How to create a MQTT Gateway ? – Wattsense Support Portal

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This article explains how to create a MQTT Gateway.

The MQTT gateway enables the acquisition of data directly from a Tower/Bridge into your MQTT broker. Possible MQTT brokers include AWS, Azure, IBM, or a custom one.

MQTT Gateway configuration

REQUIREMENTS TO CONNECT YOUR BOX TO YOUR MQTT BROKER :

You'll need your MQTT broker connection information

Broker Address
MQTT Port (1883,8883,etc..)
Client ID
Authentication information (if required)
Certificate (if required)

These informations should be available in your Broker configuration, if not please contact your Broker provider.

First of all, you'll need to create a new MQTT gateway :

Fill the required fields with your MQTT broker parameters.

AUTHENTICATION :

If your MQTT broker require an authentication with Username and Password click on the Authentication button and fill the fields.

TLS CERTIFICATE :

IMPORTANT INFORMATION ABOUT SECURITY IN MQTT SSL/TLS:

The default port for MQTT TLS connection is : 8883

This implies a connection using certificates. Certificates are security files that allows you to authenticate to your broker. If you are using a TLS secured authentication please be sure that you have loaded your CA certificate.

TIPS

It can happen that your broker is not using custom CA certificate but Public one.

In that case, you will still have to load them in the Box. Because we do not stored them by default.

Knowing that, you can now click on the TLS box if you need to specify any kind of certificates.

ADVANCED TAB :

In this advanced tab, the most important field is the Slug name

A Slug is the field that will be identify a property when you will receive it in your broker.

TOPICS :

Uplink topic and Downlink topic are simple strings conformed to one or more topic levels. For instance, topics are case-sensitive.

Each topic is structured with forward slash as delimiters. The forward slash alone is a valid topic.

The broker uses the topics to filter the messages for each client subscribed to the topic.

UPLINK TOPICS

A new feature (available since firmware APPS 6.1.3) allows customization of the Uplink Topic format (per equipment or per property) in order to publish the data to monitoring / controlling software.
MQTT uplink topics structure can be defined according to your needs, using variables and strings. This structure will generate MQTT topics for each redirected property.

The following variables can be combined in the uplink topic structure :

1. equipment name
2. equipment ID
3. property name
4. property ID
5. gateway ID

This feature has been added in order to avoid using slugs to group data. When you used slugs, you had to have a script in your MQTT broker to parse the message and access the slug, and then aggregate the data.

So, you can build the topic structure at your convenience by mixing simple texts / Equipements ID / Properties ID …

Article.MqttGateWay.UplinkTopicFormat.png

Article.MqttGateWay.ListingTopicContents.png

DOWNLINK TOPICS

Since the APPS 6.1.3 firmware version, you can add a wildcard (#) in the downlink topic settings. This multi-level wildcard (#) covers multiple topic levels and must be placed at the end of the topic format.

When a downlink topic finishes with /#, it receives all messages starting with the text before the wildcard character. If the subject is only "#", the client receives all the messages.

Example : If the downlink topic format is

Room1 / Sensor1 / #

Messages sent to the MQTT broker :

Room1 / Sensor1 / Temperature	OK
Room1 / Sensor1 / Pressure	OK
Room1 / Sensor2 / Temperature	NOK

EXAMPLE

FORMAT

Here is the data format you will received :

Uplink Topic (A) :

Here is the format your broker MQTT will received :

Uplink Topic Format :

[{"propertyId":"Slug Name","timestamp":1608652394220.0,"value":12},{"propertyId":"Slug Name","timestamp":1608652394222.0,"value":123456}]

Downlink Topic (B) :

Here is format that your broker MQTT has to respect to send a command :

Downlink Topic Format :

{"propertyId":"Slug Name","requestType":"write","value":XX}

It will define what will be the value of the PropertyId field of each of your futur gateway properties.

By default it will be Protocol and Property Slug

Example :

If we have a Lorawan sensor with a temperature property, the Slug would be :

"PropertyID" : "Lorawan-MyUniqueSlug1234"

NOTE

Property Slug is the uniqueID of a variable, you'll find it in the property configuration itself

Please note that your modifications will be aplied for ALL properties in the Gateway.

MQTT Gateway property configuration

To add properties to your gateway, select the properties button :

Then add Property:

On the next view you'll have the choice between all the properties available, select the one you want to redirect to your MQTT broker and click on Save

Once the properties select, you'll have that kind of view :

Click on "Save changes" to apply the modifications.

Be sure that the Access Type stay as LOCAL in this configuration.

If you need any additional information, please contact us: here