What Are DMX Splitters?

Digital multiplex, or DMX, splitters are digital network components that multiply DMX signals from one cable into several cables. These components can be small converters, rail or rack-mounted units linking cable to cables. They preserve and duplicate digital signals, effectively expanding a DMX512 standard 32-device network to greater capacities. This permits unified control over dozens of fixtures with hundreds of programmable effects in theatrical lighting systems. Splitters increase networking possibilities by not only dividing signals but also boosting them through additional daisy chains or remote cable extensions.

These devices extend network capacity by receiving input from a daisy chain, that is, a linked train of cables and inline devices, and becoming a new output source for several new daisy chains. Each of these chains can then branch into its own new daisy chains as needed. Multiple DMX splitters can also be linked together.

The outputs may also be optically isolated to protect against power spikes. This ensures more reliable performance, as each daisy chain can potentially host up to 32 fixtures, all leading back to a single control deck. Inputs and outputs typically possess sets of three- or five-pin XLR type connections.

Rack and truss type DMX splitters are designed to attach to external structures, sometimes with the use of Velcro®, safety wires, and clips. This permits versatile placements as well as faster, more flexible assemblies. Some splitters buffer and protect DMX signals with internal or external power supplies. Others may use light-emitting diode (LED) indicators to reveal power and data information. Like a splitter, a DMX merger performs a similar function, but instead merges signals from multiple lines into a single line.

Standardized by the United States Institute for Theatre Technology (USITT), DMX512 protocol ensures interoperability between DMX splitters and lighting components across manufacturers and brands. This permits innovative, creative arrangements for lighting networks, as equipment and fixtures are limited only by their maker's developments. The technology is also designed to accommodate technical advances and new product developments. Splitters also preserve signals more reliably than other components.

In networks using multiple power sources, or digital and lighting components that are far apart, signal transmission can be enhanced by using opto-isolator type splitters. Differing ground voltages can create current crossover and signal error or equipment damage. Optical isolation benefits larger networks by protecting the main system from devices that should be isolated. Devices can be linked at any point along a network, making possible interferences between signal loads and cable runs. The compounding of lines through DMX splitters can introduce interferences along signal cables, which are typically run off floors and separately from power lines.