3 Control systems
3.1 Components of control systems

A control system consists of the following components:

- Central controller - industrial computer with control program and control ports
- User interface - touch panels, remote controls, button panels, virtual UIs (tablets, smart phones, etc.)
- Communication gateways - modules for technology management (lighting, heating, air conditioning, VZT, etc.)
- Environmental detectors - door switches, access systems, presence sensors
- Software and applications – e.g. remote administration, reservation systems, monitoring, help desk

Current control systems include a wide range of hardware and software. The key features include the user’s interface and the controller. In addition, the control system includes a variety of communication gateways, detectors, software and applications that open other features to the system while opening these functions outward. In practice, it is possible to connect control systems in individual rooms and connect them to remote management or to other technologies in the building, e.g. lighting control, heating, air conditioning, blinds, etc. With the software, the AV/IT administrator manages, monitors and analyzes all available systems throughout the building in one central location.

## Central controller

The central component in the control system is the central controller. It is the “brain” of the entire control system. The controller runs a specific program that receives inputs or control requests from the user and controls individual devices as required by the program. The control system programmer modifies software so that the controller performs the correct functions. It may be required to operate the devices in several rooms across the university campus or even at the other end of the world. There may be a need for multiple linked controllers in this advanced configuration.

A controller and attached devices must be able to communicate to make the required commands. Available types of communication or control signals vary based on the capabilities of the controller and the devices. Communication between devices may be one way or two-way. In a bidirectional communication system, the controller sends instructions to the device (on the Ethernet interface). The device executes the instruction and sends back an acknowledgment (OK response) to the controller. This is called feedback and allows the user to see device status at any time. Communication can also be conducted in just one direction. It is known as one-way communication (relay contacts are one way). Unidirectional (one way) communication is often the only available type of communication between the controller and the device. The command is sent to or from the device and does not follow any confirmation that the command has been executed.

Central controller and its role in AV set

Controllers in a control system may be equipped with various types of peripherals for direct control of components of an AV system. These peripherals are used by the software drivers within the program stored in the controller to invoke certain functions and activities. For example, turning on/off the projector, rolling up or down the screen, turning the light on/off. Control system manufacturers offer many different types of controllers that have different types and numbers of peripherals. The AV system designer chooses the type of controller that meets the requirements of the solution. Some manufacturers offer the option of additional extension of standard peripherals via expansion modules.

Peripherals can process commands unidirectionally (simplex), i.e. either in or out of the device. Some peripherals process the data bidirectionally (duplex) by transmitting commands to the device on the same communication cable, and on the other hand they receive information from the device whether or not the command has been executed. Bidirectional communication can also be used to actively retrieve state information that is stored in the device’s memory, such as information on operating temperature, number of hours in operation, error states, etc.

## User’s Interface

An important, if not the most important, component of the control system is the user’s interface. It is made either in a form of a simple button driver or by a graphical touch environment on the control panel display. User needs determine the right type of user interface. In a small room, a wall-mounted keyboard is usually enough, but a large meeting room cannot do without clear graphical control. To simplify the control, the functions can be put together into preferences or scenarios. It is not necessary, therefore, to have one button for each AV/IT system. In addition to AV/IT, it is possible to integrate lighting control, pulling blind, comfort temperature setting and other technology into the user’s interface.

Peripherals of the user’s interface

The peripherals that are part of the user interface are:

1. Touch panels

- different diagonals from 3.5 - 21"
- wired or wireless
- table or wall

2. Keyboard / Remote Controls

- different sizes and number of buttons
- table or wall

3. Tablets and smartphone

- Connection to a Wi-Fi control system and an application that emulates a virtual touch panel

A specific part of the user’s interface is the GUI (Graphic User Interface).

The graphical concept of the interface is purely on its creator; however, he/she has to respect the relatively strict rules of user ergonomics. In general, users rate the quality of the entire AV/IT system according to the quality of control, especially reliability, simplicity, intuitiveness and clarity. “Less” can be “more” in this respect. The GUI designer has to carefully evaluate user requirements, habits and standards, AV/IT installed techniques, and other aspects. The result has to be a GUI; in which the user can easily find everything you need without a thick instruction manual.

## Communication Gateways

Communication gateways provide the control system with one-way or two-way communication from and to neighboring systems. They can be embedded in large complex technologies, such as lighting control or ventilation systems. On the other hand, gateways can be used to access from the outside for remote management and technical maintenance. Because there are many of different communication platforms available on the market, the AV/IT system designer needs to know the specific requirements and choose the right interface type. At present, Ethernet communication across all standards is enforced, allowing for integration into existing structured cabling and thus better interconnection with existing technologies.

Examples of other communication protocols/interfaces/standards/technologies:

- EIB (European Installation Bus)
- LonWorks protocol
- DALI (Digital Addressable Lighting Interface)
- Modbus protocol
- DMX (Digital MultipleX)
- KNX standard (KoNneX) - EN 50090, ISO / IEC 14543
- EnOcean technology
- Z-Wave protocol

Examples of communication gates

## Environmental detectors

Environmental detectors are the “eyes and ears” of the control system. Through various types of sensors and gauges, the controller receives information about the environment or situation in a room or building. Based on the program, it is then able to respond to the various values, changes, and suggestions that detectors bring.

For example: a room with a movable sliding wall can be used for two small groups or for one large group. For this purpose, it is possible to divide space using a sliding wall. There is a switch reacts to the position of the sliding wall and thus sets appropriate AV/IT to operate either as two separate systems or one large.

Another example is the motion sensor. The sensor may, if the user enters the room, switch on the light or the light panel with information on occupancy (red - busy, green - vacant).

Thanks to IoT (Internet of Things) technologies, today's modern detectors have their own logic and they are smart. They can communicate directly through different networks (LAN (Local Area Network), WAN (Wide Area Network), LTE (Long Term Evolution), proprietary IoT) and transfer data for further processing and analysis. Therefore, the controller of the control system may not have a direct connection with a cable, but it only needs to be connected to the local computer network. The detector can even activate itself, in other words, without the controller's direct command.

Sample detectors

## Software and applications

Software and applications bring users a great added value to the control system and to develop a relationship with customer, for potential for resale. There are either:

- particular applications for a specific area,
- or complex software that combines several areas together.

An interesting area is the use of personal equipment such as tablets and smartphones not only to manipulate with the equipment, but also as a personal assistant for planning work hours and resources (room, catering, technology, object navigation, etc.). A great issue in the corporate environment is remote administration, monitoring and analytics. Software of this kind provides administrators with comprehensive resource information and offers online support for users regardless of the geographical location of the office or branch of the company. Another extensive area is room reservation, building navigation and resource allocation (e.g. catering, AV equipment rental, cleaning services, etc.).

Some manufacturers offer both apps and cloud-based services. The customer can pre-pay the scope of the service according to the individual request regularly in monthly or annual payments. The advantage is that they do not have to purchase expensive infrastructure and servers for running “On Premises”. Because control systems and their components use network communications over local or global networks, there are no limitations. Some components have their own intelligence (IoT) and communicate directly with the cloud service, i.e. without a dedicated controller.