One Arduino - two DMX Universes..... advice please.

Projects General Guidance
1

Pribably the esiest way to start is to explain what I would like to do

I have a mobile disco setup,my central lighting gantry consists of six Acme Dynamic 25 LED units all DMXed together. These units (two scanners, two barrel rollers, two spinners) have a built in funtion whereby they all work together withut a DMX controller to produce a synchronised lighting show. One of hte lighting units becomes the 'Master' to operate all the others together

Now I also have two lighting tripods which I used alongside my central gantry for larger venues when I need more powerful lighting, on each of these I have two iShow4 'moonflower' lights and one Martin Wizard barrel roller. All of these are also DMX and I run them in with an DMX controller which allows me to select the colour/gobo manually, but still use the inbuilt sound-to-light feature to control the rotation/movement.... so far so good

Now what I want to do is to use an Arduino to monitor the DMX traffic on my main gantry and when it sees the commands to select colours/gobos (I know the DMX address/values for each colour/gobo) I then want to automatically generate a DMX command sent to my iShow/Wizard lights so they also select the same or similar colour/gobo at the same time, thus synchronising the whole light show

Now I do have some idea how to do this from a bit of googling - it would seem I need two DMX shields, as you can only have one master in each DMX 'universe' - and I need sheilds that provide optical/galvanic isolation.

Here is where the questions start.

Have i correctly understood/identified the method I need to use to implement this?

Can I just stack together two commercially available shields, and if so how do I make sure that one is only recieving data (Slave) and the other is only sending data (Master)?

Can I use/configure one of the readily available DMX libraries to talk to two differnet shields like this and have two separate DMX universes on one Arduino?

Would I be better building my own hardware/shield? (I am very experienced with electronics)

Is there some better way to handle this project eg: some 'off the shelf' solution that I should use instead?

Cheers
Rich

2

hi.

i do also know allot about DMX.
your talking about 2 universes but in the END its just one. if i read it correct.

you like to Pass in DMX signals -> change them(show correct color for iShow/Wizard) -> and output them again to the iShow/Wizard

you can use 2 DMX shield. but one only needs to use RX! and the other only needs TX!

so as example
if dmx.channel(1) == 45 (color RED)
Send dmx.setchannel(20, 120) color red on iShow/Wizard

this could be possible

and creating your own hardware is Allot!!!! cheaper. and you can connect everything the way you like instead of predefined pins.

3

DISCLAIMER - I've never done anything with DMX...

All of the DMX shields I've seen have an input and an output, so it should only take one shield.

"Philosophically", it's like any other microcontroller project with inputs & outputs and software to "logically connect" the inputs & outputs.

and I need sheilds that provide optical/galvanic isolation.

I'm not so sure about that. The DMX hardware protocol is fairly robust and I'd trust the shield to work, however it's made (assuming it's well designed & built).

ll of these are also DMX and I run them in with an DMX controller which allows me to select the colour/gobo manually, but still use the inbuilt sound-to-light feature to control the rotation/movement.... so far so good

So... Why can't this controller be used to control ALL of the lights? If it doesn't have the features you want, it might be better to buy or build a new master controller for ALL of the lights that has all of the features you want.

4

All of the DMX shields I've seen have an input and an output, so it should only take one shield.

yes your totaly right.

and to give you a idea.

DMX has 512 channels and each channel can have a Value of 0 to 255
a Channel can have Pan/tilt move right to left and up to down. dimm RGB leds, or a Light bulb.
and many more Features.

i'm creating my own Lighting desk with a DUE and its realy a Pain in the @$$ its not that easy.
you need to Store/create Sequences. play then back. with Speed and Fadetime.
load fixtures files so your desk knows which channel does what.
each channel can be set as HTP or LTP.

i then recommend to get a enttecPro and use Fresstyler to controll the lights.

and what dicky96 like to have is to run ONE fixture as Master and all the others as Slave.
if Fixture 1 is set to color red i doesnt mean that Fixture 2 is also set to color red.

because fixture 1 has other specs then fixture 2 and they dont know which channel does what from each other.
its a realy Dump system.

5

DVDdoug:
DISCLAIMER - I've never done anything with DMX...

So... Why can't this controller be used to control ALL of the lights? If it doesn't have the features you want, it might be better to buy or build a new master controller for ALL of the lights that has all of the features you want.

@dvddoug
You are correct - I could use my DMX controller to program all the lights - but then I have to program them all from scratch, create the sequences I want and carry with me a laptop or PC to run the dmx controller (it's an ADJ MyDMX2) plus also I have not yet found a good way to implement sound-to-light triggering via an external DMX controller.

So what I have is a set of six fixtures (The Acme Dynamincs) that will, when connected together via DMX leads, automatically create a sound-to-light display with all units synchronised together. In fact you can add more than six units in various combinations (scanners, rollers, spinners)

So because this setup already gives me a show synchronised to the beat of the music I felt it was a good option to basically monitor or 'sniff' the DMX data with an arduino, and when I detect the commands that select gobos/colours I can use the arduino to send suitable commands to my iShows and Wizzards to select a similar gobo and/or colour at the same time

Now obviously I cant just connect up the iShows/Wizards on the same DMX daisychain as the Acme Dynamics as the DMX commands they use would not be meaningful to the iShows and Wizards.

@spirit
I can understand that all the lights could be on the same DMX universe in as much they can have different addresses and would only respond to a DMX command to that address - however i was under the impression I can only have one DMX master in the universe - so as one of the Acme Dynamics is acting as a Master to the other ones, I can't also have my Arduino sending commands to the iShows and Wizards as would then have two Master devices and they would in some way conflict?

I do know for example that certain light fittings user manuals warn against having more than one Master when they are running in Master/Slave mode otherwise this would damage the lights?

This is why I thought I needed two universes, because I have two Master devices. Is that incorrect?

Since originally posting by the way, I found these links
http://www.deskontrol.net/blog/arduino-four-universes-dmx-512-library/
http://www.deskontrol.net/blog/schematic-arduino-4-universes-dmx-shield/

Would that suit this project?

It does not have any isolation though. Contrary to what is being posted here, this link (and some others) suggest that isolation is essential when running in a live environement such as a mobile disco. I would happily like to get away with no isolation though if it really is not necessary to implement it :slight_smile:

quote: 'Isolation: For a simple setup it is possible to connect the Driver chip directly to the Arduino pins but if you need a robust system, especially on a stage environment, you will have to add some more electronics to avoid electrical damage by defect equipment or accidental circumstances. The electric potential of the DMX side of the implementation have to be isolated from the processor. '

6

I can understand that all the lights could be on the same DMX universe in as much they can have different addresses and would only respond to a DMX command to that address - however i was under the impression I can only have one DMX master in the universe - so as one of the Acme Dynamics is acting as a Master to the other ones, I can't also have my Arduino sending commands to the iShows and Wizards as would then have two Master devices and they would in some way conflict?

you can have more master inside your dmxchain, but this will give a Realy crazy Show. i never broke any light beacuse there where 2 master units.

but the idea i have isnt with 2 Master units, its just one Master fixture Creating Random values(music controlled) on the DMX line.
and the Arduino will Change some Channel values so it makes more sens to other fixtures.

7

@Spirit
OK mate on that advice I will run my iShows/Wizards on a separate DMX universe as I don't want a really crazy show lol

Unless there are better suggestions I will go with that four universe DMX library/schematic

As I only want to recieve on one universe and only output on another, I don't even have to fully populate the PCB :slight_smile:

Good luck with your own project too.

Rich