Milesight EM300-TH: LoRaWAN Temperature & Humidity Sensor

Milesight EM300-TH LoRaWAN temperature & humidity sensor: own ChirpStack/ThingsBoard decoder, decoded example, threshold alerts and cold-chain integration.

EM300-THSensor

LoRaWAN: Class A, OTAA
Band / port: EU868 / port 85
Ingress protection: IP67
Temperature: -30 to +70 °C (SHT30)
Humidity: 0 to 100 % RH
Battery: 4000 mAh, several years
Configuration: NFC (Milesight ToolBox)

Measurements

What the EM300-TH measures

Temperature

Sensirion SHT30, -30 to +70 °C, high accuracy.

Humidity

Relative humidity 0 to 100 % RH (non-condensing).

Battery level

Reported every 6 hours, with local storage and retransmission.

Data into your dashboard

Integration

Sensor / controller

Measures or controls in the field and sends LoRaWAN uplinks.

LoRaWAN gateway

Receives the radio packets and forwards them to the server.

ChirpStack

Network server: manages sessions and decodes the payload.

ThingsBoard / Grafana

Dashboards, alarms, rules and reports.

ChirpStack Payload Decoder ChirpStack → ThingsBoard

ChirpStack v4 · decodeUplink

function decodeUplink(input) {
  var bytes = input.bytes;
  var data = {};

  for (var i = 0; i < bytes.length; ) {
    var channel = bytes[i++];
    var type = bytes[i++];

    if (channel === 0x01 && type === 0x75) {          // battery (%)
      data.battery = bytes[i]; i += 1;
    } else if (channel === 0x03 && type === 0x67) {   // temperature (°C)
      data.temperature = readInt16LE(bytes, i) / 10; i += 2;
    } else if (channel === 0x04 && type === 0x68) {   // humidity (%RH)
      data.humidity = bytes[i] / 2; i += 1;
    } else {
      break;
    }
  }
  return { data: data };
}

function readInt16LE(b, i) {
  var v = (b[i + 1] << 8) | b[i];
  return v > 0x7fff ? v - 0x10000 : v;
}

Implemented from the published Milesight byte specification (Communication Protocol / User Guide).

Channel format: 01 75 battery (%), 03 67 temperature (INT16 little-endian, /10), 04 68 humidity (/2). Uplinks without a battery channel are normal, the battery is only reported every six hours. For ThingsBoard the same logic goes into an uplink converter.

Uplink (hex)

0175640367AD00046873

Decoded JSON

{ "battery": 100, "temperature": 17.3, "humidity": 57.5 }

Where it fits

Use cases

Cold-chain monitoring

HACCP-compliant temperature logs with threshold alarms.

Smart office & buildings

Comfort and humidity tracking across offices and rooms.

Server room & archive

Climate monitoring of critical rooms with instant alerts.

From the field

Configuration & pitfalls

NFC setup

Keys, reporting interval and threshold alarms are set over NFC with the Milesight ToolBox before rollout.

Threshold alarms

Sent immediately, outside the reporting interval. Dashboard rules should treat alarm uplinks as priority events.

Calibration

The device adds a calibration offset to the raw value. Document the offset so dashboard readings stay traceable.

IP67 venting lag

The sealed IP67 enclosure equalises air through a vent membrane, so after a large temperature jump it can take around an hour until the sensor settles on the true value. Account for this when alerting on fast transitions.

D2D

The EM300-TH can trigger another Milesight device (e.g. a relay) directly without a gateway, useful for local fail-safes.

Your partner

How merkaio supports your EM300-TH

From sourcing to day-to-day operation, all from one partner on our own European infrastructure.

Pre-staging & provisioning

We configure the EM300-TH, set keys, intervals and alarms, and ship it ready to deploy.

Own decoder

Payload codec for ChirpStack v4 and ThingsBoard, implemented from the Milesight specification.

Dashboard integration

Data lands in your ThingsBoard or Grafana, with alarms and reports.

Operations & monitoring

We run the LoRaWAN stack and dashboards on European infrastructure, you just use the data.

Discuss your project

Frequently asked questions

Yes. It is a standard LoRaWAN device, no Milesight gateway or cloud required. You add the codec to the device profile and provision it via OTAA.

Yes, for both ChirpStack and ThingsBoard, implemented from the published Milesight byte specification. The same channel logic goes into a ThingsBoard uplink converter.

It is a Class A device on LoRaWAN port 85. Each uplink carries temperature and humidity; the battery level is reported every six hours.

Yes. The enclosure is rated IP67 and the operating range is -30 to +70 °C, so it suits both indoor rooms and outdoor or refrigerated environments.

It ships with a replaceable 4000 mAh battery that lasts several years, depending on the reporting interval you configure.

Yes. Thresholds are set over NFC with the Milesight ToolBox and are sent immediately, outside the regular reporting interval, so dashboard rules should treat alarm uplinks as priority events.

From the same series

Related devices

EM300-SLD EM320-TH AM307

Let's discuss your infrastructure. Digital and on-site.

Whether it's IoT platform development, hardware selection, managed hosting for ChirpStack, ThingsBoard, Grafana or NetBird VPN, or migration from a self-hosted setup - we'll find the right solution for your use case. Book a free 30-minute consultation, no commitment required.

Your contact

Timo Wevelsiep

Founder, merkaio

15 minutes, no commitment, directly with Timo.

[email protected]

Decoder for ChirpStack v4. merkaio is an independent integrator and is not affiliated with Milesight.