Wireless DMX conundrum

[cedd]

I suspect, as Don has suggested, that your start address is wrong. As you've mentioned that you don't know what fixture addressing means, I'll try to explain;

 

DMX is simply data being sent down an XLR cable. It carries 512 control channels, each of which can be set at an intensity from 0 to 255. In its' simplest form this would mean you could operate up to 512 single channel dimmers, being completely off when their own individual channel is set to 0, and being at full intensity when their channel is set to 255, or dimmed anywhere in-between. There are actually very few single channel dimmers out there in the real world (they tend to come in boxed of multiple ones) but it helps with this description. Each of these dimmers of course needs to know which control channel it's going to listen to. In order to do this we need to tell it its' channel number (more commonly called its' address). This can be done in a number of ways on different fixtures, but it's mainly through dip switches (used in binary style to give any channel from 1 to 512 with only a small number of switches) or an LED display and some up/down/menu buttons on the device. Also to make it easier, imagine that the control desk for this has 512 separate faders, each corresponding to a channel (they don't exist in real life - often they'll have only a few faders that can be assigned to different channels, but it makes the explanation easier)

 

DMX isn't just used for single dimmers though, it can also be used to control just about anything - smoke machines, LED pars, moving heads etc.

 

These devices (particularly LED pars and moving heads) use up more than one control channel each. For instance a really simple LED par may have 3 channels - channel one would most commonly be red, channel 2 green and channel 3 blue. Again we'd set an address when connecting this to a DMX system, but this address would be the start address - the number of the first channel of the 512 available that we want the fixture to respond to. If we set our simple LED par to, say, channel 10, then pushing up channel 10 on the DMX controller would bring up the red colour. Channel 11 would bring up green and channel 12 would bring up blue - 3 consecutive channels starting at 10.

With that in mind, and to use this same example, if you were to get your start address wrong and set it to 9, but still pushed up channel 10 on the controller expecting it to be red, it would actually be dimming up the second (green) channel of the fixture (because the first (red) channel is actually 9) so you can see that you'd never see red working - all the functions have shuffled "left" by one fader.

 

Step this up again and look at a moving light - clearly it only has one dimmer channel, but it also has pan, tilt, colour and maybe gobo, focus, prisms..... the list goes on. 20 odd control channels per fixture isn't uncommon. Some have hundreds - it just depends on the complexity of what it allows you to do.

All fixtures should come with a DMX chart showing their various channel functions. One for an led moving head wash might for instance look like;

 

1 - pan

2 - tilt

3 - dimmer

4 - red

5 - green

6 - blue

 

In this instance if we set its' start address to 10 and then wiggled fader 10, we'd see the fixture spin around. Channel 11 would make it tilt, 12 would make it dim up - etc. At its' simplest we could use our huge 512 fader desk to position each light manually using just the faders, then set their colours and intensities. Of course this is really clumsy and isn't the way it's done - the faders for these functions are replaced with wheels, buttons, encoders, whatever the manufacturer of the desk decides to use. Often just the intensities are left on faders. This involves some intelligence in the controller - being able to tell it what fixtures you are controlling so it knows what channels to assign to what encoders. That's probably getting a bit ahead of ourselves for the time being though.

 

Lots of LED pars have more than just the 3 red, green and blue channels (in fact, most do). Lots will have red, green, blue and dimmer. In this instance the first 3 channels would be used to mix the colour, but no light would be visible until you brought the dimmer channel up. Others may have extra functions assigned to a channel, like strobe something less descript like "control". In a lot of these extra functions the fixtures split the control channel up in to chunks. For instance it might say if the channel is set to an intensity between 0 and 100, it'll strobe, getting faster as the number gets higher. Then 101 to 150 might set it in to sound to light mode. 151 to 200 might tell it to do something else..... you get the idea.

So you need to understand what your fixtures are doing and this should become clear from the user manuals where I'm sure you'll find a DMX chart.

 

You can have more than one fixture on the same address - for instance if I had a set of 4 LED pars but I only wanted them to all match each other all the time, I could set them all to the same address. The thing you mustn't do is overlap fixtures. So if I had a 5 channel LED par (1 - red, 2 - green, 3 - blue, 4 - dimmer, 5 - strobe) and set it to address 1, then set another of the same type of par to address 5, then bringing up fader 5 would make the second fixture go red, but would also make the first fixture strobe because they're both the same channel. The second fixture would need to start at 6 so they didn't overlap.

 

I hope that makes sense and perhaps explains things a little better.

[rocklander]

Where in NZ are you?

 

sorry.. for some reason I don't think I've got the hang of notifications on this board either.. bit embarrassing for a computer geek

I'm in Rotorua.

 

 

 

If you are trying to get led pars going with DMX and the colours dont match up, try moving your DMX start address up or down by 1 as a quick check. Sometimes the DMX chart in the handbooks is not correct, sometimes my I make a mistake creating a profile for the fixture and the quickest test is to change the fixture DMX address.

 

I fyou are trying to gel fixtures working and it seems to be a timing problem, see if you cam borrow a DMX merge as the one I have can change the DMX timing, which is usefull for the odd fixture that does not want to work. Probably not practical for your setup.

 

Have you contacted the supplier of the led pars ? as sometimes they are interested in feedback to improve their product, but most sellers are not, regretfully, they are just salespersons.

 

I tried it in the shop and don't really want to mess them around asking them to unpack and repack the unit again - and to be honest it was almost an academic test more than anything. the unit is still probably too large to fit on many of the pub stages we play, and I'd have to set up some reasonable cable lengths to an external switch, even then it'd be a matter of paralleling a micro switch or two.. it'd all get a bit 'band aid solution'. so I'll probably stick with what I have unless I decide to purchase some better quality par that I can be certain operate over the wifi.

as for contacting the manufacturer... aliexpress seller? not sure they'd care too much.but thanks for the suggestion :-)

[alistermorton]

It may not be a matter of a better quality PAR being able to communicate over wireless - it's just as possible that a very well respected manufacturer will use a non-DMX protocol to master-slave their fixtures in auto mode as a low cost manufacturer.

[Tomo]

It's practically certain that that all Master-Slave modes from any manufacturer will deliberately avoid using DMX for this.

 

This lets the "slave" fixture tell the difference between Master-Slave operation and DMX-controlled operation, completely avoiding the issue of DMX addressing and modes.

- It's probably just an alternate start code.

 

Also, if it was standard DMX and you happened to have some other manufacturer's fixtures connected in the Master-Slave chain, those fixtures would go randomly nuts in a completely unknowable way.

Whereas by using 'proprietary' communication (probably an alternate start code), compliant 3rd party fixtures will simply ignore the Master-Slave communication.

There's actually (at least two) ESTA/ANSI published start codes intended for this type of thing.

[rocklander]

so, when I say "master/slave" I'm talking figuratively.

what actually is set is the first can (or the foot switch, and in the shop test as well) is set to 'sound auto' (or each device's equivalent)

the cans are then set on DMX A001.... so not 'slave'.

it was in that configuration that the DMX desk and the lights worked mostly, except red colour.

[Tomo]

what actually is set is the first can ... is set to 'sound auto' (or each device's equivalent)

That's "Master/Slave" mode, which automatically means that DMX cannot be used at the same time.

 

Do not mix "Sound/Auto" modes with a real DMX controller, this will not work and will cause problems.