DMX over Ethernet

[jowens]

You have a valid point. Back when I was in high school, we had a fresh renovation (completed half way through my Freshman year) with motorized battens. It was great not having to worry about adding and removing weights whenever we'd do a new hang, but the kids at the cross town rival school were way ahead of us in educational regards because they had a counterweight system. Their school was relatively new, having been built in the '90's. Our technology and overall space was better, but they learned more rigging fundamentals than we did. Sure, there's always college, but some people don't go to college and instead choose to go straight in to the field. In their case, it would be nice to have learned the basics in high school rather than out on the job where time is money.

Hydraulic orchestra pits are nice, but are they necessary in a high school where it will only get used a couple times a year?

I tend to disagree. While the building I teach in has some great stuff, it is certainly not spectacular in its backstage capabilities (i.e. no motorized battens, no motorized pit, etc. etc.). The thought that a public school should not be progressive when given the opportunity is unfortunate, and not what the schools need.
I work hard to spend our limited budget to improve our space, just as many of us do, here on CB. If given the opportunity to offer my students and community a substantial upgrade and more of a space to be proud of, you bet I'd lobby to get every last thing (dollar) I could.
If a student comes out of a school only with the knowledge of how to operate their single piece of equipment, the teacher failed. What I love about teaching theater and theater tech is helping kids to become problem solvers, regardless of the equipment at hand. So many other places in the school teach kids to get 'the right answer' in the 'prescribed algorithm.' My kids learn concepts that will guide them regardless of the system used.

You can't fault a student whose community made an investment in their theater (often times, big jobs like this come in the form of community votes on a bond issue) and then tell him he should have worked on regressive equipment. It really just sounds like jealousy. Often times public schools work to get new materials, infrastructure, computers, facilities, etc. so that their students are prepared for the future. One of the largest 'non-educator' complaint about education is about how our kids aren't prepared for the future. I think it's more of a problem solving issue. So, if a teacher with an aging system doesn't give opportunities to problem solve, their student is no better off than that of a teacher with a state of the art system with the same teaching methodologies.

So are the advanced technologies appropriate in high school? Of course; more of the question, however, is how are teachers working with kids to help them get a thorough understanding of what they're using and maybe what they're not using.

~Joe

 

[epimetheus]

Cat 5e and up is acceptable for installation. We recommend Belden 9729 (or equivalent) for DMX because it is shielded and more robust that Cat 5, but in installation where it is run in conduit, you are not likely to see performance loss assuming it is properly terminated.

Slightly off-topic, but why do you guys recommend 9729 (100ohm impedance, foil shield) verses something like 9842 (120ohm impedance, braided shield)? The 9842 is true RS-485 cable; it's the de facto standard for RS-485 runs in industrial installations.

 

[millamber]

What the!!! Cat.5E???

What is that?!? I mean, I look at is as ethernet cable, not Cat.5E or Cat 3... someone help me out!

OK, so in as simple a form as I can make it (forgive me if I cover things you already know)...

DMX is based off of one host (console) sending data down a cable to other devices, which receive it in a daisy chain fashion. In one chain you can control up to 32 devices across 512 channels. this is known as a universe of DMX. The signal can be routed by an opto-splitter which takes in DMX and makes a number of new chains, while still holding to the same universe. A console will have anywhere from 1-4 universes onboard, depending on brand.

Ethernet protocol, by contrast, is more in the system layout than in what is connected to it. You can have ethernet jacks (RJ45) spaced all around the room. These jacks don't have a defined purpose like a DMX in connector would. They can change depending on what you plug into them. All that the jacks do is give you a way to get onto the network. They are, if you will, the bus stops where data gets onto or off of the network.

The ethernet cable (either Cat 5, Cat 5E, or Cat 6) connected to the backside of the jacks goes back to an equipment rack where it terminates into a patch panel. The patch panel then uses jumper network cables to connect to a network switch. The switch is sort of like Air Traffic Control, taking information in from one source and routing it to the proper source elsewhere in the system. It understands who is who by remembering (or assigning) IP addresses to all connected devices. An IP address is a ID tag for devices.

