66 Part 2 · Entertainment Discipline Overview L IGHTING C ONTROL A PPROACHES Now that we've covered various types of lighting devices that might be found in a lighting control system, we can move on to the heart of the control system itself. Analog (0­10V) Control Along with the advent of easily remote-controllable dimmers came the first de facto dimmer control "standard": analog direct current (DC) voltage control. The concept is quite simple: One wire is run from the console to each controlled dimmer and a DC voltage corresponding to the level of the dimmer is sent down the wire. Zero volts represents an off condition; 10 volts (generally) represents a dimmer output of 100% or "full on." In analog-controlled dim- mers, this control voltage is received by trigger circuitry, which generates SCR firing pulses at the proper times to achieve the desired light output. While digital control using DMX (dis- cussed below) is used in the vast majority of modern installations, analog control can still be found in small systems in some low-budget venues, such as clubs, discos, and small theatres. If you're interested in using this low-tech, simple system, please consult the ESTA Standard ANSI E1.3 ­ 2001, 0 to 10V Analog Control Specification. DMX512-A The "ANSI E1.11-2004 Entertainment Technology USITT DMX512-A, Asynchronous Serial Digital Data Transmission Standard for Controlling Lighting Equipment and Accessories" started humbly, but is now the most successful and widely-used entertainment lighting control standard in the world. 2 It has become so successful, in fact, that it is now used outside the lighting world as well--it is covered in depth in Chapter 22, on page 217. Proprietary Ethernet Control Solutions A typical production "tech table" may have several console monitors for the lighting designer, and a remote console data entry unit. Backstage, we may want a few DMX outputs on one side of the stage for some dimmer racks, a few more DMX outputs over the stage for some moving lights, and a remote monitor for the stage manager. In the catwalks, we may want a few DMX outputs and a connection for a remote focus unit. Each of these devices would typically need a different type of cable run separately to or from the main lighting controller and some sort of patching and distribution in the control room. With an Ethernet-based system, a single Ether- net network can be run throughout the performance facility, and the appropriate lighting "node" is simply connected wherever you need data, a monitor, or a remote entry or focus sta- 2. If you encounter obsolete standards, such as USITT AMX192 or Kleigl K-96 on an old dimmer rack, DMX con- verters are available.