OLA DMX Control lighting

[anshul mittal]

I am writing OLA based linux Qt application to control lighting. I am controlling RGB, Intensity, Blackout, All set. I have few questions as follows.

1. How can i create a buffer from the requirements above? I mean how can i get information like which bytes are for RGB and intensity. 

2. Do i have to purchase some device to use the example https://docs.openlighting.org/ola/doc/latest/dmx_cpp_client_tutorial.html. I am mainly designing my program using the above example and dont know if i need to use some device which interfaces with computer.

3. What are the universe numbers? Can i use only 1 universe number for sending all DMX data? I have 8 faders and 8 lights which are controlled by these faders.

4. There is no documentation on constructing buffers to send via OLA. Can you guide on same?

[E.S. Rosenberg]

Hi Anshul,

DMX is a very simple protocol - a stream of 25-513 bytes where each successive byte after the first (the start code) represents a "channel".

Moving lights/RGB lights etc just assign a different interpretation to what to do with these bytes (when they are configured to respond to a set of them).

Op di 12 jan. 2021 om 16:26 schreef anshul mittal <anshu...@gmail.com>:

I am writing OLA based linux Qt application to control lighting. I am controlling RGB, Intensity, Blackout, All set. I have few questions as follows.

1. How can i create a buffer from the requirements above? I mean how can i get information like which bytes are for RGB and intensity. 

The way you implement it on your application side is entirely up to you, fixture manufacturers usually provide a mapping of how they're product is controlled ie. channel 1 represents R, 2 G, 3 B in the most simple of RGB pixels, sometimes they will have a separate intensity channel, sometimes you will have to virtually compute it and adjust the RGB values accordingly.

2. Do i have to purchase some device to use the example https://docs.openlighting.org/ola/doc/latest/dmx_cpp_client_tutorial.html. I am mainly designing my program using the above example and dont know if i need to use some device which interfaces with computer.

That depends what your end goal is, if you want to control real life DMX devices you will need some device to actually put a DMX signal on a DMX wire.

If you are just trying to show that you can make OLA want to output and change values or change a visualizer screen then you probably don't.

3. What are the universe numbers? Can i use only 1 universe number for sending all DMX data? I have 8 faders and 8 lights which are controlled by these faders.

A universe is a physical DMX network, one universe can hold up to 512 channels.

Based on your questions I would strongly suggest you read up more on DMX/RDM, there are some excellent resources out there some good books I read in the past (in no particular order) -

Practical DMX, Nick Mobsby

Recommended Practise for DMX512, Adam Benette

Control Freak, Wayne Howell (If you also want to understand RDM)

In the past the wikipedia entry about DMX512 was also extensive and good (I contributed to it a long time ago, can't promise it has not been edited into oblivion).

HTH,

Eli

4. There is no documentation on constructing buffers to send via OLA. Can you guide on same?

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