With the advancement of civilization and the development of science and technology, large-screen display devices have been applied in more and more industry sectors with their excellent performance and outstanding display effects. A set of display systems can operate normally without the support of the control system. This paper mainly introduces a distributed graphic control system based on network digital transmission (referred to as DVCS control system) in the context of traffic industry.
Introduction : The rail transit industry involves railways, subways, light rails, electrified railways, and high-speed magnetic levitation railways. In these areas, there is one thing in common, that is, the requirements of scheduling and information display are involved. As the department of rail transit operation management and maintenance, the control center needs to monitor the operation status of the entire line at all times. In order to ensure the continuous and efficient operation of the rail transit line, and to meet the needs of timely handling of various emergencies, and to quickly make decisions based on relevant information, the large-screen display system has become a good information display platform. It can better help relevant departments to dispatch, maintain, manage, and emergency command, greatly improve the level of transportation management, and build a platform for digital road network automatic control system, which can better meet the development needs of metropolitan rail transit.
Faced with a variety of complex signals and changing application requirements, it is important to choose a suitable control system. This paper will introduce the technical implementation, principle and application advantages of DVCS control system in a comparative way.
First, the traditional control system
1. Built-in screen splicing system
Whether it is a DLP device or a new generation of LCD devices, they all have built-in graphics stitching. Let's take the DLP unit as an example. In the early days, the cost of the graphics control system was high and the equipment was expensive. We use more than one-to-many signal output function of the matrix to provide signals, and then use the built-in image processing function of the optical machine to realize full-screen display and superimposed display of the screen. However, the number of input interfaces of the optical machine is limited and cannot be increased, and only 2-3 signals can be displayed on the screen at the same time. This is not enough for the public security transportation industry, which is mainly based on video surveillance.
2. Centralized control system
With the development of manufacturing industry, the advancement of technology and the decline of cost, multi-screen graphics cards have entered the market and gradually become the main accessories of large-screen control systems. With the board-type structure of the input-output card, we can display many signals to the mosaic wall in a more flexible way. At present, we have adopted such control methods in many public security transportation industries.
3. Embedded control system
While centralized control systems are prevalent in the large-screen splicing industry, many manufacturers have begun to develop hardware-based controllers. The advantages of this type of application are: no operating system; hardware-based interface; convenient extension; low cost. Soon, more and more projects began to introduce this control method, of course, in the absence of very complex applications, this system is still very popular with manufacturers and users.
Second, where is the advantage of DVCS?
1. The background generated by the distributed control system
Distributed systems benefit from three technical factors: network codec technology is becoming more mature, bandwidth of switches is gradually increasing, and video processing technology is getting higher and higher.
It is not difficult to understand that because it is a network-based control system, distributed network bandwidth requirements are more important. We now have industrial-grade switches with bandwidths up to 1000M/port, and we have rack-mounted switches with higher bandwidth. Take the public security traffic industry as an example, this will ensure that a large number of camera signals are connected to the monitoring system through the network. At the same time, its transmission medium is the network cable, the transmission distance is increased, the anti-interference ability is increased, and the construction wiring is more convenient. These are the traditional control systems. Distributed has become the object of many companies, and has become the new darling of the splicing control industry!
2. Structure of distributed control system
Structure of distributed control system
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