Bosch BMCT-SLZ: Add Tilt Control Via Zigbee2MQTT

Aug 6, 2025 by Pedro Alvarez 49 views

Feature Request: Add Tilt Functionality to Bosch BMCT-SLZ (Light/Shutter Control II)

Hey everyone! Today, we're diving into a feature request to enhance the functionality of the Bosch BMCT-SLZ (Light/Shutter Control II) within Zigbee2MQTT. This device, a versatile Zigbee shutter/blind controller, currently supports position control, but we're aiming to unlock its full potential by adding tilt control for those sweet lamella adjustments. Let's get into the details!

Is there a problem? The missing Tilt Control

The Bosch BMCT-SLZ, also known as the Bosch Light/Shutter Control II, is a fantastic device for automating your blinds and shutters. You can find all the specs and details on the Zigbee2MQTT device page. This nifty gadget supports both position and tilt control when used with the official Bosch Smart Home Controller. However, here's the catch: tilt control is currently missing in action within Zigbee2MQTT. So, while we can open and close our shutters like pros, adjusting the lamella angle is off the table for now.

During the initial setup in the Bosch app, users get to choose the device type – jalousie (venetian blind), rolladen (roller shutter), or markise (awning). This selection is super important because it dictates the available control features, especially the tilt function for jalousie setups. Think about it – if you've got venetian blinds, you want to be able to fine-tune the angle of those slats for the perfect light and privacy balance. Without tilt control, you're missing out on a key feature of this device.

Proposed Solution: Tilt Control via Zigbee2MQTT

The heart of this feature request is to enable the ability to set and read the tilt angle of the lamellas, giving users full command over their jalousie slats. The device already nails the shutter position (open/close) functionality, but the missing piece is the tilt or tilt_position exposure. We need to bridge this gap to unlock the device's full potential.

Here's the plan of attack:

Expose tilt or tilt_position in MQTT: This is the crucial first step. We need to make the tilt functionality accessible within the MQTT ecosystem, allowing it to be controlled via Zigbee2MQTT.
Allow users to set the tilt percentage: Imagine being able to set the tilt from 0–100% directly from your Home Assistant interface! This level of granular control would be a game-changer.
Report the current tilt state: If the device can report its current tilt state, this would add another layer of precision and feedback, making the user experience even smoother.

By implementing these features, we can transform the Bosch BMCT-SLZ into a truly versatile blind and shutter controller within Zigbee2MQTT.

Alternatives Considered: A Tilt-Control Thought Experiment

We've brainstormed some alternative approaches to achieve tilt control, but none quite hit the mark:

Stop/Pause Commands: One idea was to use stop/pause commands to try and inch the slats into the desired position. Unfortunately, this method falls short in delivering reliable or precise tilt control. It's like trying to paint a masterpiece with a shaky hand – the results are unpredictable.
Bosch’s Original Gateway: Sure, we could stick with the Bosch Smart Home app and its original gateway, where tilt control works flawlessly. But that defeats the purpose of integrating the device into a unified Zigbee2MQTT ecosystem. We want the flexibility and control that Zigbee2MQTT offers, without being tied to a proprietary system.

These alternatives highlight the need for a dedicated and precise tilt control implementation within Zigbee2MQTT.

Context: Tilt is Working, Hardware is Ready!

Here's the good news, guys: Tilt functionality is already working like a charm in the Bosch Smart Home app when using the original gateway. This is a major win because it confirms that the hardware itself is fully capable of tilt control. The Bosch BMCT-SLZ has the potential; we just need to unlock it within Zigbee2MQTT.

This context underscores the feasibility of the feature request. We know the device can do it; we just need to make it happen in our favorite home automation environment.

Additional keywords that related to tilt function

Understanding Tilt Functionality in Smart Home Systems

In the realm of smart home automation, tilt functionality refers to the ability to control the angle of slats in devices like venetian blinds or jalousies. This feature is crucial for fine-tuning the amount of light and privacy in a room. Unlike simple open/close controls, tilt allows for nuanced adjustments, creating a comfortable and energy-efficient living space. When we talk about devices like the Bosch BMCT-SLZ, which is designed as a Zigbee shutter/blind controller, the expectation is that it should support not just basic positional controls but also the sophisticated tilt adjustments that users have come to expect from modern smart blinds. The integration of tilt functionality involves several layers, from the physical mechanics of the device to the software commands that control it. In Zigbee2MQTT, this means ensuring that the device's capabilities are accurately represented and that users have intuitive controls to set the desired tilt angle. This often involves exposing specific MQTT topics that allow users to send commands (e.g., setting a tilt percentage) and receive status updates (e.g., the current tilt angle). The absence of tilt control in a device that is inherently capable of it, like the BMCT-SLZ, represents a significant gap in functionality, hindering the user experience and limiting the device's potential.

Technical Aspects of Implementing Tilt Control in Zigbee2MQTT

Implementing tilt control in Zigbee2MQTT involves a deep dive into the technical specifications of the device and the Zigbee protocol itself. Devices like the Bosch Light/Shutter Control II communicate using specific Zigbee clusters and attributes, which need to be correctly interpreted and translated into MQTT messages. For tilt control, this typically involves identifying the appropriate cluster that governs the angular positioning of the slats. Once the cluster is identified, the next step is to map the device's specific tilt range (e.g., 0-100%) to a corresponding MQTT range. This mapping ensures that users can intuitively control the tilt using familiar percentages or angles. Furthermore, the implementation should account for feedback mechanisms. Ideally, the device should report its current tilt position, allowing the user interface (e.g., Home Assistant) to accurately reflect the state of the blinds. This feedback loop is crucial for creating a seamless and reliable user experience. The Zigbee2MQTT software acts as a bridge, translating MQTT commands into Zigbee commands and vice versa. This requires careful coding and testing to ensure that the tilt control is responsive, accurate, and reliable. In addition to the core functionality, considerations should be given to edge cases, such as handling invalid tilt values or dealing with devices that don't accurately report their position. By addressing these technical aspects, we can unlock the full potential of devices like the BMCT-SLZ and provide users with a truly smart blind control experience.

User Experience and Benefits of Tilt Functionality

The user experience is paramount when it comes to smart home automation, and tilt functionality plays a key role in enhancing this experience for devices like the Bosch BMCT-SLZ. Imagine being able to precisely adjust the angle of your venetian blinds with a simple slider in your Home Assistant interface. This level of control allows you to fine-tune the amount of natural light entering your room, creating the perfect ambiance for any activity. Whether you're working from home, watching a movie, or simply relaxing, tilt control gives you the power to customize your environment to your exact preferences. Beyond aesthetics, tilt functionality also offers practical benefits. By adjusting the slats, you can optimize natural light to reduce the need for artificial lighting, saving energy and lowering your electricity bills. In the summer months, tilting the blinds can help deflect harsh sunlight, keeping your home cooler and reducing the strain on your air conditioning system. In the winter, you can angle the slats to maximize sunlight exposure, warming your home naturally. From a security perspective, tilt control allows you to subtly adjust the view into your home, enhancing privacy without completely blocking out the light. Overall, the user experience of tilt functionality is one of convenience, customization, and control. By adding this feature to devices like the BMCT-SLZ in Zigbee2MQTT, we can empower users to create truly smart and comfortable living spaces.

Let's make this happen, guys! Adding tilt control to the Bosch BMCT-SLZ in Zigbee2MQTT will unlock its full potential and give users the precise control they deserve. Let's discuss and collaborate to bring this feature to life!