Show Control

The TiMax2 SoundHub offers comprehensive show control via AMX or Crestron programmable logic controller (PLC), or MIDI.

Show control for theme parks and other large-scale facilities where critical closed-loop implementation is specified may be best achieved using a PLC interfaced via the SoundHub's GPIO port. Custom programming, if necessary, is available from the manufacturer, Out Board Electronics.

MIDI show control (MSC), an open-loop system, is sometimes preferred because of its comparatively low complexity—simpler is better—and much lower expense. As show control guru John Huntington explains in Show Networks & Control Systems, "This open-loop approach was chosen for a number of reasons, first and foremost of which was to keep the standard simple to use, easy to implement, and fast—an open-loop approach keeps traffic on a MIDI link to a minimum. In addition, with an open-loop system the failure of any one device in a show network should not affect any other system on the network—even if the system is waiting for a response from a broken lighting controller, there is no reason to prevent a properly functioning sound computer from executing its cue on time." 

Trigger inputs from limit or end-of-travel switches, PIR motion sensors, beam sensors, pressure mats and other sources, are typically input to the SoundHub via an inexpensive multichannel GPI-to-MIDI interface, such as the MIDI Solutions F8.

 

MIDI Solutions F* front panel

MIDI Solutions F8 8-input GPI-to-MIDI interface

 

Programming Tools, a free software utility available from MIDI Solutions, enables the conversion of switch closures to MIDI program change messages and/or note-on messages that can then be selected as cue triggers in the SoundHub. 

 

Programming Tools screen capture

Programming Tools, a free software utility from MIDI Solutions

 

The Programming Tools utility is also used to program relays in the MIDI Solutions R8 MIDI-controlled relay array to open or close in response to MIDI messages placed anywhere within cues in the SoundHub's timeline editor, thus affording control over machinery, such as foggers and other motorized devices, and process control devices such as water fountains. Messages can also be placed within cues to trigger lighting and fogger presents in MIDI-compatible DMX lighting controllers from ETC, Elation, MA Lighting, Strand, Jands, Martin, and others.

A thunder cue can therefore control a flash of lightning. Since it may be desirable to see the lightning before hearing the thunder, the thunder can be programmed in the Timeline editor at an appropriate interval after the MIDI message triggering the lightning flash.

 

MIDI Solutions R8 rear panel

MIDI Solutions R8 8-output MIDI-to-GPI interface, rear panel

 

Designing for Interactivity

Combining input and output interfaces is the key to designing interactive productions. When visitors or performers trigger SoundHub cues that contain MIDI events for actuating lighting presents and relays, a high degree of interactivity can be achieved, with animated elements responding immediately to movements and gestures of visitors or performers. Additional F8 and R8 units can be added to expand the number of trigger inputs and relay outputs in multiples of eight.

The F8 permits incrementing though a series of up to eight MIDI Note On values per input trigger, providing a degree of non-repetitiveness to exhibit programming.

Adding the MIDI Solutions Event Processor or Event Processor Plus provides additional flexibility: these interfaces are capable of processing MIDI events in almost any way imaginable. MIDI events or ranges of MIDI events can be mapped to other MIDI events. MIDI events or ranges of MIDI events can be filtered. They can be used to trigger other MIDI events, toggle between MIDI events, sequence through MIDI events, scale or cross-fade MIDI messages, transpose notes, scale velocities, map to and from System Exclusive, NRPN, Bank Select messages, and store incoming values in variables for later use.

Almost any device capable of sending a simple contact closure can be used as a trigger, including PIR motion sensors, beam sensors, pressure mats, and foot or hand operated switches. Active devices, such as PIR motion sensors and beam sensors that typically run on 12 volts DC power, require a four-wire hookup—two for power and ground, and two for the contact closure.

 

Trigger interface panel

Custom trigger interface panel for four PIR motion sensors, based on off-the-shelf snap-in modular
components, plus a
MIDI input convenience jack for access to hard-to-reach components:
DC power jack, four
RJ-11 jacks, four 1/4-inch jacks, and two blanks

 

Simple four-wire harnesses can be constructed for active sensors from telephone cable and modular RJ-11 (Cat-3) plugs for quick and easy connection to RJ-11 jacks wired to a common power jack and to individual 1/4-inch phone jacks for patching into the MIDI Solutions F8 switch-to-MIDI interface.

 

PIR motion sensor wired to RJ-11 modular plug

PIR motion sensor wired to RJ-11 modular plug

 

Motion sensors require only 20-25mA each, so most off-the-shelf DC supplies can easily power a number of devices. A 12V laptop power supply rated at 1.6A is capable of powering upwards of 60 sensors.

 

Wireless Triggers

Wireless relays controlled by a push-button key fob may be used to trigger cues remotely. Two cues programmed with different MIDI note on values are triggered in this short demo. Control signal flow: Wireless relays → MIDI Solutions F8 → TiMax SoundHub

 

 

Retriggering

To prevent undesired retriggering, use a MIDI Note On trigger with a duration that corresponds to the interval during which retriggering is to be prevented.

The maximum duration of a MIDI Note On is 127 seconds. If this is not long enough, then the trigger contact closure may be wired through a switched 1/4" mono jack so that it is normalled into one of the F8 inputs. Plugging in a patch cord from one of the R8's relay outputs breaks the normal and routes the contact closure through the relay, which can be programmed with a MIDI message in the Soundhub to stay open for as long as necessary, making the cue “unstoppable” for the duration.

To re-enable a trigger, a "Close Relay" MIDI message may be programmed in the Soundhub to restore the normal contact closure path from the sensor to the F8.

 

 

 

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