An active DMX splitter can be implemented in several ways. The simpler ones are lower in cost, while the the more complex ones offer greater protection. They all share the same basic principle of buffering (often called regenerating) the DMX data stream however.
The splitter topologies below are all active types. Passive splitters (no electronics) are not allowed under the DMX standard. This is because each DMX data cable segment should only have two ends. See the related section for more information.
This is the most basic type of active DMX splitter. The incoming DMX stream is buffered and each output is a buffered copy of the input. There is no isolation between the input, the outputs and the power supply. Minor damage caused by static electricity or lower levels of voltage applied to the input or outputs will usually result in the associated chip being damaged. Faults that apply high energy to the inputs or outputs can easily travel through the input and other outputs, causing widespread damage to connected equipment.
The next type of splitter isolates the input. This offers some protection. A fault voltage applied to the DMX receiver chip may well damage it and the associated circuitry, but is unlikely to propagate to the outputs, as the receiver's power and data lines are isolated from them. However, faults that apply high energy to an output can easily propagate to the other outputs and cause widespread damage to connected equipment.
This type of splitter isolates the individual outputs. This offers more protection. A fault voltage applied to the DMX receiver chip may well damage it, the associated circuitry and the power supply, but is unlikely to propagate to the outputs. Faults that apply high energy to an output are unlikely to propagate to the other outputs or the input. Damage is usually limited to that output and any equipment connected to it.
This splitter type offers the most protection. The input and each output are all individually isolated from each other. Minor faults usually result in damage to just that input or output. High energy faults on the input or any output are unlikely to propagate beyond there.
The type of active splitter you need to use depends on the application. If all DMX devices are in the one local area, ground potentials are the same and faults are unlikely, a non isolated type may be all you need. Larger DMX networks spanning buildings and power sources will benefit from an isolated design. DMX networks with expensive equipment connected may dictate a fully isolated design to minimise the risk of widespread damage if the worst should occur.
Categories: DMX Information pages