So, since the network simply routs information from one place to the next, all of the wiring is done in a Star type topology. All the information is sent to the switch which then sends it back out the appropriate line. That information can be any type of protocol really, allowing multiple users to talk to their particular devices, regardless of signal type. This is what ACN is, an Advanced Control Network that uses an ethernet backbone. In your case you are sending DMX information over that network.

The console is sitting directly on the network, sending channel information to the network. To get the ACN signal back to DMX, you would go through a gateway, basically a transformer that changes one type of signal into another. The gateways can be configured to start outputting DMX at any address. From there, it is DMX again, with fixtures daisy chaining off the chain. So your start address of the moving light can be 1-512 and the gateway can be configured to be any control channel, allowing you to control fixtures without having to worry about universes..

That is the basics, I'll fill in more after lunch if there are questions.

 

[Les]

I tend to disagree. While the building I teach in has some great stuff, it is certainly not spectacular in its backstage capabilities (i.e. no motorized battens, no motorized pit, etc. etc.). The thought that a public school should not be progressive when given the opportunity is unfortunate, and not what the schools need.
I work hard to spend our limited budget to improve our space, just as many of us do, here on CB. If given the opportunity to offer my students and community a substantial upgrade and more of a space to be proud of, you bet I'd lobby to get every last thing (dollar) I could.
If a student comes out of a school only with the knowledge of how to operate their single piece of equipment, the teacher failed. What I love about teaching theater and theater tech is helping kids to become problem solvers, regardless of the equipment at hand. So many other places in the school teach kids to get 'the right answer' in the 'prescribed algorithm.' My kids learn concepts that will guide them regardless of the system used.

You can't fault a student whose community made an investment in their theater (often times, big jobs like this come in the form of community votes on a bond issue) and then tell him he should have worked on regressive equipment. It really just sounds like jealousy. Often times public schools work to get new materials, infrastructure, computers, facilities, etc. so that their students are prepared for the future. One of the largest 'non-educator' complaint about education is about how our kids aren't prepared for the future. I think it's more of a problem solving issue. So, if a teacher with an aging system doesn't give opportunities to problem solve, their student is no better off than that of a teacher with a state of the art system with the same teaching methodologies.

So are the advanced technologies appropriate in high school? Of course; more of the question, however, is how are teachers working with kids to help them get a thorough understanding of what they're using and maybe what they're not using.

~Joe

True, a lot of it hinges on the way the system is implemented and taught.

It's still a little sad though when someone knows how to program movers on an Ion, yet can't run a 2-scene preset on the fly. Not saying everyone needs to learn a preset, etc, but that sometimes the "latest and greatest" sometimes aren't the best teaching tools. Though preset boards are obsolete, they are still likely to rear their ugly head for years in to the future. Oh and it's not jealousy. I graduated high school (with a $9m performing arts space) years ago. These days I work in all kinds of venues, from ratty community theatres to multi-million dollar complexes. I totally agree with your philosophy, I just don't think a high school needs a ton of movers, etc.

I think the best way high school students can educate themselves if they're really serious about their art is to volunteer at a local community theatre over the summer. Truly excelling at what you do means having a knowledge base which is vast and flexible.

 

[derekleffew]

...The Smartswitch is there to give you a large number of relays controllable by dmx. Yes, an R20 will do a similar job, but it is only 2 circuits per module, and you'd have to sacrifice a slot in your Sensor rack. The smartswitch allows for up to 48 relays per panel. Not to mention that it is less expensive than the equivalent number of R20 modules.

The other advantage of the SmartSwitch is that it can be used to provide the 208V that some MLs require, while the R20 is only 120V. Another use is to control 277V fluorescent lighting circuits.

 

[jstandfast]

With regard to Vortek systems and their like in public schools; it's useful to bear the legal system in mind. The idea that systems like this do not involve teenagers throwing stage weights around @ great height ( or being under others who are ) is mighty attactive to administators who have to worry about liability issues.

 

[fredthe]

With regard to Vortek systems and their like in public schools; it's useful to bear the legal system in mind. The idea that systems like this do not involve teenagers throwing stage weights around @ great height ( or being under others who are ) is mighty attactive to administators who have to worry about liability issues.

There are two other reasons that I've seen for these types of systems in schools... there is less structural load than a counterweight system, and they are ADA compliant.

