Inspection method for out of control light
Light control must first check the controller program there is no problem, the address encoding lamp there is no problem, control line connection method is not correct, also need to check the line of control of the shield there was no adverse interference, limiting adjustment lamps are appropriate or not.
Computer lamp bulb damage inspection
The most likely to appear in the sound stage lighting the bulb is easy to bad, so there is a problem, check the installation of lighting not reliable, there is no contaminated dust and moisture, but also to check the light bulb cooling is not in the normal range, it is best to check if the voltage is within the normal range, there is no use the power switch is too frequent.
Method for checking interference noise
Professional audio equipment if there is noise, we must first check whether the light interference, sound and lighting power is disconnected, then check the lighting power supply and control circuit is from the audio signal line too close, there is no silicon box from the audio equipment too near the.
In general the speaker system with noise, is usually caused by signal transmission unreasonable situation, so when the signal line shielding problems, ground or signal is not correct, it is prone to the noise. Andy culture is based on a rigorous and professional attitude, and we will be able to do it as long as you want to
The stage lighting equipment shell has the check sequence of electrification phenomenon
The order of the electrical inspection of the equipment shell is first to check whether the power supply line is damaged or not, followed by the correct phase of the line, but also to understand the equipment grounding and voltage is correct
Stage lighting DMX512 control signal transmission line
Since the stage lighting control into the digital era, the DMX512 protocol has long occupied the dominant position of the stage lighting control protocol, and has become one of the most important technologies for every stage lighting worker. However, in practical applications, the selection and use of DMX512 transmission line is very confusing, and the phenomenon of using the signal transmission line which does not meet the requirements is widespread. Not only in the temporary flow performance, but also in the theater construction. Transmission line is a kind of nervous system in DMX512 control, its quality directly affects the transmission quality of control signal. Poor transmission line will threaten the reliability and stability of lighting control, will bring fatal damage to the performance. For the theater, is "the system wiring infrastructure project", people should pay more attention. In recent years, the country set off the climax of the construction of the theatre, the author participated in the evaluation of many theater lighting design scheme and lighting engineering, equipment, in the review found that this problem has not been given due attention. Even in some national key projects, the problem also exists.
What kind of communication cable should be used in the DMX512 control system to make the system work reliably? Why do I have to use a special cable? Why do you use non-standard transmission lines? To answer these questions, we must first understand the DMX512 protocol. DMX512 is the American Academy of dramatic Technology (USITT) developed specifically for data communication between the lighting console and dimmer protocol standard, and later extended to the field of computer control lamp, color changer and other stage equipment. The main content of DMX512 is to make the stipulation of the data protocol of communication, and the main content of it is directly related to the signal transmission cable:
1 communication interface uses the general EIA-485 standard in computer communication, the electrical characteristics of the EIA-485.
2 DMX512 protocol signal transmission rate of 250kbps.
The following is the reliable transmission of DMX512 signal and the analysis of the wire to be used.
Long line problem
On the basis of the theory of radio, there is a long line theory, the so-called "long line" refers to the length of the transmission line can be compared with the current line along the transmission line. It is generally believed that the length of the transmission line is greater than 1/10 wavelengths (L = L), which can be considered as a long term (some people think l > L is a long term). So the line is not necessarily a long line. The frequency of such as the current ordinary personal computer CPU has reached a gigahertz (G, 109) order of magnitude, the motherboard FSB also reached one or two megabytes, so small in the printed circuit board design should also consider the long-term problem. In the long term, some of the general principles of the circuit is no longer applicable, the need to use a dedicated transmission line theory to analyze.
DMX512 control signal transmission rate of 250kbps, that is, to send 250 thousand binary code per second, in other words is to send a rectangular pulse per second, 250 thousand. According to the spectrum analysis theory, contains a lot of harmonic rectangular pulse, even if only to the fundamental frequency and the lowest L - > L condition to calculate, when the frequency is 250kHz, the wavelength is 1200m, then the transmission line is greater than 120m should be regarded as a long-term. In fact, its harmonics can not be ignored, so that the distance is shorter. Therefore, the transmission of DMX signal must be processed as a long line.
In the general line, the capacitance of the circuit on the capacitor, inductance coil resistance in concentrated, concentrated in the resistor, while the resistance of a wire is the distribution of parameters, but also often regarded as the equivalent of an ordinary resistor, this is the so-called lumped parameter circuit. In a lumped parameter circuit, the voltage and current of each point along the transmission line are the same for each given moment |
