SLX StagePilot: DMX software and 3D simulation for live shows

Software for live shows

Before connecting a complete rig, it helps to see what happens between a command and its result: which channels change, which personality interprets them, and how a value becomes intensity, colour or movement. Dedicated software makes those steps visible and repeatable.

SLX StagePilot is a Windows application developed by Silicon LogiX to receive DMX data over Ethernet and apply it to a virtual 3D stage. Scene programming, visualisation and stream diagnostics let the operator follow the path from channel values to fixture behaviour.

Its counterpart is an embedded Linux console with a touch interface. Connecting the two applications makes it possible to verify a system with separate responsibilities and a shared protocol.

From fixture to 3D stage

The stage contains 44 virtual devices across 15 types, including Spot, Wash, PAR, LED bars, strobes, blinders, house lights, followspots and lasers. Their profiles occupy 500 of the 512 channels in universe U1.

Selecting a fixture in the list highlights it in the 3D view, even at zero intensity. Ctrl builds a multiple selection; framing brings the selected detail into view. Clicking empty space clears the selection. The stage, truss, instruments and seating remain scenery, providing spatial context and occluding clicks where appropriate.

The simulator displays levels and selection in the same scene. Selecting a fixture does not change its DMX values. Capture of the original application interface.

Movement, emissive materials, beams and procedural effects represent the received parameters. The DMX coverage view distinguishes visual responses from values retained as data only. The Spot optical inspection, for example, exposes gobo and prism mechanisms, while the rendering remains simplified. The application supports integration work and does not replace calibrated photometric calculations.

Receiver, model and renderer

The pipeline separates network reception, application state and rendering. A datagram is validated, matched to the selected universe and converted into levels that the model interprets through the patch. The interface presents the resulting attributes; the renderer updates the affected transforms, colours and geometry.

The same stream can feed a 512-channel monitor and a 3D view. The patch connects bytes to fixture parameters.

This separation lets an observed stage behaviour be compared with the received value and its interpretation. A channel can be correct while the assigned personality is wrong; a fixture can receive valid levels with its shutter closed. Viewing the stage and inspecting the data answer different parts of the same question.

The simulator runs independently and receives Art-Net and sACN. Physical output belongs to the controller or gateway specified for the installation. An API separate from the renderer defines the data contract, allowing different interfaces and tools to use the same fixture model.

Inside an Art-Net packet

Art-Net carries control data over UDP. An ArtDmx packet identifies the protocol, message type, sequence, Port-Address and data length, followed by the levels. It uses UDP port 6454; in StagePilot, U1 maps to Port-Address 0.

This example shows an ArtDmx header for 512 levels, following the format used to verify the project’s receiver:

41 72 74 2D 4E 65 74 00 00 50 | ArtDmx 00 0E | Version 01 00 | Seq. / Physical 00 00 | Port-Address 02 00 | 512 data bytes

The first eight bytes contain the Art-Net identifier terminated by a null byte. The ArtDmx OpCode, 0x5000, is little-endian; the protocol version and data length are big-endian. This example uses sequence 1, Physical 0 and Port-Address 0. Byte order therefore has to be read field by field.

For a 16-bit level, coarse and fine depend on the fixture profile: bytes 128 and 0 represent 32768 out of 65535, which is then mapped to the parameter’s range.

With an 18-byte header and 512 data bytes, a full ArtDmx packet contains 530 bytes of UDP payload. At 40 updates per second, this is 21,200 bytes per second per universe, before network headers. Bandwidth is modest; continuity, routing and the response to packet loss remain central design concerns.

ArtPoll discovers nodes. ArtDmx carries levels. Finding a gateway does not automatically assign addresses and personalities to the fixtures connected to it; patching remains a separate operation.

How sACN works

sACN, ANSI E1.31, encapsulates DMX levels in structures identifying the source component, universe, priority and sequence. The CID identifies the source; a readable source name helps the operator, while the identifier lets the receiver distinguish streams.

The transport uses UDP port 5568 and supports unicast and multicast. With multicast, the receiver joins the group for the required universe; U1 uses IPv4 group 239.255.0.1. Interface selection matters: the group must be joined on the network adapter connected to the lighting network.

Universe priority ranges from 0 to 200, with 100 as the usual default. The receiver must define how multiple sources and source loss are handled. StagePilot exposes the active source and applies an explicit ownership policy. Multi-source merging, per-address priority and synchronisation are additional integration features when required by the installation.

Art-Net and sACN carry control parameters. Video playback, audio tracks and media-server content require their respective playback engines. A DMX channel can select a function or set an intensity without carrying the media file itself.

Sources, sequences and signal loss

UDP does not acknowledge every applied packet to the sender. The receiver needs to check format, length, universe and sequences, and distinguish a recent signal from a value still held in memory. A growing packet counter and the age of the latest frame provide different operational information.

The Ethernet page exposes reception state and the policies applied when the source is no longer available. Capture of the original interface.

StagePilot provides Hold, Fade and Blackout with their timing settings. Hold retains the last state; Fade and Blackout apply the selected policy to intensities. The choice depends on the installation and the responsibilities assigned to the control system.

Continuity also depends on process lifecycle management. The receiver can be opened, closed and reopened while data is arriving. Callback object lifetimes, worker shutdown and the separation of reception from drawing all contribute to desktop application reliability.

Programming and capture

The Programmer prepares local attributes. Scenes, cues and chasers organise looks and sequences, while palettes and effects speed up repeated operations. A show file stores the patch and libraries; a capture records the stream of levels over time.

These support two workflows: editing a show project and replaying a recording to compare behaviour. A capture can reproduce a transition, check a source change or help investigate how channel values were interpreted.

Capture supports up to 32 seconds at 40 Hz, and the application includes a sample show with a soundtrack. The fixture personalities are SLX virtual profiles. Integrating a real fixture starts with its channel map, parameter ranges and selectable device modes.

Verifying the complete system

Verification compares data as well as its representation. An independent generator sends ArtDmx frames with known levels. The 512 received slots are compared with the expected values, then the patch’s interpretation is checked in the scene. Receiver opening, closing and restart are also checked with data arriving.

Interaction checks use the application’s actual input path for selection, framing, picking and libraries. They also check that 3D selection preserves DMX levels. A separate Ethernet check connects the physical CM4 to the PC; results from loopback and from the physical connection retain their respective scopes.

Repeating the same inputs makes versions, profiles and behaviours comparable. Validation for an installation is completed on the target hardware, the intended network and the reference fixtures.

Custom tools for your product

The same approach applies to scene editors, installer panels, configuration tools, rig visualisers and test applications. Development connects the device model to both the protocol and the tasks the operator needs to perform.

Silicon LogiX develops custom software for manufacturers and integrators: product-branded interfaces, fixture profiles, project files, diagnostics and links to the electronics. Requirements define universe count, source handling, saving workflows and behaviour under fault conditions.

For a lighting desk, a stage rig or an installation, software is designed around the data path: who generates commands, who receives them, how they are interpreted and what should happen if the connection drops. Interface, hardware and protocols are developed as parts of the same system.

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