ControlByWeb® industrial controllers are the go-to when systems integrators need a flexible and easy-to-use I/O device. Now they’re getting even better with a firmware update that adds the MQTT protocol! We’ve been working behind the scenes on this feature and are happy to bring MQTT 3.1.1 to our most popular devices. The initial launch includes the controllers listed below.
MQTT stands for Message Queuing Telemetry Transport. It’s a lightweight messaging protocol that serves as an alternative to HTTP. The protocol was designed to use less processing power and send smaller data packets when compared to other communication methods. Because MQTT is so efficient, it’s a great fit with any IoT device. It operates on a publish-subscribe model, where devices can “publish” messages on specific topics while other devices, which are “subscribed” to those topics, can receive the messages. For example, a temperature monitor can publish messages on the topic “temperature degrees,” and a thermostat can subscribe to that topic to adjust temperature settings based on received messages.
MQTT-Compatible Devices
- X-410™
- X-412™
- WebRelay™ and WebRelay-Quad™
- Plus 400 Series devices running firmware v3.0 or greater
Additional Supported Protocols
- SNMP
- API
- JSON
- XML
- Modbus TCP
- HTTPS
- P2P Networking*
*Peer-to-Peer (P2P) networking is possible between two compatible ControlByWeb devices.
Check Your Device Compatibility
MQTT is available on controllers running firmware v3.12 or later. This firmware version is compatible with any existing 400 Series devices that are currently on firmware v3.0 or later. You can verify your firmware version under General Settings > General Information > Firmware Revision. Review the firmware installation support article to learn how to install the latest firmware for your device.
Note that orders placed in the near future may include 400 Series devices running a previous firmware version. Our team can manually update your devices before they ship. Leave an order note or contact us and we’ll ensure your hardware has firmware v3.12 installed.
Benefits of MQTT
There are many reasons that MQTT may be the best fit for a given application. Here are five—plus limitations to keep in mind. (When in doubt, contact us to go over your application.)
Lightweight and efficient. MQTT messages are small—some as small as two bytes—making them easy to transmit over networks with limited bandwidth. This efficiency is crucial for battery-powered devices and physically remote devices reliant on a potentially unstable network. Unlike heavier standards, the MQTT protocol minimizes data overhead, reducing power consumption and network load.
Responsive and asynchronous. MQTT operates asynchronously, allowing devices to publish and subscribe to topics independently. This asynchronous nature enables near real-time message delivery without blocking other tasks. It’s ideal for scenarios where responsiveness matters.
Reliable and resilient. MQTT supports retained messages, where the broker stores the last message on a topic. New subscribers receive this retained message upon subscription, ensuring they get the latest data. It also offers three levels of QoS, or Quality of Service:
- QoS 0 (At Most Once): Fire-and-forget delivery. No acknowledgment or retries.
- QoS 1 (At Least Once): Ensures message delivery at least once. Retransmissions occur until acknowledged.
- QoS 2 (Exactly Once): Guarantees delivery exactly once, even in the face of network disruptions.
Determine the best products for your application with our Sales Engineers.
As you move from QoS 0 to QoS 2, the reliability increases, but so does the communication overhead (more messages exchanged). There’s a whole lot to know about QoS levels—you can take a deeper dive with EMQX R&D engineer Zibo Zhou.
Secure and private. MQTT allows for authentication using usernames and passwords or certificates. It also supports TLS/SSL encryption for data confidentiality. Brokers can also restrict access to specified topics. And, by nature of the lightweight design, packets are more secure compared to complex protocols.
Scalable and flexible. MQTT brokers can handle thousands of clients simultaneously. It can bridge across networks, connecting different brokers or even integrating other protocols.
Challenges and limitations. Of course, there are some challenges to consider as well:
- Limited support for large payloads. MQTT is optimized for small data payloads. Transmitting large files or multimedia content may not be efficient.
- Centralized broker dependency. The central broker is critical; if it fails, communication breaks down.
- Compatibility with RESTful principles. Evaluate whether MQTT aligns with your application’s architectural principles.
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The ControlByWeb® Difference
To learn more about MQTT, you can visit MQTT.org or get in touch with our team. You’re also welcome to schedule a 15-minute demo to get a feel for our devices.