---
title: Mounting the Milesight EM300 MCS Temperature & Humidity Sensor
description: Install and verify the MileSight EM300 MCS (door sensor) for temperature and humidity monitoring in Perspio.
---
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# Mounting the Milesight EM300 MCS Temperature & Humidity Sensor
## This article explains how to physically install and mount a Milesight EM300 Temperature and Humidity Sensor, including the MCS magnetic door sensor, to ensure accurate environmental monitoring and door open/close detection 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**, and—when paired with the **MCS magnetic door sensor**—**door open/close status**.
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:
- [**Milesight EM300 MCS Product Page**](https://www.milesight.com/products/em300-mcs/)
- [**Milesight Support & Downloads**](https://www.milesight.com/support)
Key capabilities:
- Temperature and humidity monitoring
- Door open / close detection via magnetic contact (MCS sensor)
- Wireless LoRaWAN communication
- Long battery life
- Compact, rugged housing
---
#### What’s in the Box
Confirm the following components before installation:
- **Milesight EM300 sensor module**
- **MCS magnetic door sensor cable**
(two-piece magnetic contact: sensor lead + magnet)
- Mounting plate or clip
- 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 door seals or insulation
- Avoid drilling through refrigeration lines or wiring
- Confirm door movement path (swing or slide)
- Plan cable routing so the door opens freely without tension on the sensor cable
---
#### Mounting the EM300 Sensor
### 1. Choose the Mounting Location
The EM300 main unit should be mounted:
- Inside the refrigerated compartment or cold room
- Away from evaporator fans or direct cold air blast
- At a representative height where air temperature reflects cargo temperature
Recommended:
- Mid-height on an interior wall
- Not directly against metal evaporator housings
---
### 2. Prepare the Mounting Surface
1. Clean the surface to remove moisture or grease.
2. Mark the mounting holes using the bracket as a template.
3. Ensure adequate clearance for the sensor body and cable exit.
---
### 3. Attach the Mounting Plate
Secure the mounting plate using screws (preferred):
1. Drill pilot holes if required.
2. Install anchors where necessary.
3. Fasten the plate securely so it does not vibrate or loosen.
---
### 4. Attach the EM300 Sensor Module
1. Align the sensor body with the mounting plate.
2. Clip or slide the sensor into place.
3. Ensure air vents are unobstructed for accurate readings.
---
#### Installing the **MCS Magnetic Door Sensor**
The **MCS sensor** is a **magnetic reed switch** used to detect when a refrigerated door is **open or closed**.
It consists of **two parts**:
- **Sensor lead (wired)** – connected to the EM300
- **Magnet (passive)** – mounted on the moving door
When the magnet and sensor are **touching or very close**, the door is considered **closed**.
When they **separate**, the door is considered **open**.
---
### 5. Mount the MCS Sensor Lead (Fixed Side)
1. Mount the **wired sensor lead** on the **fixed frame** of the refrigerated unit.
2. Use screws or industrial adhesive.
3. Ensure the cable exits cleanly without sharp bends.
4. Secure the cable with clips or cable ties to prevent strain.
Best practice:
- Mount on the door frame, not on flexible insulation
- Keep cable slack to absorb vibration
---
### 6. Mount the Magnet (Door Side)
1. Mount the **magnet** on the **moving door panel**.
2. Align it directly with the sensor lead.
3. When the door is fully closed, the two parts must:
- Touch, or
- Be within **5–10 mm** (manufacturer tolerance)
Important:
- The magnet must move away from the sensor when the door opens
- Do not mount on compressible rubber seals
---
### 7. Alignment Check
Before finalising installation:
1. Slowly open and close the door.
2. Observe that:
- Door closed → magnet touches sensor
- Door open → magnet separates cleanly
3. Adjust alignment if required.
Incorrect alignment will cause:
- False door open alarms
- Missed door activity events.
---
#### 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
### Door Status Validation
Once connected to the LoRaWAN network and visible in Perspio:
- Closed door → **Door Status = Closed**
- Open door → **Door Status = Open**
Validate by manually opening and closing the door and confirming state changes.
---
### Sensor Health Checks
- Ensure the Sensor last activity timestamp is recent (usually every 10 minutes)
- Review LoRa statistics (packets received, gateways seen, etc.) in your network management
---
#### Best-Practice Deployment Tips
- Do not stretch the MCS cable across moving joints
- 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
**Door Always Showing Open**
- Magnet not aligned correctly
- Gap too large when door is closed
- Magnet mounted on flexible surface
**Intermittent Door Events**
- Loose mounting
- Cable under tension
- Door vibration causing separation
**No Door Events at All**
- Sensor lead not connected
- Incorrect sensor variant
- Device not joined to LoRaWAN network
---
#### Manufacturer References
- [**Milesight EM300 MCS Product Page**](https://www.milesight.com/products/em300-mcs)
- [**Milesight Support & Technical Documentation**](https://www.milesight.com/support)
---
#### Summary
The **Milesight EM300 with MCS magnetic door sensor** provides reliable **temperature, humidity, and door open/close monitoring** for refrigerated assets. Correct physical installation—especially **precise alignment of the magnetic door sensor**—is critical to ensure accurate door state detection and cold-chain compliance. When properly mounted and commissioned, the EM300 delivers dependable environmental and door activity data for alerts, reporting, and operational insights.
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