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Systems and networking

The problem

You've programmed a show on grandMA2 onPC, and now you want real lights to react. Or you want a second laptop as backup, or to send Art-Net to a cheap node, or to drive more universes than one DMX port allows.

The manual's networking chapter is long and written for large touring systems with consoles, NPUs, backup consoles and MA network switches. Most of it you'll never need. This page explains the few ideas that decide whether a small system works.

The idea: stations, sessions and unlocked parameters

Stations
Consoles and onPC installations. They run the show.
Sessions
The manual calls a session "a chat room for MA devices". As soon as more than one MA device should work together, they join the same session (one of up to 31 per network). Everyone in a session shares the same show file: save on one, it's saved on all.
Master
One station in each session is the master. It transmits network DMX (Art-Net, sACN …), executes commands from sequences, sends MIDI, and uploads the show to devices that join.
Parameters
How many attributes the system may control.

The onPC catch: parameters come from hardware

grandMA2 counts parameters, not DMX channels, and the number you may output is unlocked by MA hardware. Every device in the manual's list has a parameter count. The onPC software itself doesn't appear in it: the onPC-specific devices only unlock parameters "when connected with grandMA2 onPC", for example:

Device Parameters
MA 2Port Node onPC 1K 1,024
MA 2Port Node onPC 2K, 4Port / 8Port Node onPC, onPC command wing, onPC fader wing 2,048
MA NPU 4,096
standard MA nodes (not the onPC versions) no expansion

So:

  • onPC alone is a complete programming environment (and works with MA 3D for visualising), but doesn't control real lights.
  • onPC + an onPC wing or onPC node in a session unlocks parameters. Then the DMX goes out of the hardware's DMX ports, and/or as Art-Net or sACN from the session master to any third-party node.
onPC alone grandMA2 onPC laptop, no MA hardware 0 parameters unlocked: no output programming and MA 3D only Fixtures onPC in a session Session · Network DMX if Alone on grandMA2 onPC session master: sends network DMX onPC node 2K (or onPC wing) unlocks 2,048 parameters optional: second onPC as backup Art-Net / sACN any node third-party Fixtures DMX ports (XLR) on the node Fixtures Nothing comes out? Check: unlock hardware in the session, Network DMX if Alone, protocol or port output switched on.
onPC alone unlocks no parameters. In a session with an onPC node or wing, the onPC master sends Art-Net or sACN, and the node outputs DMX on its own ports.

Standalone vs. session, and "Network DMX if Alone"

A station that isn't in a session is standalone. It can only use its own DMX ports and the parameters it unlocks itself. Network DMX protocols are sent by the session master, so even a single station has to run a session to output Art-Net or sACN, with the Network DMX if Alone option switched on in Setup → Network Protocols.

Interpretation

For a hobby setup this means: create a session even if you're alone, enable Network DMX if Alone, and make sure your MA unlock hardware is in that session. If nothing comes out, check those three things first.

Getting DMX out

There are two routes, and you can combine them:

DMX ports (5-pin XLR on consoles, wings, nodes)
Each port is set to Out (or In, or Off) and a universe in MA Network Configuration. Nodes have a fail mode: hold the last values for a time, or forever, if the session is lost.
Network protocols
Art-Net and sACN (send and receive), plus ETC-Net2, Pathport, Shownet and KiNET (send only). Each line maps a range of your universes (LocalStart, Amount) to protocol universes (ExternStart). The output has to be switched on per protocol.

A 19-inch Art-Net to DMX node lying on a flight case backstage, with DMX cables coiled on top

An Art-Net to DMX node backstage: network in, DMX out on 5-pin XLR to the fixtures. Photo: chcleung, Wikimedia Commons, CC BY-SA 2.0.

What can go wrong with output

The manual lists what stops DMX output: a crash, and a show upload. Leaving the full patch setup re-uploads the show and interrupts DMX for a moment (see Fixtures and patch). What a fixture does when DMX stops depends on the fixture itself (DMX hold), or on the node's fail mode.

Single user, multi user, backup

Several stations in one session can be:

  • One user on several stations ("full tracking backup"): all stations share programmer and views. If one dies, you carry on at the other.
  • Several users (multi user): shared show and executors, but each user has their own programmer, views and possibly a limited world.

Both are about bigger setups. For a hobby show, the useful part is that a second onPC in the session works as a live backup.

When it matters, and when not

  • Programming at home on onPC: none of this. Program, and visualise in MA 3D if you like.
  • Driving real lights from onPC: unlock hardware, a session, Network DMX if Alone, and the protocol or port setup. That's all.
  • Skip at first: several stations and multi user, the MA network switch, NPUs, user rights. They are for bigger systems; the one part a hobby show may want is a second onPC as live backup.

Sources