Show control

Show control is the use of

Show control networks have largely supplanted older show control typologies. This is primarily due to the maturation of the larger information technology (IT) computing industry, which, due to its scale and dominance, has produced standards, equipment and software which is less expensive than older show control equipment and methodologies and increasingly more reliable and usable in entertainment applications.^[1]

Modern systems are increasingly based upon Ethernet networking. Most manufacturers of entertainment control equipment now include Ethernet ports on their equipment. Ethernet was originally disqualified from consideration for show control because it was slow, non-deterministic, and lacked sufficient bandwidth to handle certain show control functions. These early objections have been overcome with the use of full-duplex switched Ethernet running at 1000BASE-T speeds on a dedicated local area network (LAN).^[1]

MIDI Show Control

The

USITT DMX512-A is the current de facto standard for lighting control systems. It is an asynchronous serial data transmission standard commonly found as a control scheme between computerized lighting consoles and connected dimmers, moving light fixtures, color changers including LED fixtures, and certain effects (fog, strobes) which are usually operated by the electrical (lighting) department in theatres.

DMX512 was originally launched by USITT in 1986. It was updated in 1990 to USITT DMX512/1990. In 1998, the maintenance of the standard was transferred to the Entertainment Services and Technology Association (ESTA). ESTA revised it, and it was accepted by the American National Standards Institute (ANSI) in November 2004 as "Entertainment Technology—USITT DMX512-A—Asynchronous Serial Digital Data Transmission Standard for Controlling Lighting Equipment and Accessories". In 2011, ESTA merged with the Professional Lighting and Sound Association (PLASA), which now manages the standard.^[6] The standard is now called "E1.11 – 2008, USITT DMX512-A".^[7]

At one time, DMX was put forth as a possible show control standard, mainly by the manufacturers of lighting control consoles, but this idea was never widely adopted, due to the speed and network traffic limitations of DMX for show control applications.

Dante, CobraNet, and others

Audio systems have also benefited from digital networking technology.

CobraNet, although an older proprietary standard dating from 1996, still enjoys a large base of installations.^[9] It is regarded as the first commercially successful implementation of networked digital audio. It utilizes layer 2 packets to distribute uncompressed multi-channel digital audio in professional installations. Its first theme park use was to distribute background music (BGM) in Disney's Animal Kingdom park. It also requires a combination of hardware and software to operate, and has been licensed to multiple manufacturers.

Interest in transferring audio over Ethernet arose about the same time the audio industry was making increasing use of digital signal processing (DSP).^[10] Sound engineers had been altering audio through various analog means for many years, but with the advent of fast, low-latency digital chips, audio signal processing moved rapidly into the digital domain.

Time code

Some types of attractions operated by show control are nearly completely based upon clock-driven timing. These are most commonly found in theme parks in semi-automated attractions which are repetitious and not usually subject to variation. Certain

MIDI time code (MTC) is actually a digital representation of SMPTE time code encapsulated as a series of quarter-frame MIDI messages.^[12] MTC was developed in 1986.

Closures & ladder logic

The beginnings of show control technology can probably be traced to the use of relay logic in other industries, most prominently

The lowest level of subsystem is an embedded system. These are typically found in single-purpose devices, such as a professional fog generator. A small microprocessor might be a part of the equipment and be used to control variables such as volume, temperature and communications with other devices. An example is these specifications for the Antari DMG-200 fog machine.

The programmable logic controller, or its cousin the small logic controller, would be the next increase in scale. These are commonly used to control subsystems which vary from moderately-sized to very large pieces of equipment. The unifying factor is that the equipment fulfills a single purpose, whether it be an animatronic figure or an entire ride system. In the earliest days of show control, PLCs were sometimes used as a show controller for an entire attraction. This is no longer done since there are now simpler and more cost-effective solutions for show control.

Entertainment control systems are the highest level of subsystem, often consisting of sophisticated, expensive controllers which fulfill a single purpose. The modern lighting control console is probably the best example of this type of equipment. Some of the largest concert and hotel-casino installations might use three lighting consoles, each with a distinct purpose.

Systems

Show control systems are very widely used in theme parks as a means of synchronizing ride systems with lighting, audio, show action equipment and special effects. They are also used extensively in live shows in theme parks, such as parades, stunt shows, character shows, and special events, including large fireworks displays. They have found increasing use in live theatre, although due to their cost and the necessity for specialists to design and program them, they are mainly found in large Broadway-type productions^[16] or Las Vegas Hotel-Casino production shows.^[17][18] They are also seen in some of the larger concert tours, especially those featuring moving scenery, flying rigs, and special effects. Shows which are performed once or only a few times are often not considered candidates for show control since considerable preplanning and programming is usually required, but this may change as the technology, ease of operation and programming of show control software and systems matures.

It must be remembered that entertainment control does not constitute show control. A computerized lighting console controlling dimmers and lighting effects is not show control. Only when that lighting console is linked to another system, perhaps a computerized audio playback system, does it become show control.

Generally, there are several kinds of show control systems, as well as hybrid systems which may include multiple system types. In theme parks, the overall show controller is referred to as the RSS (ride/show supervisor). The operator interface in these installations is the OCC (operator control console). In the early years of usage, the RSS was probably a PLC. This began to change as entertainment manufacturers began writing software for personal computers, and/or building small, dedicated computing devices. An example of the former was the Richmond Command Cue system, which used an Amiga computer connected to a proprietary frame containing audio control and matrixing, as well as closure capability. The computer maintained multiple cue lists, and could send MSC messages to other subsystems, such as lighting consoles. An example of the latter might be the Alcorn-McBride V-16, which was programmed with a PC, but did not require one in operation. The V-16 was capable of sending cues as serial messages, contact closures, MSC, and could sync to or generate SMPTE LTC.

The Weigl ProCommander HX is a modern example for a stand-alone show controller, which is also capable of audio distribution over Ethernet by using the AES67 Ravenna protocol. ^[19]

References