 

[starksk]

Slightly off-topic, but why do you guys recommend 9729 (100ohm impedance, foil shield) verses something like 9842 (120ohm impedance, braided shield)? The 9842 is true RS-485 cable; it's the de facto standard for RS-485 runs in industrial installations.

From the true geniuses (including CB Member DavidNorth):

Each 9729 pair has an individual drain wire(for the common) and foil shield. Because of the drain wire and foil shield, it is much easier to dress and terminate than braided shielded cable. With a braid, you can either cut it off and solder on a drain wire or unbraid it down to a small portion of the shield. Both consule time and cause frustration.

 

[Shawncfer]

The console is sitting directly on the network, sending channel information to the network.

Okay, so on the picture I posted originally where theres the blue thing with all the ethernet cables going out of it (btw whats that thing called again?) theres two etherenets plugged in at the end seperate from all the others. I think those two would be the two light boards correct? (one black box one main stage). And so if the light boards are just in the same network, then theoretically I could move those ethernet cables around and it wouldn't matter because it's still on the same network correct? And also going by that, The ethernet outs that connect to the gateways which turn it into dmx, could I also plug my lightboard into the same ethernet input and it would still work because it's still on the network? Or are there special ethernet inputs for the lightboard? And seperate ones for DMX devices?

And that answers one question. I just don't understand whats so special about cat5 or cat5e or cat6.

Today I noticed that there wass one of the outputs (or inputs?) of ethernet labeled "Lighting Network" that the company hadn't quite screwed into the wall yet. So I tooke a look at the cabled attatched and it says CAT6... Then, we also recied a box from the company th a bunch of extensions, twofers, and other crap, including ethernet cable. But that ethernet was labeled CAT5e.. So is that okay?

 

[ajb]

the blue thing with all the ethernet cables going out of it (btw whats that thing called again?)

Dude. . . that was answered in this very thread. The answer was on the page where you typed this post. Hint: it was very close to the top of the thread.

theres two etherenets plugged in at the end seperate from all the others. I think those two would be the two light boards correct? (one black box one main stage).

Could be. If they aren't labeled you could unplug them and see what happens.

And so if the light boards are just in the same network, then theoretically I could move those ethernet cables around and it wouldn't matter because it's still on the same network correct? And also going by that, The ethernet outs that connect to the gateways which turn it into dmx, could I also plug my lightboard into the same ethernet input and it would still work because it's still on the network? Or are there special ethernet inputs for the lightboard? And seperate ones for DMX devices?

Depends on how the blue thing is configured--some ports on it might be set up to behave differently, or be disabled entirely if they aren't needed. Probably all the ports are active and operating normally, though.

And that answers one question. I just don't understand whats so special about cat5 or cat5e or cat6.

What's special about it is that the explosion of computer networking has made Ethernet infrastructure cheap and ubiquitous. Just about any electrical contractor knows how to install it or someone he can sub it to. There are tons of products out there that make it cheap and easy to implement on devices like dimmers and lighting consoles. And it can carry far and away more data than DMX ever could, more reliably. This ubiquity has also encouraged other products to take advantage of it, so for example if you have a big video element in a show, you can unpatch a couple of those UTP runs and use them to carry video if you wanted (with the right adapters). Or you use them with various other products in lieu of a massive audio snake from the stage to the booth. And you can do all of this on the same thoroughly standardized, inexpensive infrastructure with a huge degree of flexibility and room for expansion.

So I tooke a look at the cabled attatched and it says CAT6... Then, we also recied a box from the company th a bunch of extensions, twofers, and other crap, including ethernet cable. But that ethernet was labeled CAT5e.. So is that okay?

It's fine. Cat6 is preferred for higher speed Ethernet (1Gb+), but 5 and 5E will be just fine for up to 1Gb. It's common to spec up infrastructure cabling beyond what is currently required since it's so expensive to replace down the line. If you find yourselves needing 10Gb in a few years, it's easy to throw away that 5E patch cord and replace it with Cat6, and replace that blue thing with a shiny new 10Gb blue thing. . .it would be MUCH more expensive if you had to replace all of the fixed wiring, so the Cat6 is basically just a bit of future proofing.