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Mounting the Milesight EM300 Temperature & Humidity Sensor

This article explains how to physically install and mount a Milesight EM300 Temperature and Humidity Sensor, to ensure accurate environmental monitoring for refrigerated assets, cold rooms, trailers, and storage containers.

Overview

The Milesight EM300 is a compact, battery-powered wireless environmental sensor designed to monitor temperature, relative humidity.
It communicates over LoRaWAN to a compatible gateway (such as the Milesight UG65), enabling cold-chain compliance, door activity auditing, and alerting within IoT platforms.

Product references:

Key capabilities:

  • Temperature and humidity monitoring

  • Wireless LoRaWAN communication

  • Long battery life

  • Compact, rugged housing

What’s in the Box

Confirm the following components before installation:

  • Milesight EM300 sensor module

  • Screws and anchors (where supplied)

  • Quick Start Guide with Device EUI / Serial Number

Tools and Materials

Tools

  • Screwdriver

  • Drill and drill bits

  • Spirit level (optional)

Materials

  • Screws and anchors suitable for metal or insulated panels

  • Cable ties or adhesive cable clips

  • Split-loom tubing for protecting sensor cables

  • Industrial adhesive pads (optional)

Safety and Pre-Installation Considerations

Before mounting:

  • Ensure installation does not interfere with seals or insulation

  • Avoid drilling through refrigeration lines or wiring 

Mounting the EM300 Sensor

1. Choose the Mounting Location

Select a location that supports accurate temperature/humidity measurement and reliable LoRaWAN communication:

Indoor Areas

  • Height roughly at environmental mid-plane (not too low near floor, not too high near ceiling)

  • Away from direct HVAC vents or obstructions

Cold-Chain Compartments

  • Place sensor where air circulation reflects bulk cargo temperature

  • Avoid direct airflow near evaporator vents that can bias readings

General guidelines:

  • Keep sensor at breathing height (1.0–1.5 m) for general indoor environments

  • Place critical cold-chain probes closer to middle of the compartment, not against walls

2. Prepare the Mounting Surface

Before attaching the sensor:

  1. Clean the surface to remove dust/oil.

  2. Mark two hole locations using the mounting bracket as a template.

  3. Use a spirit level if precise alignment is required for aesthetics.

3. Attach the Mounting Plate or Bracket

Depending on your kit:

A. Screw Mounting (Preferred)

  1. Drill pilot holes at marked points.

  2. Insert anchors into hollow block or drywall if necessary.

  3. Secure the mounting base with screws.

  4. Confirm that it is solid and will not twist under small forces.

B. Adhesive Mounting (Optional)

  1. Use industrial-strength adhesive pads suitable for environmental conditions.

  2. Apply pad to the sensor mounting base.

  3. Firmly press against surface.

  4. Allow recommended cure time before finalizing placement.

Note: Adhesive mounting is suitable for temporary or enclosed environments with low vibration.

4. Attach the Sensor Module

  1. Once the base or bracket is secured, align the EM300 sensor body.

  2. Snap or secure the sensor to the bracket.

  3. Ensure the sensor is oriented so its air intake vents are unobstructed.

Verifying Operation

LoRa Sensor Connectivity

Once the gateway is online and commissioned:

Open Perspio and:

  • Check that sensor nodes begin to register and report through the gateway

  • Validate that LoRa packets are being received by the gateway

  • Confirm uplink frequency usage is within compliance for your region

Sensor Health Checks

Measurement Validation

  • Ensure that readings are within expected ranges for the environment.

  • If values appear out-of-range, verify sensor location (not near vents) and confirm battery and communication status.

Uplink Frequency

Typical LoRaWAN sensors report at configured intervals (e.g., every 5, 10, or 30 minutes):

  • Confirm that uplinks appear at your configured reporting cadence.

  • Review gateway statistics to ensure packets are received and forwarded successfully.

Best-Practice Deployment Tips

  • Place sensors in representative positions (not corners or isolated spots).

  • Avoid mounting near reflective metal surfaces that can distort readings or attenuate RF.

  • Position external probes away from heat sources that skew temperature measurements.

  • Provide occasional access for sensor battery replacement or manual checks.

Best-Practice Deployment Tips

  • Avoid routing cable near heaters or sharp edges

  • Use protective loom where vibration is present

  • Recheck alignment after first 24 hours of operation

Common Issues and Troubleshooting

No Data Appearing in Platform

  • Confirm LoRaWAN gateway is online and associated with your network server.

  • Check sensor provisioning (Device EUI, OTAA keys, correct network plan).

  • Verify no coverage or signal attenuation between sensor and gateway.

Erratic Readings

  • Ensure the sensor is not mounted too close to vents, doors, or HVAC intakes.

  • Allow the environment to stabilise for a few hours for representative readings.

Uplinks Not Received

  • Confirm region frequency plan matches gateway/LoRaWAN server settings.

  • Reposition sensor to improve LoRa signal coverage.

Manufacturer References

Summary

The Milesight EM300 Temperature and Humidity Sensor is a reliable LoRaWAN environmental sensor suited for cold-chain monitoring and general environmental telemetry. Correct physical mounting — including optimal placement for representative measurement, secure bracket installation, and proper antenna/gateway connectivity — ensures accurate environmental data flow into Perspio. Once commissioned and joined to a LoRaWAN network with a compatible gateway, the EM300 reliably reports temperature and humidity data, enabling alerts, analytics, and reporting.