Is it true you cant have more than 32 devices on 1 universe

[bretk]

I heard that in a DMX universe you can not have more than 32 devices connected together. Anybody know if this is this true?

[geronc]

per Wikipedia...... http://en.wikipedia.org/wiki/DMX512

DMX512 is a bus network no more than 1,200 metres (3,900 ft) long, with not more than 32 devices on a single bus. If more than 32 devices need to communicate, the network can be expanded across parallel buses using DMX splitters.

Just means you need a DMX splitter after 32 devices.

[geronc]

geronc wrote:

per Wikipedia...... http://en.wikipedia.org/wiki/DMX512

DMX512 is a bus network no more than 1,200 metres (3,900 ft) long, with not more than 32 devices on a single bus. If more than 32 devices need to communicate, the network can be expanded across parallel buses using DMX splitters.

Just means you need a DMX splitter after 32 devices.

Can't edit... forgot this part. I have a couple of these. They work great. They no longer make this one, but are currently revising it due to the transformer being End of Life.

http://diylightanimation.com/index.php?topic=357.0

[-klb-]

There are also a lot of devices that are 1/4 load, or 1/8 load so they can do 4 or 8 times the standard limit.

[Ken Benedict]

I've used this DMX splitter several times with great success: http://www.ebay.com/itm/DMX-Splitter-1x4-Optically-Isolated-SLIM-PCB-DMX512-/270669664842?pt=LH_DefaultDomain_0&hash=item3f052b524a

[bretk]

If I have to get a splitter and power supply, why not just get another enttec open and add another universe? Enttec open $57 from sirs-e including shipping vs $49 + power supply+case for splitter. agreed it would allow 4 runs, but i think for my application that wouldnt be an issue.

[WilliamS]

Even on that for 30 bucks you can get the USB485 from LOR and have another Open DMX universe. To have more than 32 on a single universe you muct be running or planning a ton of those 3 channel monsters.

[bretk]

William,

With a 16 ch Spiral, 8 Megaballs, couple rgb stars, 4 rgb strips, rgb holdman star, rgb spinner, rgb floods and the Firesticks I am over 32 controllers. Nothin like jumping in with both feet :dude:

[WilliamS]

bretk wrote:

William,

With a 16 ch Spiral, 8 Megaballs, couple rgb stars, 4 rgb strips, rgb holdman star, rgb spinner, rgb floods and the Firesticks I am over 32 controllers. Nothin like jumping in with both feet :dude:

Both feet head first into the shallow end of the kiddy pool! Impressive start man. Hat is off to you as 32 channels is where I started and you started with that many controllers. Cant wait to see the fruits of your labor.

[Ponddude]

The only way around the 32 device limit is to add in some sort of splitter that amplifies the data line. We have a splitter that will be in the presale tomorrow which will be useful with all our lights. The basic problem comes in here...lets take the Rainbow Flood Extreme for example. It is a 5 channel light with at the 32 device limit is only 160 channels. That leaves 352 channels still available in the universe. If you use a splitter it will allow 32 devices on each port. That is the only way around the 32 device limit.

[JonB256]

There is nothing magical about 32 devices. If you use 16 Channel boards (sound familiar?), then 32 devices is 512 channels. There are only 512 channels in a universe.

But - if you are using 3 Channel devices, you can certainly go over 32 devices in a universe. While that technically would allow 170 devices (512 divided by 3), you probably would have trouble. Each device you connect drops the signal strength slightly. If your cable runs are long or you have 40 or 50 or 70 devices, your signal strength at the end may be too low.

But it isn't because you exceeded 32.

[GaryMartin]

Correct. IIRC, David Moore used about 80 of the small 3 channel devices on a *single* universe last season.


JonB256 wrote:

There is nothing magical about 32 devices. If you use 16 Channel boards (sound familiar?), then 32 devices is 512 channels. There are only 512 channels in a universe.

But - if you are using 3 Channel devices, you can certainly go over 32 devices in a universe. While that technically would allow 170 devices (512 divided by 3), you probably would have trouble. Each device you connect drops the signal strength slightly. If your cable runs are long or you have 40 or 50 or 70 devices, your signal strength at the end may be too low.

But it isn't because you exceeded 32.

[-klb-]

As mentioned above, the RS485 standard does say a max of 32 devices. But since then, almost every RS-485 chip manufacturer has developed 1/8 load device, so you could in theory go to 256 devices. I've run 40 LOR boxes on one network in the past. No issues. Clearly a violation of 32 boxes on a RS-485 network, but they use 1/8th load chips. For reference, the limit is mentioned in the quick spec box at the top right of the wikipedia page.

http://en.wikipedia.org/wiki/Rs485

Also, as of a couple years ago, nearly every RS-485 chip spec/app note sheet had reference to the 32 node limit, and that by being 1/4 or 1/8th load that you could put more on a network..