Table of Contents:

1.  Introduction

1.1 ​ What is NMDS200 NB-IoT Microwave Radar Distance Sensor

The Dragino NMDS200 is a NB-IoT Microwave Radar distance sensor. It uses 24Ghz Microwave to detect the distance between sensor and different objects. Compare vs ultrasonic or Lidar measurement method, Microwave Radar is more reliable for condensation / dusty environment. It can sense correct distance even there is water or thick dust on top of the sensor.

The NMDS200 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.

NMDS200 can measure two distances: the closest object and next object behind the closest one.

NMDS200 supports Alarm Feature, user can set the NMDS200 to uplink data in a short interval when the distance is out of configured range.

NarrowBand-Internet of Things (NB-IoT) is a standards-based low power wide area (LPWA) technology developed to enable a wide range of new IoT devices and services. NB-IoT significantly improves the power consumption of user devices, system capacity, and spectrum efficiency, especially in deep coverage.

NMDS200  supports different uplink methods including TCP, MQTT, UDP, and CoAP for different application requirements.

NMDS200 is powered by 8500mAh Li-SOCI2 battery, It is designed for long-term use of up to 5 years. (Actually Battery life depends on the use environment, update period & uplink method)

To use NMDS200, user needs to check if there is NB-IoT coverage in the field and with the Nb-IoT bands that NMDS200 supports. If local operator support it, user needs to get a NB-IoT SIM card from the operator and install into NMDS200 to get NB-IoT network connection.

​1.2  Features

  • NB-IoT Bands: B1/B3/B8/B5/B20/B28 @H-FDD
  • Short uplink interval for Distance Alarm
  • Monitor Battery Level
  • Microwave Radar for distance detection
  • Datalog feature
  • Uplink periodically
  • Downlink to change configure
  • Wall Mountable
  • Outdoor Use
  • Ultra-Low Power consumption
  • AT Commands to change parameters
  • Micro SIM card slot for NB-IoT SIM
  • 8500mAh Battery for long-term use

1.3  Radar probe specification

  • Measuring Method: FMCW
  • Frequency: 24.000 ~ 24.500 GHz
  • Measurement output power: 6dBm
  • Measure range: 0.5 ~ 20m
  • Accuracy: ±0.1m
  • Resolution: 0.01m
  • Horizontal Angel: 78°
  • Vertical Angel: 23°

1.4  Storage Temperature

 -40°C to +85°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  Specification

Common DC Characteristics:

  • Supply Voltage: 2.1v ~ 3.6v
  • Operating Temperature: 0 ~ 70°C

NB-IoT Spec:

  • B1 @H-FDD: 2100MHz
  • B3 @H-FDD: 1800MHz
  • B8 @H-FDD: 900MHz
  • B5 @H-FDD: 850MHz
  • B20 @H-FDD: 800MHz
  • B28 @H-FDD: 700MHz

1.7  Installation

Sensor measure direction and angle is as below. When install the sensor, please make sure the sensor direct to object.



1.8  Pin Definitions and Switch


2.  Use NMDS200 to communicate with IoT Server

2.1  How it works

The NB-IoT network will forward this value to IoT server via the protocol defined by NMDS200.

The diagram below shows the working flow in the default firmware of NMDS200:


2.2 ​ Configure NMDS200

To use NMDS200 in your city, make sure to meet below requirements:

  • Your local operator has already distributed an NB-IoT Network.
  • The local NB-IoT network used the band that NMDS200 supports.
  • Your operator is able to distribute the data received in their NB-IoT network to your IoT server.

Below figure shows our testing structure. Here we have NB-IoT network coverage by China Mobile, the band they use is B8.  The NMDS200 will use CoAP( or raw UDP( or MQTT( or TCP( to send data to the test server.


2.2.1  Insert NB-IoT SIM card

Insert the NB-IoT Card get from your provider.

User needs to take out the NB-IoT module and insert the SIM card like below:

image-20221021110745-6.png ​

2.2.2  Connect USB – TTL to NMDS200 and configure it

User need to configure NMDS200 via serial port to set the Server Address / Uplink Topic to define where and how-to uplink packets. NMDS200 support AT Commands, user can use a USB to TTL adapter to connect to NMDS200 and use AT Commands to configure it, as below.





In the PC, use below serial tool settings:

  • Baud:       9600
  • Data bits: 8
  • Stop bits: 1
  • Parity:      None
  • Flow Control: None

Make sure the switch is in FLASH position, then power on NMDS200 by connecting the Yellow Jumper.


NMDS200 will output system info once powered on as below, we can enter the password: 12345678 to access AT Command input. 

