Wireless DMX vs Artnet over WiFi

[TomHoward]

Hi

I am looking at a way of getting DMX onto some moving bars. We have recoiling power on the bars and I’ve looked at installing slip rings but it’s a lot of cost and a wireless DMX system could be usable in other deployments.

 

I’m looking at City Theatrical (either Showbaby or Multiverse) but wondering if there is an alternative in pushing WiFi to the bars and using something like this Thomann interface, or the SmartShow one for £55.

Most of our consoles output artnet now so it wouldn’t be too much more effort - and the city theatrical units both run on 2.4G WiFi, so aside from the antennas there isn’t much technical difference. We would have to buy a decent AP to pair up with the WiFi artnet nodes.

 

Is anyone using artnet over WiFi as an alternative to 2.4G DMX now, and any pitfalls?

[timsabre]

If you really must go wireless I would stick with a proper wireless DMX product.

 

Artnet over wifi can be a bit flaky at the best of times, I've had some weird routing problems happen as well as general jerkiness and lost packets. And once you get the room full of audience with phones it can all become very marginal. W-DMX on the other hand seems pretty much immune to all that stuff as long as you get the transmitter somewhere sensible - though I haven't used those City Theatrical ones, just the Wireless Solution ones which are not WiFi.

I have also seen some good cabled DMX solutions for lifting bars involving collapsing zig zag wires (there is probably a name for this) or coiled wires dropping into baskets. And you know what they say, you can't beat a bit of wire for reliability...

 

[maeterlinck]

Wireless Solutions (wDMX) is very good. City Theatrcial is also good, but not quite as robust - plastic vs metal cases.

Newer wDMX can use 2.4, 5.2, and 5.8GHz so helps to stay away from interference.

 

Concertina baskets (Tim's zig zag wires) are a simple solution. DMX reelers aren't too expensive however. Would be less than a wireless system.

 

DMX over Wifi can give latency issues as network packets aren't time critical in the same way as DMX frames are.

[TomHoward]

The newer City stuff is metal box and looks better than the Showbaby but it’s still 2.4G.

 

I’ll have a look at the wDMX stuff also. I haven’t found much in the way of retractable DMX / balanced line reels, would appreciate any pointers.

 

The City stuff is 2.4G WiFi based, are they using a different network protocol then to improve latency?

[themadhippy]

I haven’t found much in the way of retractable DMX / balanced line reels, would appreciate any pointers.

 

https://www.jcjoel.com/consumables-category/cable-management-fibre-optics/

 

they also do the ziggy zaggy thingys,although they call em flip flop trays

[TomHoward]

The flip flop / ziggy zaggy things wouldn't work too well, as the hoists and cable reels are above a ceiling in the roofspace, with the wires and cables passing through the roofspace and down, so it's all clean below the roof in a ballroom style.

 

Do you know what, thinking about that roofspace has just got me thinking, I bet I've got half the fall of the venue in that roofspace, so I could probably make an arrangement with DMX cable going up high over pulleys with a weighted pulley in the loop that would fall and take in the slack when the bar went up. It'd be an absolute bodge but it'd work.

 

I'm still interested in wireless wDMX vs Artnet over though as we're thinking of buying some wireless boxes for use in other setups anyway. Is it right that the wDMX boxes based on 2.4G probably use a modified protocol to improve latency?

[timsabre]

So there's a standard called W-DMX which as I understand it is the Wireless Solutions product. That's in the 2.4ghz band but not on wifi channels or using wifi protocol. I'm not sure about the City Theatrical units, they say they are on wifi channels but reading the blurb I don't think they are using wifi protocol either. Unless you know different.

[TomHoward]

I just kind of made the assumption that being in the Wifi band they were using the same protocol. The Stairville branded unit using the Wireless Solutions protocol is only the same price as the Stairville WLAN Artnet unit that's worth a look.

There's also complications I guess with running multiple Artnet nodes with some of the simple lighting controllers as well, that mean you're going to have to use broadcast artnet as well and add latency further.

[dosxuk]

Important to remember these devices aren't in the WiFi band, they're in one of the ISM (Industrial, Scientific and Medical) frequency bands, allocated for non-telecommunications use of RF. Microwave ovens use the same band, and they're certainly not the same protocols as WiFi!

[timsabre]

Well I don't think that's correct, the City Theatrical units say they are on wifi channel 11. There are lots of other wireless protocols running in the same band as wifi such as zigbee and others using the 802.15.4 standard.

[Tomo]

The City Theatrical units are 2.4GHz but they are not WiFi. They aren't 'channel' 11 either, they're frequency-hopping spread spectrum over a user-selectable range.

- The idea being that you can pick a set of bands that aren't in use where you are.

 

W-DMX and Lumen Radio devices are similar, each with their own secret sauce. There are no standards here, only modules you can buy/licence.

 

Bluetooth is also 2.4GHz, as are most wireless headphones.

 

The frequency has nothing to do with the protocol.

[TomHoward]

I don't think it's clear cut, the original Show DMX seems to operate in wifi, the current Show Baby 6 operates "in the general area of" channel 14 which is the industrial band. However the new stuff then seems to hop over the entire 2.4GHz spectrum (inc channel 14, which means it 'should' outperform Wifi ideally as that shouldn't be up in 14) but may mean it performs at wifi levels, unless they've made a protocol which is happy to compliantly work alongside wifi but ignore the packet switching.

 

I've got wired nodes & a few domestic routers already so I might set up a shonky bridged Artnet route over WIFI and a direct DMX line out the desk to two fixtures and see if there's any real world latency.

[timsabre]

Also test with 100 punters and phones for the full effect...

[strand600X]

We use 3 x show baby's in our 1600 seat venue and have had no problems with them at all.

They run Robe 150 beams, color source pars and color source profiles. No latency at all it's a good bit of kit, yes plastic box but installed it works really well.

 

bAz

[maeterlinck]

2,4GHz is a licence free bit of spectrum allocated for open use worldwide. As James said it's part of the ISM set: https://en.wikipedia.org/wiki/ISM_band

 

Lots of devices use the bit of frequency range, from WiFi, to cordless telephones. (https://en.wikipedia.org/wiki/List_of_2.4_GHz_radio_use).

 

Silicone (chip) makes make general use radio chips that work on this band as well. They can be used to do wireless monitoring of buildings, run wireless home or office devices, or transmit data wirelessly - like DMX.

 

The wireless DMX manufactures use these radio chip to do the OTA (over the air) bit of their systems. City use devices by Microchip, wDMX and Lumen use Nordic Semi. The 'secret sauce' or protocol is how they deal with forming the packets that are sent to the radio, and how the receiver deals with missing packets. And of course how good the radio layout is - which can be an issue with the cheaper devices as they will often use reference designs meant for basic implimentation.

 

WiFi is a stack of technology that specifies the protocol and how the protocol is transmitted over the air. It is generally aligned around a middle frequency. For user ease the 2.4Ghz range was split in to bands - 13 of them. And most WiFi will be found at 1, 6, or 12. Most modern wireless DMX systems are spread spectrum frequency hopping, meaning they transmit consectutive packets on different frequencies is a set 'hop pattern'. This helps to reduce interference from other devices. Some like wDMX add an adaptive element to 'hop' in areas of less interference.