Centralized control and application of digital lighting
With the rapid development of digital technology in all walks of life, the field of professional stage lighting has gradually crossed into the era of comprehensive digitalization.
At present, the domestic large-scale outdoor performances: such as square party, large and medium-sized individual concerts and indoor large and medium-sized stage plays (including studio) used in professional lighting equipment, such as digital dimmer table, computer light control, digital silicon box, computer effect lights, computer color changing lights, chasing lights computer color changer, laser lights and so on, the vast majority of the majority of the use of digital control. And these devices are connected to each other how to achieve accurate and error-free manipulation, to achieve the overall scheduling of stage lighting, is the majority of lighting control are headaches. Modern stage lighting designers put forward a new management concept for stage lighting - unified management, centralized control. Is the function of the effect of multiple digital lighting equipment connected by a digital dimmer control. For example, we will digital dimmer silicon box, digital color changer, computer effects lights, computer color lights, digital smoke machine, digital bubble machine, etc. are connected to a computer console, controlled by a lighting engineer. Practice has proven to be feasible. This involves the DMX512 signaling system, which is well known in the industry.
DMX is DigitalMultipiex abbreviation. Translated as Digital Multiplexing Protocol, defined by the U.S. Institute of Theatre Technology (USITT), has been recognized and complied with by the world's production stage equipment manufacturers as a widely adopted digital lighting data protocol; that is to say, each controlled unit in this link to meet the requirements of this protocol in order to achieve centralized control.
DMX is based on RS422/RS485 serial transmission, data transmission rate of 250Kbit/s maximum loop control for 512 (of course, there are also 1024 \ 2048 circuit, but that's on the basis of the 512 compounded into). Due to the high DMX signal transmission rate and the special needs of the application environment, DMX signal line, signal to interface and signal transmission between each unit have strict requirements to ensure the accuracy of signal transmission.
DMX allows an effective transmission distance of 250 m. The condition is to use high-quality signal lines, and in the construction to be placed in an independent shielding tank; if the flow of the performance or external interference is serious, to reduce the length of the signal line accordingly to shorten the transmission distance. If the project requires that the transmission distance of the signal line is greater than 250m, it should be installed with a signal amplifier that complies with the 512 protocol. Normally, a DMX512 interface can drive up to 32 digital devices; if all DMX487 integrated blocks are used on the receiving end to receive signals, then a DMX output interface can drive up to 128 digital devices.
If a DMX512 system has more than 32 devices, a signal splitter should be installed, which serves as signal isolation, signal distribution, and signal amplification. A signal splitter has 2~6 output ports (imported 4~8 output ports), a signal input port, a loop interface, it can meet the small and medium-sized stage or studio lighting system signal distribution; if in the larger square (such as stadium), it is necessary to install more than one signal splitter to meet the system needs.
In stage practice, such as this in the multi-unit centralized control of the link installed in line with the DMX512 protocol signal distributor, in addition to the signal amplification, impeachment to extend the role of manipulation in the distance, there is another advantage is: if a lighting equipment failure (such as leakage, short circuit, etc.), the distributor has an optoelectronic isolation device, can effectively protect the link in the light of the equipment. In a multi-device unit of the DMX link, the last lighting equipment signal interface should be installed "terminal plug", as impedance matching, to eliminate signal transmission in the reflection phenomenon, purify the signal component. This is to ensure that the DMX512 system signal transmission is an important part of the normal. "Terminal plug" of the specific connection is as follows: in a five-core XLR plug between the 2 ~ 3 feet welded between a 90 ~ 120Ω 1/4W small metal film resistor, the size of its impedance should be referred to the dimmer Taiwan's operating instructions. When done, plug it into the signal output of the last device can be. There are also some digital lighting equipment itself has a terminal switch, this equipment if placed at the end of the entire link, the switch should be set to allow the position, otherwise it should be moved to an invalid position.DMX protocol requires the use of five-core plug-in in the link. In the construction of only three cores, namely: 1, 2, 3 cores, 4, 5 cores set empty. Most of the imported equipment for the current lighting system is using five-core interface.
In summary, do a good job of centralized control of large-scale lighting systems, the need for construction personnel to clarify the concept of standardized installation in order to ensure reliable operation of the system. Thus ensuring the smooth play of large variety shows, major conferences and other on-site lighting effects.