Table of Contents:

1.  Introduction

1.1 ​ What is LMDS120 Microwave Radar Distance Sensor

The Dragino LMDS120 is a LoRaWAN Microwave Radar distance sensor. It uses use Microwave Radar to detect the distance between sensor and different objects. Different from ultrosonic or Lidar measurement. Microwave Radar is more reliable for condensation / dusty environment. It can sense correct distance even there is water or think dust on top of the sensor.

The LMDS120 can be applied to scenarios such as horizontal distance measurement, parking management system, object proximity and presence detection, intelligent trash can management system, robot obstacle avoidance, automatic control, sewer, etc.

The LoRa wireless technology used in LMDS120 allows device to send data and reach extremely long ranges at low data-rates. It provides ultra-long range spread spectrum communication and high interference immunity whilst minimizing current consumption.

LMDS120 is powered by 8500mAh Li-SOCI2 battery, it is designed for long term use up to 5 years.

Each LMDS120 is pre-load with a set of unique keys for LoRaWAN registrations, register these keys to local LoRaWAN server and it will auto connect after power on.


​1.2  Features

  • LoRaWAN 1.0.3 Class A
  • Ultra-low power consumption
  • 60Ghz Microwave Radar for distance detection
  • Monitor Battery Level
  • Bands: CN470/EU433/KR920/US915/EU868/AS923/AU915/IN865
  • AT Commands to change parameters
  • Uplink on periodically
  • Downlink to change configure
  • 8500mAh Battery for long term use
  • Wall Mountable
  • Outdoor Use

1.3  Radar probe specification

  • Measuring Method: FMCW
  • Frequency: 60 GHz
  • Measure Range : 15 ~ 1200cm
  • Accuracy: ±(2cm+SX0.3%). S: Measure Value
  • Resolution: 1cm
  • Measurement Angle : 25 degrees horizontal and 23 degrees vertical

1.4  Storage & Operation Temperature

-15°C to +65°C

1.5 ​ Applications

  • Horizontal distance measurement
  • Liquid level measurement
  • Parking management system
  • Object proximity and presence detection
  • Intelligent trash can management system
  • Robot obstacle avoidance
  • Automatic control
  • Sewer
  • Bottom water level monitoring

1.6  Pin mapping and power on



2.  Operation Mode

2.1  How it works

Each LMDS120 is shipped with a worldwide unique set of OTAA keys. To use LMDS120 in a LoRaWAN network, user needs to input the OTAA keys in the LoRaWAN network server. So LMDS120 can join the LoRaWAN network and start to transmit sensor data.

2.2  ​Example to use for LoRaWAN network

Following is an example for how to join the TTN v3 LoRaWAN Network. Below is the network structure; we use the DLOS8  as a LoRaWAN gateway in this example. 


  • In this user case, the LMDS120 is installed on top of river to detect the water level and send the level info to the LoRaWAN server. The LMDS120 will uplink different types of messages to the LoRaWAN server. See Uplink payload for detail.

Assume the LoRaWAN Gateway DLOS8 is already set to connect to the TTN V3 network . We need to add the LMDS120 device in TTN V3:


Step 1: Create a device in TTN with the OTAA keys from LMDS120.

Each LMDS120 is shipped with a sticker with the default device keys, user can find this sticker in the box. it looks like below.



Users can enter these keys in the LoRaWAN Server portal. Below is the TTN V3 screenshot:

Add APP EUI in the application.





You can also choose to create the device manually.




Step 2:  Power on LMDS120

Put a Jumper on JP2 to power on the device. ( The Switch must be in FLASH position).


Put the jumper to power on LMDS120 and it will auto-join to the TTN V3 network. After join success, it will start to upload sensor data to TTN V3 and the user can see it in the panel.

2.3  ​Uplink Payload

Uplink payloads have two types:

  • Distance Value: Use FPORT=2
  • Other control commands: Use other FPORT fields.

The application server should parse the correct value based on FPORT settings.

2.3.1  Device Status, FPORT=5

Include device configure status. Once LMDS120 Joined the network, it will uplink this message to the server.

Users can also use the downlink command (0x26 01) to ask LMDS120 to resend Device Status.

Device Status (FPORT=5)
ValueSensor ModelFirmware VersionFrequency BandSub-band


  • Sensor Model: For LMDS120, this value is 0x18
  • Firmware Version: 0x0100, Means: v1.0.0 version
  • Frequency Band:

0x01: EU868

0x02: US915

0x03: IN865

0x04: AU915

0x05: KZ865

0x06: RU864

0x07: AS923

0x08: AS923-1

0x09: AS923-2

0x0a: AS923-3

0x0b: AS923-4

  • Sub-Band:
    • AU915 and US915:value 0x00 ~ 0x08
    • CN470: value 0x0B ~ 0x0C
    • Other Bands: Always 0x00

2.3.2  Distance, Uplink FPORT=2

LMDS120 will send this uplink after Device Status once join the LoRaWAN network successfully. And LMDS120 will:

  1. periodically send this uplink every 20 minute (TDC time), this interval can be changed.
  2. send this uplink while there is interrupt event.