Note: the valid AT Commands can be found at:  https://www.dropbox.com/sh/351dwor6joz8nwh/AADn1BQaAAxLF_QMyU8NkW47a?dl=0

2.2.3  Use CoAP protocol to uplink data

Note: if you don't have a CoAP server, you can refer this link to set up a CoAP server: http://wiki.dragino.com/xwiki/bin/view/Main/Set%20up%20CoAP%20Server/

Use below commands in NMDS200:

  • AT+PRO=1                                                // Set to use CoAP protocol to uplink
  • AT+SERVADDR=,5683       // Set CoAP server address and port
  • AT+URI=0,0,11,2,"mqtt"                        //  Set CoAP resource path

For parameter description, please refer to AT command set


After configuring the server address and reset NMDS200 (via AT+ATZ ), NMDS200 will start to uplink sensor values to the CoAP server. 

1670405841875-916.png ​

2.2.4  Use UDP protocol to uplink data(Default protocol)

AT Commands:

  • AT+PRO=2      //  Set to use UDP protocol to uplink
  • AT+SERVADDR=,5601      //  Set UDP server address and port
  • AT+CFM=1           //  If the server does not respond, this command is unnecessary



2.2.5  Use MQTT protocol to uplink data

AT Commands:

  • AT+PRO=3                                                 //  Set to use MQTT protocol to uplink
  • AT+SERVADDR=,1883         //  Set MQTT server address and port
  • AT+CLIENT=CLIENT                                  //  Set up the CLIENT of MQTT
  • AT+UNAME=UNAME                               //  Set the username of MQTT
  • AT+PWD=PWD                                        //  Set the password of MQTT
  • AT+PUBTOPIC=NSE01_PUB                    //  Set the sending topic of MQTT
  • AT+SUBTOPIC=NSE01_SUB                    //  Set the subscription topic of MQTT



MQTT protocol has a much higher power consumption compare with UDP / CoAP protocol. Please check the power analyze document and adjust the uplink period to a suitable interval.

2.2.6  Use TCP protocol to uplink data

AT Commands:

  • AT+PRO=4                                               //  Set to use TCP protocol to uplink
  • AT+SERVADDR=,5600       //  Set TCP server address and port



2.2.7  Change Update Interval

User can use below command to change the uplink interval.

  • AT+TDC=7200        // Set Update Interval to 7200s (4 hours)


1.  By default, the device will send an uplink message every 4 hour.

2.3  Uplink Payload

The uplink payload includes 23 bytes in total by default.

Each time the device uploads a data package. The user can use the AT+NOUD command to upload the recorded data.Up to 32 sets of recorded data can be uploaded.

ValueDevice IDVerBATSignal StrengthMODExit flag Distance 1  Distance 2

1-32 group

Time stamp Distance 1  Distance  2Time stamp...

If we use the MQTT client to subscribe to this MQTT topic, we can see the following information when the NMDS200 uplink data.


The payload is ASCII string, representative same HEX: 0x f867787050471071  0064  0cc3 09 01 00 00ef 013d 6390453d


  • Device ID: 0x  f867787050471071 =  f867787050471071
  • Version:    0x0064=100=1.0.0
  • BAT :    0x0cc3 = 3267 mV = 3.267V
  • Singal: 0x09 = 9
  • Mod:   0x01 = 1
  • Exit flag: 0x00 =0
  • Distance 1: 0x00ef=239
  • Distance 2: 0x013d =317
  • Timestamp: 0x6390453d =1670399293 (Unix Time)

2.4  Payload Explanation and Sensor Interface

2.4.1  Device ID

By default, the Device ID is equal to the last 15 bits of IMEI.

User can use AT+DEUI to set Device ID



The Device ID is stored in a non-erase area, Upgrade the firmware or run AT+FDR won't erase the Device ID.

2.4.2  Version Info

Specify the software version: 0x64=100, which means firmware version 1.00.

For example 0x00 64 : This device is NMDS200 with firmware version 1.0.0.

2.4.3  Battery Info

Check the battery voltage for NMDS200.

Ex1: 0x0B45 = 2885mV

Ex2: 0x0B49 = 2889mV

2.4.4  Signal Strength

NB-IoT Network signal Strength.

Ex1: 0x1d = 29

0         -113dBm or less

1         -111dBm

2...30  -109dBm... -53dBm

31       -51dBm or greater

99       Not known or not detectable

2.4.5  Distance


Object1 Distance:

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

For example, if the data you get from the register is 0x02 0x05, the distance between the sensor and the measured object is

0205(H) = 517 (D) = 517 cm.

Object2 Distance:

Distance between sensor probe to the second object.  (unit: cm)

2.4.6  Timestamp

Timestamp : 0x6315537b =1662342011

2.5  Downlink Payload

By default, NMDS200 prints the downlink payload to console port.

Downlink Control TypeFPortType CodeDownlink payload size(bytes)
TDC (Transmit Time Interval)Any014


  • Set TDC

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

Payload:    01 00 00 1E    TDC=30S

Payload:    01 00 00 3C    TDC=60S

  • Reset

If payload = 0x04FF, it will reset the NMDS200


Downlink Payload: 06000003, Set AT+INTMOD=3

2.6  ​LED Indicator

The NMDS200 has an internal LED which is to show the status of different states. 

