MQTT - v5 Generic

6 min

Overview

The MQTT - v5 Generic integration enables Belden Horizon Data Operations to connect to an MQTT v5 broker via TCP or SSL.

Supported versions

Compatible with MQTT Protocol version 3.1.0, 3.1.1, 5.0.0

Supported communication

Outbound (Publish data from Edge to MQTT Broker) - Yes

Inbound (Subscribe data from MQTT Broker to Edge) - Yes

Configurations

Field	Details	Required
Name	Name of the connector instance.	Yes
Connection Type	Choose tcp for an unencrypted connection or ssl for a TLS-encrypted connection to the MQTT broker.	Yes
Hostname	DNS name of MQTT host.	Yes
Port	Port of MQTT host.	Yes
CA Certificate	CA certificate used to verify the server, in PEM format. Can also be installed in the system-wide certificate store.	No
Certificate	Client certificate for mutual TLS authentication with the MQTT broker. Paste the PEM-encoded certificate here.	No
Private key	Private key corresponding to the client certificate. Must match the Certificate field above.	No
Insecure Skip Verify	InsecureSkipVerify controls whether a client verifies the server's certificate chain and host name.	No
Client ID	Client ID is required by MQTT server. If left empty, the system uses InstanceUUID.	No
Username	Username for authenticating with the MQTT broker.	No
Password	Password for authenticating with the MQTT broker.	No
QoS	Quality of Service delivery guarantee: 0 = at most once, 1 = at least once, 2 = exactly once.	No
Integration Topic	MQTT topic path where data is published.	Yes
User Properties	Custom key-value metadata attached to outgoing MQTT v5 packets. Passed through to the broker and available to subscribers.	No
Throttling limit	Set a limit on the number of outbound messages per second. If sending data to a server that has restrictions on the rate of incoming messages, this ensures that no messages are lost.	No

Advanced configurations

Field	Details	Required
Parallel Publish Count	Number of messages published in parallel. Higher values increase throughput and resource usage.	No
Response Topic	MQTT v5 topic the receiver should publish its response to. Used in request-response messaging patterns.	No
Payload Format Indicator	Allowing the server to understand packet without having to operate on the actual data.	No
Content type	MIME type describing the format of the message payload. Informational - passed to subscribers.	No
Topic Alias Maximum	Decrease the size of the MQTT packet overhead by allowing the topic name to be abbreviated to a small integer.	No
LWT topic	MQTT topic the broker publishes the Last Will message to if this client disconnects unexpectedly.	No
LWT payload	Message content published to the LWT topic on unexpected disconnection. Typically a status or alert string.	No
LWT payload type	Encoding of the LWT payload: string for plain text, base64 for binary data.	No
LWT QoS	QoS level for the Last Will message: 0 = at most once, 1 = at least once, 2 = exactly once.	No
LWT retained	When enabled, the broker retains the Last Will message and immediately delivers it to any new subscriber on that topic.	No
Will Delay Interval	Add the ability to specify a delay between the end of the connection and sending the will message.	No
Session Expiry Interval (seconds)	The number that specifies how long a broker keeps a client's session information.	No
Message Expiry Interval	Allow an expiry interval to be set when a message is published.	No
Request Response Info	Request the broker to return response information in the CONNACK packet.	No
Request Problem Info	Request the broker to include human-readable reason strings and user properties in error packets.	No
Keep Alive	Ensure that client remains connected to the broker and maintains an active session.	No
Connection Timeout	How long to wait for the connection process to complete in seconds.	No

Persistent storage configurations

Field	Details	Required
Persistent storage	If enabled, messages in the outbound queue are stored on disk. If there are interruptions in connection or power loss, messages are retained and eventually sent when the connection is restored.	No
Persistent storage size limit	Set the size limit for storing persisted data in GB.	No
Queue mode	Select the sequence of data transfer: FIFO or LIFO. Selecting FIFO (First In First Out) sends the earliest message first. Selecting LIFO (Last In First Out) sends the latest message first.	No

Format directives

Symbol	Definition	Context
$	Special character indicates a variable character follows. A variable represents some dynamic string value. Supported variables defined as follows:	-
$S	Additional Alias definition	from Connector Settings
$D	Device Name	from DeviceHub Tag
$N	Tag Name	from DeviceHub Tag
$R	Raw Tag Type	from DeviceHub Tag
$P	Tag Description	from DeviceHub Tag
$H	Hostname	from OS
%	Special character indicating a function character follows. A function represents some action to be taken on the next variable. Supported functions defined as follows:	-
%L	Lowercase()	apply to next variable
%U	Uppercase()	apply to next variable

Format directives notes

To use a special character in its literal form, enter symbol twice ($$ -> $, %% -> %) Example "$$$D.%%$N" -> "$deviceABC.%tagXYZ"