MQTT Sub Client Documentation

Version: 8.1.0

Retrieved: 2025-10-09 15:16:05

MQTT Client Subscriber

The module is used to subscribe to MQTT messages from an external MQTT broker.

This module is designed to be located at the start of a flow.

Settings

Name Requirements Purpose Default
Topic* Length: 1-256 The topic to subscribe to.  
Target Property Length: 1-64 The property that will contain the result data
Host Length: 1-256 The MQTT broker to use.  
Port 1-99999 The port to use on the broker. 1883
Use TLS (Transport Layer Security)     false
SSL Protocol   The SSL protocol to use. Tls12
Allow Untrusted Certificates   For example when the server has a self-signed certificate. false
ClientId Length: 0-256 If this is empty a random id will be generated and used  
QoS   At most once, At least once, Exactly once At most once
Output Format Raw (no formatting)    
Format from JSON Will convert the data property on the input to an object from the specified format Json  
Use LWT Boolean Check to use last will testament false
LWT Topic Length: 0-256 The last will topic  
LWT Payload Length: 0-2048 The last will payload  
LWT QoS   The last will quality of service At most once
LWT Retain   Check to retain the last will testament false

The Topicsetting accepts MQTT wildcards:

+ is single-level

# is multi-level

Credential

This module contains an option to select credentials to use in the module. All credentials supported by the module are presented in a drop-down.

Input

There is no input for this module

Output

The output is a MQTT message with properties specified below.

Name Requirements Purpose Default
data   The actual MQTT message represented as a byte[]  
topic   The topic for the published message  
retain   Flag for knowing if the message is retained  
qos   The quality of service for the message  
dupFlag   True if the message has been sent before  

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