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node-dmx / dmx

DMX controller library for node.js
MIT License
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Multiple DMX512 Decoders #82

Closed cc-greglorenzen closed 4 years ago

cc-greglorenzen commented 5 years ago

This may be a question more related to how DMX works in general, rather than how the library works, so I apologize if that's the case, but how do the channel numbers work when using multiple DMX decoders daisy chained together? Do they just increment until the max 512 channels are reached?

wiedi commented 5 years ago

You assign each device (decoder?) an address (channel) on the bus. This is often done using dip-switches or small buttons.

You can assign multiple devices to the same channel and they will behave the same way. Some devices can use more than one channel (for example three channels for red, green, blue) so you have to take care that these don't overlap.

The channel assignment is independent of the cabeling or the order in which the devices are placed on the bus.

The channel is just the byte position in the channel data of the DMX frame. So if your decoder wants to know what value channel 7 has it will just look at the 7th position.

I hope this is an answer to what you're asking.