MIlesight EG71 MQTT Setup

Overview

This guide will walk you through setting up EG71 as an MQTT client allowing you to publish the IO values to a broker and write values to the AO and DO points via a Niagara Station.

This guide uses HiveMQ a public MQTT broker, for demonstration purposes. Public brokers are not secure and should not be used in production environments, as data is unencrypted, accessible to others, and not guaranteed to be reliable.

Note this guide does not cover the following:

-setting up or maintaining of MQTT brokers
-how to install and set up the abstract MQTT driver in Niagara
-how to set up the EG71 onboard IO

Requirements

Milesight EG71 with the onboard IO configured
Details of a MQTT broker that you can connect to
An internet connection if the Broker is not hosted on your local network
A running Niagara station with the MQTT driver and JSON tool kit installed

Set up

Setting up the Data Forwarding

Navigate to: Data Service -> Data Forwarding
Click Add
Select MQTT
Fill out the required properties:
- Name: EG71_MQTT
- Broker Address: broker.hivemq.com
- Broker Port: 1883
- Connection Timeout: 30
- Keep Alive Interval: 60
Click Apply
Click the Add button
Select the IO points to be forwarded
Click Save
Click the Global Object Button
Check the connection status is connected if not press connect

If the information is correct the connection status will show connected.

Setting up the topics for sending data to the broker

The EG71 uses wildcard placeholders to generate topics:

"$gatewaySN", "$deviceName", "$devEUI", "$deveui", "objectID", "objectName"

By default the uplink topic for any given IO point will be:

EG71/$gatewaySN/$deviceName/uplink

So for example:

If i want to read the AO-2 on the device with a serial number of 6438F44338050005

I would use topic:

EG71/6438F44338050005/AO-2/uplink

To edit the wildcard place holders navigate to:

Data Service -> Data Forwarding -> Press the icon on the MQTT service

scroll to the bottom of the page

Note the serial number can be found in the top right of the screen

Setting up the payloads

This section explains how to structure the JSON payloads sent to the broker and read by Niagara.

By default the payload will contain all of the meta data

An example of the default payload:

{

  "Present Value": 1.1,

  "applicationID": 4,

  "applicationName": "EG71_MQTT",

  "deviceID": 1,

  "deviceName": "AO-1",

  "gatewaySN": "6438F44338050005",

  "gatewayTime": "2026-04-24T10:22:49+01:00",

  "object": [

    {

      "objectID": 1,

      "objectName": "Present Value"

    }

  ]

}

Meta data can be selected from the Edit MQTT menu

For example we can select just the deviceName, objectID & gateway time selected and the reduced payload would look like this.

{

  "Present Value": 1.1,

  "deviceName": "AO-1",

  "gatewayTime": "2026-04-24T10:34:08+01:00",

  "object": [

    {

      "objectID": 2,

      "objectName": "Present Value"

    }

  ]

}

Reading the Data from the Broker in Niagara

In this section we will configure a new MQTT device on the Niagara station and set up a point to read the current value of an analogue output on the EG71.

Add a AbstractMqttDevice to the AbstractMqttDriverNetwork
Add a defaultAuthenticator to the AbstractMqttDevice
Configure the device to connect to the same Broker as the EG71, for this guide please see details below:
Enter the following under DefaultAuthinticator:
1. Broker Endpoint: broker.hivemq.com
2. Broker Port: 1883
3. Client ID: This can be anything you like
4. Connection type: Select Anonymous
5. Username and password: These can be left blank
Right Click the AbstractMqttDevice
Select Action -> Connect

If the properties have been filled out correctly the status of the driver will change to {ok} and the Status message will show “Connected”.

With the driver setup and connected we can begin pulling in data from the broker.

Navigate to AbstractMqttDevice points folder Mqtt Client Driver Points Manager View
Click new
Add a MqttStringSubscribePoint
Fill out the properties
- Name: AO-2
- Topic: EG71/6438F44338050005/AO-2/uplink
Right Click the AbstractMqttDevice select Actions -> Subscribe All

Note when first adding a point it will show as stale until the topic is written to by the client. We can force it by adjusting the value of the AO-2 in the EG71.

