MIDI Show Control

showstack / protocols / midi-show-control

Also called MSC, MIDI Show Control 1.1.

A universal real-time MIDI system exclusive message set that carries GO, STOP and RESUME together with a cue number, cue list and cue path. It is the oldest reliable way to make one GO button fire lighting, sound and machinery at the same instant.

Show controlOpenThe MIDI AssociationReported

Stewarded by The MIDI Association (MIDI Manufacturers Association).

Control Small, urgent, must arrive

Small messages that either repeat constantly or fire once. Bandwidth is almost never the problem.

What kills it. Latency and loss on the messages that fire once. A repeating level survives a dropped packet; a GO does not.

The four flows, and why the model is worth having →

What goes wrong

The message is F0 7F <device_id> 02 <command_format> <command> <data> F7. Device ID 127 (0x7F) is all-call, so a receiver left at 127 acts on every message on the line including ones meant for another department.

Command format is a category, not an address. 01 is Lighting (General), 02 Moving Lights, and a receiver only acts on the formats it is set to accept. A format mismatch is the most common cause of "MSC is doing nothing".

Cue data is ASCII digits with 0x00 delimiters between cue number, cue list and cue path. Cue 5 and cue 5.0 are different byte strings, so cues can fire on some numbers and be silently ignored on others.

Nothing acknowledges an MSC message. If the receiver was powered down, on a different device ID or on the wrong command format, the sender reports a perfectly successful GO.

A DIN MIDI line runs at 31.25 kbit/s and everything shares it. A continuous MTC quarter-frame stream on the same cable will delay cue messages by a measurable and variable amount.

MSC is one-directional and has no state. A receiver that missed the GO will not catch up, so a device that came back from a reboot mid-act stays where it was until you send it somewhere.

What speaks MIDI Show Control (23)

23 products — 9 hardware, 14 softwareshow all

Product	Direction	Notes
Bome MIDI Translator Pro Bome Software	bidirectional	MSC messages can be constructed and parsed.
ChamSys MagicQ ChamSys	in needs licence	Listed as Show control alongside MIDI notes and CC in the Unlocked-mode feature list.
disguise Designer disguise	bidirectional
dot2 onPC MA Lighting	bidirectional	MSC input to control executors, and MSC output to control other devices.
Eos Electronic Theatre Controls (ETC)	bidirectional	Local MIDI connections on Eos Ti and Gio; Gio @5 and Ion Xe use USB; other consoles need a Net3 Show Control Gateway.
Isadora TroikaTronix (Mark Coniglio)	in	MSC listed on the specifications page; the show-control page describes triggering cues from external software or hardware over MSC.
Medialon Control System Medialon (Barco)	bidirectional	MSC in and out.
MIDI-OX	in	Generic real-time MIDI monitor; will show raw MSC SysEx bytes on the wire but has no dedicated MSC command decoder.
Millumin Anomes (Philippe Chaurand)	in	MSC GO with no Q-number advances to the next column or plays the timeline; GO with a Q-number launches the Nth column; GO with Q-number plus Q-list selects the board; STOP stops or pauses.
ONYX Obsidian Control Systems	in needs licence	MSC format and device ID are set in I/O settings. Gated behind the same tier as MIDI and timecode.
Protokol Hexler	in	Generic MIDI monitor; would display raw MSC SysEx bytes but is not a dedicated MSC decoder.
QLab Figure 53	bidirectional
Show Cue System (SCS) Show Cue Systems	bidirectional	MSC in and out.
WATCHOUT Dataton	in
7thSense Delta Media Server 7thSense	in	MSC for show control integration.
Avolites Diamond 9 Avolites	bidirectional	MSC in and out.
ChamSys MagicQ MQ500M Stadium ChamSys	bidirectional	MSC in and out.
disguise gx 3 disguise	bidirectional
Eos Apex 5 ETC	bidirectional	Available on the console's own MIDI ports or through a Gateway.
ETC Eos Apex 10 ETC	bidirectional	MSC.
ETC Ion Xe 20 ETC	bidirectional	MSC in and out.
Hog 4 High End Systems	bidirectional
Medialon Showmaster Pro Medialon (Barco)	bidirectional	MSC.

Typical use

One GO button on a stage manager's desk firing several departments at once
Lighting console triggering sound and video playback, or being triggered
Theme park and attraction show controllers sequencing effects
Linking a show controller to a console that has no OSC or network control

The words for it

Glossary entries that name MIDI Show Control, with the false friends that catch people out.

Abort中止／ABORTThe instruction to abandon a sequence rather than pause it. Where a hold freezes everything in place, an abor…

Sources

MIDI Show Control — RP-002-014 v1.1.1 specification — The MIDI Association primary
MIDI Show Control — WATCHOUT 7 User's Guide (device IDs, all-call, sysex layout) — Dataton
MIDI Show Control and MIDI note (command formats, commands, cue encoding) — Electronic Theatre Controls
Cognito Console — MIDI Show Control — Pathway Connectivity / City Theatrical
MIDI Show Control — ratification dates — Wikipedia

Understand the mechanism

How software talks to software How it all runs together

Something wrong, or missing?

Known gaps on this entry: default_ports, implementations. If you can source one of them, that is a ten minute pull request.

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