Interface: Proprietary Shelly Serial (direct connection to Plus/Pro relays)
• Isolation: Galvanic
• 1-Wire Sensors (DS18B20): Up to 5 simultaneous sensors
• DHT22 Sensor: Temperature + Humidity (1 sensor)
• NTC: 10 kΩ resistors (β=4000 K coefficient)
• Analog Input: 0–10 V (light, gas, soil moisture sensors, etc.)
• Digital Input: Yes
• Operating Temperature: -20 to +40°C
• Certifications: CE, RoHS

Compatible Sensors

• Up to 5 DS18B20 sensors (temperature, 1-Wire)
• 1 DHT22 sensor (temperature + humidity)
• NTC 10 kΩ resistors
• Photoresistors (LDR)
• PIR sensors
• Soil moisture sensors
• Ultrasonic proximity sensors
• Capacitive liquid detectors
• Other analog sensors with 0–10 V output

Compatible with

• Shelly Plus 1, Plus 1PM, Plus 2PM and other relays in the Plus range
• Home Assistant (local, no cloud)
• Amazon Alexa and Google Home (via the Shelly Plus relay)
• MQTT, HTTP REST API, mJS Scripting

Use cases

• Automated irrigation based on soil moisture: activates the relay only when necessary
• Lighting control via photoresistor: turns on when dark according to ambient light
• Temperature monitoring in aquariums, cellars, or server rooms
• Automatic awning closing with a wind sensor connected to the analog input

Official Shelly distribution. Shipping from Spain. Official Shelly warranty.