Navigate to: Data Service -> Data Acquisition -> IO Device (tab)
Select the 3 dots for AO-2 on the right hand side of the table.
Click force value
Enter a new value
Check in the Niagara station that the point has been updated with the JSON payload.

Parsing the JSON payload

As the data has come through as a JSON payload now we need to parse out the information we need.

Open the JSON tool kit palette
From the Queues Folder drop an EngineCycleMessageQueue onto the wire sheet
Link mark the ‘out’ of the MqttStringSubscribePoint to the ‘Enqueue’ of the EngineCycleMessageQueue (note it will only update when there is a change in value)
From the Inbound -> Routers folder drop a JsonDemuxRouter onto the wire sheet
In the JsonDemuxRouter properties set the Learn Mode to true
Link the ‘Out’ of the EngineCycleMessageQueue to ‘Route’ on the JsonDemuxRouter

Once the value is updated and a new JSON payload is delivered the point will populate the slots with the JSON field, from here we can link the values we want to other parts of strategy.

Publishing a point from the Niagara station to change a value on the EG71

In this section we will set up a publish point in the MQTT driver on the Niagara station to change the value of the AO-2 point on the EG71.

Understanding what topics to publish to:

The EG71 uses wildcard placeholders to generate topics for you to publish to in order to adjust values.

"$gatewaySN", "$deviceName", "$devEUI", "$deveui", "objectID", "objectName"

By default it is set to:

EG71/$gatewaySN/$deviceID/downlink

The deviceID is the same as the objectID found in the Data Service -> Data Forwarding -> MQTT setup.

For example

If we want to write a value to the AO-2 where its object ID is 2 and is on the device with a serial number of 6438F44338050005

I would use topic:

EG71/6438F44338050005/2/downlink

Constructing the JSON Schema in Niagara

In order to write a new value to the AO-2 we need to construct a JSON payload in the Niagara station to be sent to the broker.

{

 "objectInfo": [

   {

     "objectID": 2, //This is the device ID from the Data Forwarding Page

     "objectValue": "5.6" //This is the value we want the AO-2 to be

   }

 ]

}

Above is how we need the JSON payload to look.

Open the JSON tool kit palette
Drop a Json Schema on to the wire sheet
Open the Properties sheet
Add a Json Schema Object -> Rename to “root”
Add a Json Schema Array to “root” -> rename to “objectInfo”
Add a Json Schema Object to “objectInfo”
Add Json Schema Numeric Property to “Object” -> Rename to “objectID”
Add Json Schema Bound Property to “Object” -> Rename to “objectValue”
Expand the “objectValue”
For the Binding field point it at the numeric writable you want to control the value of the AO-2

When finished it should look like this

When you press generate it should have the same formatting as the example above.

Now when the NumericWritable value is changed the JSON payload will be updated and then sent onto the broker where the UG71 will automatically be subscribing to that topic and update the value of the analogue output.

Troubleshooting

Issue	Possible Cause/ Fixes
The EG71 cannot connect to the broker	Check the EG71 has a connection to the internet. Check the default gateway details. Ensure the Mobile network is set up correctly. Check the signal strength, data allowance.
The AbstractMqttDevice cannot connect to the broker	Check the station has a connection to the internet. Check the default gateway details. Check the firewall is not blocking the port (1883)
The MqttStringSubscribePoint is not showing any value	If the point has just been added as a new point right click the device and click actions -> Subscribe All If the point has just been added an a new point then the value will need to be updated on the field device before registering a value Check the topic has been entered correctly. The topic is case sensitive Check the EG71 wildcard placeholders. Check the spelling, check you are constructing the topic correctly
When publishing a point there is no change to the IO point	Check the JSON payload is formatted correctly Check the topic has been entered correctly. The topic is case sensitive Ensure the deviceID is correct in the JSON payload and in the topic to be published to Check the EG71 wildcard placeholders. Check the spelling, check you are constructing the topic correctly