Professional stage lighting of digital technology becomes more widespread, more and more professional understanding of the support, and gradually move toward digital manipulation and operation. With digital technology in the rapid development of industries, professional stage lighting gradually stepped into the field of comprehensive digital era. At present, large-scale outdoor performances: such as Square party, concert and medium-sized and medium-sized theater room (including studio) used by professional lighting equipment, such as digital dimming computer lighting control, digital dimmer pack, effect lights computer, the computer for color lights, track lights computer for color, laser lights , the vast majority have adopted digital control. The connection between these devices on how to achieve accurate control, to achieve the overall scheduling stage lighting, lighting controls to make the majority of all headaches.
Unified management, centralized control" the professional stage lighting management concepts into the modern stage lighting designer for stage lighting control and management of the pursuit. More than one function is to effect the number of different lighting devices to connect from one digital dimming control. For example, we have digital dimmer, digital color changers, effects of computer lights, computer lights change color, digital smoke, bubble machines and other digital all connected to a computer console, controlled by a lighting division. Proven to be feasible. Here relates to the industry are known DMX 512 signal transmission system.
DMX is short for Digital Multiplex. Translation of digital multiplexing protocol, by the American Institute of Theater Technology (USITT) definition has been producing the world stage equipment manufacturer recognition and observance, as widely used digital lighting data protocol; that link in this each controlled unit must comply with the requirements of this agreement, in order to achieve centralized control.
DMX is a RS422/RS485 serial transmission-based, data transfer rate of 250Kbit/s for the 512 largest loop control (of course, there are 1024 \ \ 2048 loop, but that is based on the 512 be added together). As the DMX signal transmission rate and the special needs of the application environment, DMX signal cable, signal interface and signal transmission between the various units, there are stringent requirements to ensure the accuracy of signal transmission.
DMX allows the effective transmission distance of 250m. Conditions is the use of high-quality signal lines, and to put it in the construction of a separate shield tank; if serious touring or where external interference, reduced to the corresponding signal line to shorten the length of the transmission distance. If the project requires the transmission distance is greater than the signal line 250m, should install a signal amplifier line 512 agreement. Usually a DMX512 interface can drive up to 32 digital devices; if the receiving end to receive all the manifold uses DMX487 signal, then a DMX output interface 128 is able to drive digital devices.
If a DMX512 system equipment more than 32 units, it is necessary to install the signal distributor, its role is to signal isolation, signal distribution, signal amplification. A signal splitter 2 to 6 outputs (imports are between 4 and 8 outputs), a signal input port, a loopback interface, it can meet the small stage or studio lighting system signal distribution; If the larger square (as sports), it is necessary to install more than one signal splitter to meet system needs.
Practice in professional stage lighting, such as centralized control unit in a multi-link in the installation of a signal splitter in line with the DMX512 protocol, except for the signal amplification, to extend the distance function in the manipulation of impeach, there is a benefit that : If a lighting equipment failure (such as leakage, short circuit, etc.), distributors have optical isolation device, which can effectively protect the link in the lighting equipment.
In a multi device unit in the DMX chain, and finally a light signal interface equipment should be installed "end plug", as the impedance matching in order to eliminate the clutter signal transmission in the phenomenon of reflection, purification of signal components. Then ensure the DMX512 signal transmission system is an important part of the normal. "End plug" of the specific connection as follows: In a fivepin XLR plug weld between 2 to 3 feet a 90 ~ 120Ω 1 / 4 W metal film resistors small, its impedance should refer to the size of the use of dimming instructions. Well, put it into the last device in the signal output can be. There are other digital lighting switch terminal itself, if such equipment placed at the end of the link should be set to allow the position switch, or should be moved to an invalid location. Use the link in the DMX protocol requires five core plug. Only in the construction of three-core, namely: 1, 2 core, 4,5 core empty. Most of the current lighting system using imported equipment are five core interface.
In summary, good stage lighting equipment, large-scale centralized control systems, construction workers need a clear concept, standardized installation to ensure reliable operation. In order to ensure large-scale variety show, the scene of major meetings and other lighting effects play smoothly.