  • When the device starts normally, the LED will light up for 1 second.
  • After NMDS200 join NB-IoT network. The LED will be ON for 3 seconds.
  • For each uplink probe, LED will be on for 500ms.

2.7  Distance alarm function

AT Command: AT+ALARM1=min,max

Example 1:

AT+ ALARM1 =60,200           // Alarm when distance1 lower than 60.

AT+ ALARM2 =min,max

Example 2:

AT+ ALARM2 =200,1500      // Alarm when distance2 lower than 1500.

2.8  Set the number of data to be uploaded and the recording time

AT Command:

AT+TR=900        //  The unit is seconds, and the default is to record data once every 900 seconds. (The minimum can be set to 180 seconds, also the time when the alarm function sends an uplink when it detects an alarm)

AT+NOUD=8      //  The device uploads 0 sets of recorded data by default. Up to 32 sets of record data can be uploaded.

2.9  Read or Clear cached data

AT Command:

AT+CDP         // Read cached data

AT+CDP=0    // Clear cached data ​


2.10  ​Firmware Change Log

Download URL & Firmware Change log: https://www.dropbox.com/sh/8elvp2qi9bcv47a/AAAKp0E2nUffztF0tYhqPoE1a?dl=0

Upgrade Instruction: Upgrade Firmware

2.11  Battery & Power Consumption

NMDS200 uses ER26500 + SPC1520 battery pack. See below link for detail information about the battery info and how to replace.

Battery Info & Power Consumption Analyze .

3. ​ Access NB-IoT Module

Users can directly access the AT command set of the NB-IoT module.

The AT Command set can refer the BC35-G NB-IoT Module AT Command: https://www.dragino.com/downloads/index.php?dir=datasheet/other_vendors/BC35-G/  

image-20221118094449-6.png ​

4.  Using the AT Commands

4.1  Access AT Commands

See this link for detail:  https://www.dropbox.com/sh/351dwor6joz8nwh/AADn1BQaAAxLF_QMyU8NkW47a?dl=0

AT+<CMD>?                    : Help on <CMD>

AT+<CMD>                      : Run <CMD>

AT+<CMD>=<value>      : Set the value

AT+<CMD>=?                  : Get the value

General Commands       

AT                            : Attention        

AT?                           : Short Help      

ATZ                          : MCU Reset     

AT+TDC                   : Application Data Transmission Interval

AT+CFG                   : Print all configurations

AT+CFGMOD           : Working mode selection

AT+INTMOD            : Set the trigger interrupt mode

AT+5VT                    : Set extend the time of 5V power   

AT+PRO                   : Choose agreement

AT+RXDL                  : Extend the sending and receiving time

AT+SERVADDR         : Server Address

AT+TR      :      Get or Set record time

AT+NOUD :    Get or Set the number of data to be uploaded

AT+CDP     :   Read or Clear cached data

AT+DEBUG:   Enable or Disable debug mode

AT+ALARM1:  Get or Set alarm of distance1

AT+ALARM2:  Get or Set alarm of distance2

AT+GETSENSORVALUE :    Returns the current sensor measurement

AT+POWERIC :    Get or set the Power IC flag

COAP Management       

AT+URI :    Resource parameters

UDP Management

AT+CFM :   Upload confirmation mode (only valid for UDP)

MQTT Management

AT+CLIENT  : Get or Set MQTT client

AT+UNAME : Get or Set MQTT Username

AT+PWD  :    Get or Set MQTT password

AT+PUBTOPIC :     Get or Set MQTT publish topic

AT+SUBTOPIC :     Get or Set MQTT subscription topic


AT+FDR :          Factory Data Reset

AT+PWORD :   Serial Access Password

​5.  FAQ

5.1 ​ How to Upgrade Firmware

User can upgrade the firmware for 1) bug fix, 2) new feature release.

Please see this link for how to upgrade:  http://wiki.dragino.com/xwiki/bin/view/Main/Firmware%20Upgrade%20Instruction%20for%20STM32%20base%20products/#H2.HardwareUpgradeMethodSupportList

Notice: NMDS200 and LMDS200 share the same mother board. They use the same connection and method to update.

6.  Trouble Shooting

6.1  ​Connection problem when uploading firmware

Please see: http://wiki.dragino.com/xwiki/bin/view/Main/Firmware%20Upgrade%20Instruction%20for%20STM32%20base%20products/#H3.3Troubleshooting

6.2  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. 

6.3  Not able to connect to NB-IoT network and keep showing "Signal Strength:99".

This means sensor is trying to join the NB-IoT network but fail. Please see this link for trouble shooting for signal strenght:99.

7. ​ Order Info

Part Number: NMDS200

8.  Packing Info

Package Includes:

  • NMDS200 NB-IoT 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 support@dragino.com

Copyright ©2010-2022 Dragino Technology Co., LTD. All rights reserved
Dragino Wiki v2.0