Theatre Design & Technology - Summer 1992 - 55

MIDI
Show
Control 1.0
-TheNew
Standard
CHARLIE
RICHMOND

II rypes of rechnical elemenrs in live shows will
soon enjoy rhe universal
ease and power of srandardised conrrol which
MIDI has for years given complex musical insrrumenr serups. MIDI Show Conrrol (MSC) has recenrly become a new
inrernarional srandard rhar promises ro
do jusr rhis. Born of a proposal pur forrh
by Andy Meldrum of VariXLire in early
1989, discussions among key manufacrurers of high rech show equipmenr rook
place rh roughou r 1990 and 1991 via rhe
US ITT Call Board nerwork's MIDI
Forum. The culminarion of rhis work
was a proposal rhar gained rhe approval
of rhe MIDI Manufacrurers Associarion
(MMA) and rhe Japan MIDI Srandards
Commirree (JMSC), becoming MIDI
1.0 Recommended Pracrice RP-002 on
25 July 1991.
MSC is an exrension of rhe basic
MIDI 1.0 specificarion and remains
complerely comparible wirh all pasr and
currenr MIDI equipmenr. MSC follows
rhe rules for srandard Universal Real
Time Sysrem Exclusive (SysEx) messages,
which has been parr of MIDI from rhe
beginning. Porenrially, rhis means rhar a
single MIDI conrrol nerwork can be used
for communicarion berween all MIDI
equipmenr in very large producrions
wirhour confusion or complicarion.
Moreover, subsranrial advanrages will be
realized by allowing all rhis equipmenr ro
inrercommunicare. MSC is an inrerconnecrion srandard for use between inrelligenr "Conrrollers" and similarly inrelligenr "Conrrolled Devices" and is nor
meanr ro provide or replace lower level
communicarion such as DMX512
berween conrrollers and relarively uninrelligenr "slaves."
In a lighring conrrol applicarion, for
example, MSC would be used berween
rhe srage manager's show contI-ol compurer and rhe lighring console or perhaps
between rwo lighring consoles operaring
rogerher (or borh, even using rhe same
MIDI nerwork) bur nor berween rhe
lighring console and rhe dimmers. Typically, rhe person conrrolling a show oper-

ares a show conrrol com purer connecred
via MIDI ro a variery of conrrollers of
various rechnical sysrems including lighring, sound, rigging, mechanics, pyro,
smoke, lasers, mulrimedia equipmenr,
and more. In essence, rhe MIDI nerwork
becomes an elecrronic communicarion
equivalenr of rhe headser sysrem. Sofrware and sysrems implemenring MSC
and specifically for rhis applicarion are
already available and in use.
This arricle describes only rhe basics
of rhe srandard-rhe comple~e MSC 1.0
srandard is publicly available from rhe
MMA and is essenrial for anyone seriously inreresred in MSC implemenrarion. A
good working knowledge of rhe MIDI
1.0 srandard, also sold by rhe MMA, is
addirionally helpful. The self-described
purpose of MSC is "ro allow MIDI sysrems ro communicare wirh and ro conrrol dedicared inrelligenr conrrol equipmenr in rheatrical, live performance,
mulri-media, audio-visual, and similar
environmenrs." For maximum speed,
simpliciry, reliabiliry, and cosr-effeCtiveness, rhis firsr version of MSC runs in an
"open-loop" environmenr, requiring no
response from rhe Conrrolled Device. A
"closed-loop" version of MSC, meering
rhe needs of fail-safe conrrol under rhe
mosr crirical condirions, is currently
under development. Again, from rhe
srandard, "The guiding philosophy
behind live performance conrrol is rhar,
as much as possible, failures of individual
Conrrolled Devices should nor impair
communicarions wirh orher Conrrolled
Devices."
In any case, MSC is nor cerrified as
rhe sole conrrol dererminanr under liferhrearening condirions. In rhese siruarions, rhe mosr rigid safery procedures
and sysrems must always be present. As
rhe srandard clearly srares, "MIDI Show
Conrrol is nor inrended ro rell dangerous
equipmenr when ir is safe ro go; ir is only
inrended ro signal whar is desired if all
condirions are acceprable and ideal for
safe performance. Only properly designed safery sysrems and rrained safery
personnel can esrablish if condirions are
acceprable and ideal ar any rime."
TD&T

1992 SUMMER

53
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