The next generation of building controllers opens up a new intelligent experience

With the continuous advancement of science and technology and people's pursuit of higher quality of life, smart buildings have become an important direction for future architectural development. The emergence of smart buildings is mainly to intelligently control and optimize the building environment. It applies modern sensors, network communications, automatic control, security, audio and video and other advanced technologies to optimize and combine building structures, equipment, services, etc. to form an organic whole and realize Energy-saving, safe, comfortable and sustainable built environment further promotes the construction of smart cities.

At the same time, global challenges such as urbanization and climate change are also accelerating the demand for smart buildings. By using multiple data sources in a secure, scalable, connected system, effective decisions can be executed in real time, resulting in a more energy-efficient and efficient environment. High-precision data enables real-time driving and interaction between buildings and users, creating a safe and efficient space that can be applied to many fields such as commercial, residential and even industrial.

Figure 1: Building control system

Building automation systems can maximize comfort, safety and energy efficiency while supporting scalability. From HVAC to lighting, fully improving performance requires a complex and reliable network that provides accurate data and connections. As building control systems become more localized, platform solutions are emerging that can save time and costs. Their low power consumption and flexibility make buildings easier to reconfigure to meet changing needs.

ADI's building automation system technology can meet the challenges of the proliferation of connected devices and support the realization of smart buildings. These smaller, scalable, low-power solutions enable monitoring, control and reconfiguration at local or higher levels using a building control platform approach, adapting not only to existing building network topologies and standards, but also to new, more advanced technology.

As shown in Figure 2, the building automation system is divided into four layers. The first layer from top to bottom is the Management Layer, where the server equipment and upper-layer management technology are all reflected. This layer can query the current working status of each subsystem through the server on the computer.

The second layer is the network distribution layer/integration layer. This layer will face each control device. The subsystems of the integration layer may manage a small system, such as lighting system, temperature system, heating system, etc. A common system, etc., which not only facilitates classified management, but also allows the development of more complex systems.

Next is the controller layer (Controller Layer). This layer has gone deep into the distributed control mentioned above. The core device of distributed management is here. It can be understood as an on-site brain through which decisions can be made quickly. For example, after it is discovered that the temperature is too high, the built-in PID algorithm is used to drive the fan to work faster to lower the temperature. Therefore, the building controller has a large number of analog sensor I/Os.

The bottom layer is the sensor layer (Field sensor Layer). This layer will be connected to a large number of sensors to sense the status of the site or the entire building. It is the key to obtaining information, so it is very important. In fact, strictly speaking, there is the last equipment layer, which includes compressors and other equipment. This layer is sometimes also connected to the controller layer. In short, it is the on-site equipment.

Figure 2: Building automation system

Modern building automation systems connect elevators, water pumps, fans, air conditioners, HVAC, lighting and other equipment together to achieve online monitoring. By setting corresponding sensors, the travel switch automatically controls parameters such as temperature, humidity, and lighting. As the core equipment of building automation, the building controller (Direct Digital Controller) is responsible for receiving system settings from the host computer, receiving real-time data from on-site sensors, and outputting control actions, thereby realizing a true closed-loop control system.

The building controller is also called a digital controller. Its core task is to sense external analog and digital inputs/outputs, because it has built-in many PID control units required for building automation to control the entire system. ADI has many products in building control systems, which can be roughly divided into several categories such as Software 10, 10Base-T1L, RS-485 and SPoE. The corresponding product introductions are below.

ADI product introduction

Input/output, analog input/output are the key signal input, output and action interfaces of building controller equipment. The traditional control system uses a complex set of channel modules, analog and digital signal converters, and machines and instruments related to the operating surface. Separate wired inputs/outputs to communicate with sensors require costly and labor-intensive manual configuration.

ADI's launch of I/O chips for building control and process automation greatly reduces the difficulty of design. It uses common interfaces to respond to different needs, greatly simplifying the complexity of hardware design. At the same time, it flexibly configures channel functions on-site for manufacturers and industrial operators. Possibility is provided.

Excelpoint, a technology-based authorized agent that has cooperated with ADI for more than 30 years, has created a number of solutions close to customer application needs based on ADI's product and solution portfolio over the years and has gained market recognition. Regarding the two methods of transmitting the link, Shijian recommends the AD74412R/AD74413R based on the current market.

Figure 3: AD74412R/AD74413R block diagram 

Both products feature reconfigurable module channels that enable the design of remotely controllable systems quickly and easily without the need for extensive rewiring. This greatly increases the speed and flexibility of implementation for manufacturers and industrial operators, allowing them to make changes without significant increases in costs and downtime.

The AD74412R and AD74413R are four-channel software-configurable input/output solutions for building and process control applications that include functionality for analog output, analog input, digital input, and resistance temperature detector (RTD) measurements through serial Line Peripheral Interface (SPI) integrated in a single-chip solution. The kit uses a 16-bit Σ-Δ analog-to-digital converter (ADC) and four configurable 13-bit analog-to-analog converters (DAC) to provide four configurable input/output channels and a suite of diagnostics. The AD74412R/AD74413R each contain a high-precision 2.5 V internal voltage reference for driving the DAC and ADC, providing a variety of input/output modes.

ADI innovative connection technology: 10Base-T1L

New buildings are equipped with advanced technologies that can remotely control HVAC systems, detect space occupancy, automatically control lighting and monitor environmental conditions, making these buildings more sustainable while also improving the safety and comfort of building occupants . Advanced measurement, connectivity and processing technology developed by ADI to improve the sustainability and health of new and existing buildings, support building retrofits to reuse twisted pair infrastructure, and connect via 10BASE-T1L Ethernet Modern systems.

The core difference between 10Base-T1L and traditional Ethernet is the two-wire system. Conventional Ethernet is a three-wire system or more. Reducing the number of wires can significantly reduce the entire installation requirements, because traditional Ethernet requires dedicated network cables, while 10Base-T1L only needs ordinary twisted pairs to work, which solves the problem. It eliminates the challenges of on-site layout and installation, and is equivalent to using ordinary two-pin cables to obtain 10 Mbit Ethernet speeds.

Figure 4 is a rough topological structure of the entire communication link process in building automation. The data traffic is getting smaller and smaller from top to bottom, but the content is getting more and more. The top is very concentrated and has a large flow, while the bottom is scattered and has a relatively small flow. The building controller in the middle plays an important role in connecting the top and bottom. It converts the digital signals collected on site into digital signals and finally sends them to the server. There will be a lot of communication needs here.

Figure 4: Simplified diagram of building automation communication link process topology

RS-485 is still a relatively mainstream method in building automation. It has been widely used in almost every field of industry or civil use in the past few decades. Its biggest feature is the two-wire system, which is very convenient to use, and this daisy chain form is very easy to install and configure. The communication speed and distance can reach 38.4kbps and 1.2Km respectively.

Although RS-485 is widely used in building automation, the technology also needs innovation. There have also been some problems in the long-term market application process in the past. For example, the debugging of this architecture is relatively difficult. The failure of a single device node will affect the entire bus. It can only be removed one by one for inspection and then installed. In actual smart buildings, The construction area is very large, whether it is an airport, stadium or commercial building, this means a huge workload.

A typical smart building has controllers and various nodes that make up the building automation system. It is not easy to easily connect to all these devices. Excelpoint recommends ADIN2111 , a classic switch product from Analog Devices that is compatible with IEEE 802.3cg and 10BASE-T1L standards. It can introduce Ethernet to controllers and edge nodes in point-to-point, ring and other line network configurations, reducing the workload of the controller. burden, making upgrading easier.