Uplink Payload totals 8 bytes.

Distance Value, FPORT=2
ValueBATDistanceinterruptDS18B20 temperatureSensor flag



Distance between sensor probe to the first object.  (unit: mm)

For example, if the data you get from the register is 0x0D 0xC6, the distance between the sensor and the measured object is 0DC6(H) = 3526 (D) = 3526 mm.

Notice: The distance has a special value :

0x3FFF: Reading Invalid (exceed the valid range of the probe) or Probe not detected.

2.3.3  Decoder in TTN V3


Please check the decoder from this link:

2.4  ​Show data on Datacake

Datacake IoT platform provides a human-friendly interface to show the sensor data, once we have sensor data in TTN V3, we can use Datacake to connect to TTN V3 and see the data in Datacake. Below are the steps:


Step 1Link TTNv3 to DATACAKE

Step 2Configure LMDS120 in Datacake










3.  Configure LMDS120 via AT Command or LoRaWAN Downlink

Use can configure LMDS120 via AT Command or LoRaWAN Downlink.


There are two kinds of commands to configure LMDS120, they are:

  •  General Commands.

These commands are to configure:

  • General system settings like: uplink interval.

  • LoRaWAN protocol & radio related command.

They are same for all Dragino Device which support DLWS-005 LoRaWAN Stack(Note**). These commands can be found on the wiki: End Device AT Commands and Downlink Command


  •  Commands special design for LMDS120

These commands only valid for LMDS120, as below:

3.1  Set Transmit Interval Time(0x01)

Feature: Change LoRaWAN End Node Transmit Interval.

AT Command: AT+TDC

Command ExampleFunctionResponse
AT+TDC=?Show current transmit Interval

the interval is 30000ms = 30s

AT+TDC=60000Set Transmit Interval

Set transmit interval to 60000ms = 60 seconds

Downlink Command: 0x01

Format: Command Code (0x01) followed by 3 bytes time value.

If the downlink payload=0100003C, it means set the END Node's Transmit Interval to 0x00003C=60(S), while type code is 01.

Example 1: Downlink Payload: 0100001E        //  Set Transmit Interval (TDC) = 30 seconds

Example 2: Downlink Payload: 0100003C       //  Set Transmit Interval (TDC) = 60 seconds

3.2  Set Interrupt Mode(0x06)

Feature, Set Interrupt mode for GPIO_EXIT.

Downlink Command: AT+INTMOD

Command ExampleFunctionResponse
AT+INTMOD=?Show current interrupt mode

the mode is 0 = No interruption


Set Transmit Interval
1. (Disable Interrupt),
2. (Trigger by rising and falling edge)
3. (Trigger by falling edge)
4. (Trigger by rising edge)


Downlink Command: 0x06

Format: Command Code (0x06) followed by 3 bytes.

This means that the interrupt mode of the end node is set to 0x000003=3 (rising edge trigger), and the type code is 06.

Example 1: Downlink Payload: 06000000           // Turn off interrupt mode

Example 2: Downlink Payload: 06000003           // Set the interrupt mode to rising edge trigger

4.  Battery & Power Consumption

LMDS120 uses ER26500 + SPC1520 battery pack. See below link for detail information about the battery info and how to replace.

Battery Info & Power Consumption Analyze .

5.  FAQ

5.1  How to use AT Command to configure LMDS120

LMDS120 UART connection photo


LMDS120 supports AT Command set. User can use a USB to TTL adapter plus the 3.5mm Program Cable to connect to LMDS120 to use AT command, as below.


In the PC, you need to set the serial baud rate to 9600 to access the serial console for LMDS120. LMDS120 will output system info once power on as below:


5.2  How to upgrade the firmware?

A new firmware might be available for:

  • Support new features

  • For bug fix

  • Change LoRaWAN bands.

5.3  How to change the LoRa Frequency Bands/Region

You can follow the instructions for how to upgrade image.
When downloading the images, choose the required image file for download. ​

6.  Trouble Shooting

6.1  AT Command input doesn't work

In the case if user can see the console output but can't type input to the device. Please check if you already include the ENTER while sending out the command. Some serial tool doesn't send ENTER while press the send key, user need to add ENTER in their string. 

7.  Order Info

Part Number : LMDS120-XX

XXThe default frequency band

  • AS923 : LoRaWAN AS923 band
  • AU915 : LoRaWAN AU915 band
  • EU433 : LoRaWAN EU433 band
  • EU868 : LoRaWAN EU868 band
  • KR920 : LoRaWAN KR920 band
  • US915 : LoRaWAN US915 band
  • IN865 :  LoRaWAN IN865 band
  • CN470 : LoRaWAN CN470 band

8. ​ Packing Info

Package Includes:

  • LMDS120 LoRaWAN Microwave Radar Distance Sensor x 1

9.  ​Support

  • Support is provided Monday to Friday, from 09:00 to 18:00 GMT+8. Due to different timezones we cannot offer live support. However, your questions will be answered as soon as possible in the before-mentioned schedule.
  • Provide as much information as possible regarding your enquiry (product models, accurately describe your problem and steps to replicate it etc) and send a mail to
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