MQTT collector
Basic settings
The collector settings are used to connect to the MQTT broker.
MqttURL
Description: The connection URL for the MQTT broker. Required: yes Example: tcp://localhost:1883
ClientCertificate
Description: Use a client certificate Required: no Default: false Options: false | true
Username
Description: Username Required: no
Password
Description: Password Required: no
Topics
Description: Comma separated list of topics to subscribe to. (Wildcards are allowed) Required: yes
QOS
Description: QOS with which to subscribe. Required: yes Default: 1 Options: 0 | 1 | 2
KeepAliveSecs
Description: The keep alive period in seconds, before which the client sends a ping to the mqtt broker (default is 30 seconds). On no response received, the connection is closed. Required: no Default: 30
PersistentSession
Description: If the session is persistent, the broker will store the session information and deliver messages to the client when it reconnects. So the broker is responsible for caching the messages until the collector is active again Required: no Default: true
Configuration
This guide provides comprehensive instructions for setting up and configuring the MQTT collector for Factry Historian. It includes installation steps, connection setup, and best practices for secure and reliable data transmission.
Collector Installation
To install the MQTT collector, follow the steps outlined in the Collector Installation Guide .
Connecting the MQTT Collector to a Broker
To connect the MQTT collector to your broker, ensure the following configurations are properly set up:
Authentication
- Provide the username and password required for broker authentication.
Secure Communication (TLS)
- Use a CA certificate to validate the broker’s identity.
- For mutual TLS, include the client certificate and private key.
While TLS is optional, it is highly recommended for secure environments to ensure encrypted communication and prevent unauthorized access.
Quality of Service (QoS)
MQTT supports three levels of Quality of Service (QoS), each offering different guarantees for message delivery:
Level | Description | Guarantee | Use Case |
|---|---|---|---|
QoS 0 | At most once | No guarantee of delivery | Non-critical data |
QoS 1 | At least once | Message delivered at least once (may duplicate) | Recommended for most industrial use |
QoS 2 | Exactly once | Message delivered exactly once | Critical data, higher overhead |
Recommendation: Use QoS 1 or QoS 2 to ensure reliable delivery of measurement data.
Topics
MQTT topics are used to route messages. The collector subscribes to specific topics to receive data.
- Topics act as filters — the collector only processes messages from subscribed topics.
- Measurement configurations can only extract data from these subscribed topics.
Wildcards in Topics
MQTT supports wildcards for flexible topic subscriptions:
Single-Level Wildcard: +
Matches exactly one level of a topic.
Example: factory/+/temperature matches:
- factory/machine1/temperature
- factory/machine2/temperature
Multi-Level Wildcard: #
Matches multiple levels (including zero) and must be the last character in the topic.
Example: factory/# matches:
- factory/machine1
- factory/machine1/temperature
- factory/machine2/status/online
For more information and best practices, refer to: MQTT Topics Best Practices – HiveMQ
MQTT messages
There are multiple types of messages that can be processed via MQTT: