led fixture and DMX connecting???

[godd2]

Hello,

 

I am thinking about buying a few simple led par 56 units that utilize 5 channels. my problem is how do I get the DMX cable to the control consol. I have spoken to one person that said I simply connect each unit with shorter DMX and then off the last unit take that one to the dimmer rack back stage which then can be controled from the lighting consol. then I speak to another person that tells me that led light cant go through a dimmer rack and has to go directly to my consol, which is obviously at the back of the house and much further away.

 

can anyone tell me how this is suppose to be done?

 

Also if each unit chained together are they still able to be independantly run?

 

thanx for your help,,,this is stressing me out!!!

 

if I can figure this out and the whole smoke/haze issue I will be sitting great!!!!

[DMXBandit]

Are your console and dimmer rack controlled by DMX, and are they already wired together? If so then the chain will go Console > Dimmer > LED > LED etc.

Also if each unit chained together are they still able to be independantly run?

The DIP switches on the back of the LED cans allow you to set independent addresses for each fixture. You will have to check the instructions that come with the LED cans as there are many variations out there.

[norty303]

If you wish to control DMX devices (DMX dimmer packs, moving heads, LED units, etc) then they all need to be connected together in a chain coming out of your control desk, and passing through each unit. The order in which you connect them is unimportant (although some people like to have LED's on a separate universe or use a DMX splitter to run logical groups for easier trouble shooting)

 

No intelligent light should be connected to dimmers (generally), they should have their own separate hard power. So you will need hard power into your dimmers and to each LED fixture, and then a DMX signal chain running to each. Don't forget to terminate the last fixture in the DMX chain if it doesn't already have automatic termination.

[Robin Pratt]

Are your console and dimmer rack controlled by DMX, and are they already wired together? If so then the chain will go Console > Dimmer > LED > LED etc.

 

.....however it is not unknown for LED products and dimmers to fight when on the same chain, it would be better practice to use an active splitter. This can be located at the stage end of your long DMX run, just before the dimmers. It would also be good practice, though rarely essential to fit a terminator on the end of each line. So, the chain will go....

 

Console > Active DMX splitter input

Splitter output 1 >dimmer > dimmer > terminator

Splitter output 2 > LED > LED > terminator

[godd2]

Are your console and dimmer rack controlled by DMX, and are they already wired together? If so then the chain will go Console > Dimmer > LED > LED etc.

Also if each unit chained together are they still able to be independantly run?

The DIP switches on the back of the LED cans allow you to set independent addresses for each fixture. You will have to check the instructions that come with the LED cans as there are many variations out there.

 

we do have DMX that goes into the consol. I dont know the name off the top of my head but it is a levitron or something like that..colortran pretty much..about 3-4 years old. it has the capability to run intelligent fixtures so I think I am ok. I am somewhat concerned about the dimmer rack since it is like 15 years old I believe...so if that is a prob I guess I would have to goto the consol directly correct?

 

thanx

[Wol]

For terminologies sake, DMX should come *out* of the console as the console *transmits* the data along the DMX cable to the other fixtures, rather than receiving it.

 

Also, I think the difference between the two people you mention in your first post, is that the first one is talking about the data / DMX connection, which gets daisy chained, and the second one is talking about how to power the actual LED fixtures ( it's a fairly good assumption that you cant run a LED parcan off a dimmer! ). Reading through some of the other posts also it hasnt appeared amazingly clear either! The data gets daisy chained from one to another: Console > Dimmer pack > LED > LED > LED .... . All of the devices then plug into mains power somehow. And then you plug lanterns into the dimmer pack.

 

Hope that makes sense!

 

Robin: I've never personally had problems with sticking LED fixtures on the ends of the DMX chain from a dimmer pack, and thats with a variety of the smaller 6 channel portable dimmer packs. What do you mean when you talk about them "fighting"? Unless you have the LED parcan set into some form of master mode for a master/slave operation, rather than in DMX control mode then I can imagine them not quite working.

[Robin Pratt]

Robin: I've never personally had problems with sticking LED fixtures on the ends of the DMX chain from a dimmer pack, and thats with a variety of the smaller 6 channel portable dimmer packs. What do you mean when you talk about them "fighting"? Unless you have the LED parcan set into some form of master mode for a master/slave operation, rather than in DMX control mode then I can imagine them not quite working.

 

I've never had a problem with "proper" LED fixtures like Thomas, Pulsar etc. but some of the cheap far eastern import LED PARs I've used seem to have very poor isolation/ buffering on the DMX line and introduce noise or reflections onto the chain causing the dimmers to glitch and flicker. Admittedly my diagnosis was by trial and error rather than measurement, but after changing cables and terminators one by one an isolated splitter was the only thing that cured the problem.

 

Also depends on the number of devices on the chain, I vaugely recall the spec for DMX suggesting no more than 32? devices per chain, although I'm very much open to correction on that point...

[Wol]

32 devices, one of which is the controller: Which as far as I know comes from the RS485 (?) spec.

 

Practice, if I can whenever I'm working with 'cheap' LED pars is just to keep them on their own universe so they can screw each other over, but not more critical fixtures! heh.

 

To the OP, out of interest, what did you mean when you mentioned the smoke/haze issue in your original post?

[niclights]

To the OP, out of interest, what did you mean when you mentioned the smoke/haze issue in your original post?

http://www.blue-room.org.uk/index.php?showtopic=36679

[Wol]

Ah okay! Thought I was starting to go a bit (more) insane and that I'd missed something there!

[matt c]

32 devices, one of which is the controller: Which as far as I know comes from the RS485 (?) spec.

 

Quite correct, and should be used as the basic assumption when setting up a network.

 

The figure comes from the input impedance of the receivers used, and is commonly referred to as a unit of load.

 

There are 1/2 and 1/4 load receivers which will allow you to add (subject to other receivers and limitations on cable length etc...) up to 127 receivers on a line (the other being reserved for the master).

 

If you do happen to put too many units of load onto a bus, best case is the differential voltage will drop too low, and make transmission impossible. Worst case is you overload the driver, which then fails completely, sometimes with a cloud of smoke. :)

 

Also remember that the input to a splitter / repeater is a load on the bus too.

 

Matt