First Step DMX

Y

Youpcoco

New member
Hello,
I am learning about DMX solutions for managing a Christmas show. I explain to you the existing and the objective and give you what I understood.
Today I have a show via two arduino mega boards. One that manages 48 relays for an on/off type animation of classic garlands. The other manages a garland of 100 Pixel LEDs. THE all driven by Vixen

The objective for next year, increased to 5000 LED Pixels. So I was told about switching to DMX.

If I understood correctly, to drive from the computer, I need this system in 1 copy.

https://www.enttec.co.uk/en/product/lighting-communication-protocols/dmx512/open-dmx-usb/

Then these small box connected to each other. On each box, can we connect 4 LED Pixel garland?

https://www.amazon.fr/dp/B09QCXW83R...nstruments&sp_csd=d2lkZ2V0TmFtZT1zcF9kZXRhaWw

If my progress is good, I would have a question =)

Thanks to everyone who replies
 
A single DMX channel would be too slow for 5000 pixels (500 kb/s). You need a total throughput of several Msps (5000 * 10 * 40 = 2Mb/s), or at least more than 1 Mb/s, so you would need at two or three DMX channels. I think that the techniques that RichieNorthcott or Mike Krebs mentioned are the best, using either WiFi or wired Ethernet to transfer data from the PC or whatever PC alternative that you want to use.

Edit: You would need several of those Entec boxes, probably three, not just one.
 
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Thank you for your return, I think there is a misunderstanding of the translation because I canceled that the DMC was one of the proposed solutions.

On the Wifi/Ethernet solution, is there a tutorial or detailed thread on this forum where I could find important information?

Thank you very much.
 
Also it looks like you might be a little confused about DMX data vs pixel data.

A DMX data stream has up to 512 channels. All DMX devices are chained together and 'see' all the data. Which channels they respond to is normally controlled by DIP switches on the hardware (or a software menu). DMX data uses 2 wire (differential) serial signal to communicate. DMX devices are therefore 'addressable'

Pixel data uses the WS2811 protocol, which is essentially a long stream of bytes with specific timing. Each device pixel receives bytes and passes them on to the next device in the chain on each timing pulse (so 3 pixels would need 9 bytes) in a shift-register like arrangement. Once the 9 bytes have been propogated an update 'pulse' causes the pixels to update. And repeat. WS2811 data uses a single wire. Pixels are 'addressable' by virtue of their position in the chain.

(the DMX forum is not the correct home for questions about pixels)
 
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Please confirm:
I am reading your statement as the whole data stream is sent from pixel to pixel. This is not what I have always been led to believe.

The WS2811 protocol sends the stream to the first pixel which strips off what it needs then passes the remainder to the next pixel down the line. This happens until the data is depleted, or there are no more pixels to send to.
The movement of the stream is via that "specific timing" you mention. Correct?

BTW - I'm in full agreement about DMX data. (Many years working in theatrical lighting/sound as my background. DMX was a game changer when it came out. No longer did we have signal cables leaving the booth to the stage for each channel being used.)
 
Hi Al

You are correct. WS281x is a consumptive protocol. Each node consumes the first 24 bits it receives and forwards the rest to the next node. The interframe gap triggers the node to return to the consumption state.
 
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