DiyLightAnimation
Fun => The Porch => Topic started by: DanHouston on April 30, 2012,
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I am laying out some permanent wiring from where my etherdongle to a couple of starting points for DMX devices. What I would really like to do is come out of the etherdongle and split to 2 runs, then at the end of each of those runs use the combiner (in reverse) to break out to 4 DMX universes. There a way to do this?
I've attached a picture that shows what I think I'd want to do.
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what you suggested will work.
use a rj45 splitter, and a combiner in reverse. :)
the splitters can be obtained for a couple bucks.
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Great! I thought I had read somewhere the RJ-45 splitters would not work....Think I have a couple of those lying around.
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Would you be expecting 4 universes of DMX?
The splitter/combiner just takes the 4 sets of wires (single cable) coming out of the etherdongle and splits them out to 4 sets of Lynx compatible DMX format connections and or does the reverse.
If you are trying to split a DMX signal that requires some electronics to control the signal loading.
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I'm expecting the same 4 universes at two different locations, and splitting them before they hit the combiner (to cut down on cable runs).
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I expect problems doing this. I would run to one hub then from the active output to the other. We do not have pixelnet splitters yet but they will come.
RJ
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The reason that RJ developed the DMX splitter is that you can't send the same DMX signal to two different locations using a hardwired splitter. You ould need a Quad DMX splitter (or 4 of the DLA DMX splitters with a special hardwired cable arrangement See attached drawing.
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are the splits to go to different parts of the yard, or to go around an object (like a driveway)? If so, then yu would need an active hub in place of your splitter in your diagram. it safely splts the signal to 2 outputs, and regenerated the signal in case you have long cable runs. whats nice is if you're NOT putting anything else in this area, you can easily use an old atx power suplly you might have laying around to power it. If you MIGHT add some thigs later on, you have powered ssc outputs, AND a DMX output at this location in the yard, sso rather than just splitting, you have options.
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I expect problems doing this. I would run to one hub then from the active output to the other. We do not have pixelnet splitters yet but they will come.
RJ
No pixelnet here.
I flashed the etherdongle for DMX and have 4 universes coming out. I'd really like to send the 4 DMX universes to 2 locations. It looks like the DMX splitter here is dead? (a component no longer available)
So it looks like the problem with a hardwire split has to do with signal reflection and signal strength?
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I expect problems doing this. I would run to one hub then from the active output to the other. We do not have pixelnet splitters yet but they will come.
RJ
No pixelnet here.
I flashed the etherdongle for DMX and have 4 universes coming out. I'd really like to send the 4 DMX universes to 2 locations. It looks like the DMX splitter here is dead? (a component no longer available)
So it looks like the problem with a hardwire split has to do with signal reflection and signal strength?
If you looked at my diagram (Dual DMX Drops.pdf) you would see that not only 4 the current DMX splitters would be needed but at least 5 combiners.
RJ is supposedly going to redesign the splitter to replace the transformer but I bet it's not on his priority list.
What you want to do is potentiall a good idea for running 4 universes of DMX to two different places but there isn't a good solution today.
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Yeah I looked at your drawing, and that is with the current stuff, and my understanding is the DMX splitter is not available anymore. I am looking to split the full 4 universes coming out of the etherdongle to two other runs of the full 4 universes.
I know the "splitter" I have in my diagram is not on this site anywhere (I dont' think), so I was looking for options to achieve what I wanted to do.
Maybe I'll take this on as a project to try and learn more about circuit design....Anyone wanna help? :)
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Dan-
I'll certainly help with the design.
/mike
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RJ is supposedly going to redesign the splitter to replace the transformer but I bet it's not on his priority list.
The new splitter design is alive and well although I don't know when they will be available.
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The reason that RJ developed the DMX splitter is that you can't send the same DMX signal to two different locations using a hardwired splitter. You ould need a Quad DMX splitter (or 4 of the DLA DMX splitters with a special hardwired cable arrangement See attached drawing.
It's not DMX that is "split" - it's RS-485 and it is possible to passively split RS-485. There are some limits to doing this but I've personally split a single RS-485 line coming from an Lynx Dongle over 90 different T drops, each with a non-repeating controller. Of course there are limits and those revolve around termination, wire length, shielding, load, etc. This is an excellent article on the subject:
http://www.maxim-ic.com/app-notes/index.mvp/id/763
This may also help explain the difference between DMX and RS-485:
http://www.holidaycoro.com/v/vspfiles/downloads/DMXandLORProtocols.pdf
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Isn’t the simplest solution to just get another etherdongle and put them both on the network? In way your spliter is just a network switch.
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Probably just as cheap as well by the time you look at all the other parts necessary and the design and development needed to make it work.
KISS.
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it took Einstein to give the best solution ;D
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It looks like the DMX splitter here is dead? (a component no longer available)
And you would be wrong! LOL
The redesign and beta is done on the SSR4 and Splitter and the coop manager is inline to start his and was just waiting for the SS coop to finish.
RJ
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It looks like the DMX splitter here is dead? (a component no longer available)
And you would be wrong! LOL
The redesign and beta is done on the SSR4 and Splitter and the coop manager is inline to start his and was just waiting for the SS coop to finish.
RJ
I like to be wrong. :)
Will the splitter handle my situation? (split the 4 universes coming out of the etherdongole to 2 or more runs of those 4 universes)
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The reason that RJ developed the DMX splitter is that you can't send the same DMX signal to two different locations using a hardwired splitter. You ould need a Quad DMX splitter (or 4 of the DLA DMX splitters with a special hardwired cable arrangement See attached drawing.
It's not DMX that is "split" - it's RS-485 and it is possible to passively split RS-485. There are some limits to doing this but I've personally split a single RS-485 line coming from an Lynx Dongle over 90 different T drops, each with a non-repeating controller. Of course there are limits and those revolve around termination, wire length, shielding, load, etc. This is an excellent article on the subject:
http://www.maxim-ic.com/app-notes/index.mvp/id/763
This may also help explain the difference between DMX and RS-485:
http://www.holidaycoro.com/v/vspfiles/downloads/DMXandLORProtocols.pdf
Excellent articles. Thanks!
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Well the DMx splitters only split a single pair of DMX so not really what your wanting to do. I think the best thing is to daisy from the first hub to the second and use the splitter on the hub. I hear rumors of a tech gifted member might be planning to come up with a true Pixelnet splitter but only he knows for sure and since It is not me, I am not sure either.
RJ
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I still would vote for the dual edongle solution because the router would do the splitting. It could even be wireless with a wireless access point next to it.
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So... why wouldn't this work for short distances?
3 Way Female CAT5 Splitter
http://www.holidaycoro.com/product-p/adapter-3wayff.htm (http://www.holidaycoro.com/product-p/adapter-3wayff.htm)
Since they duplicate (split) all 4 pairs, and this works in other DMX installations -- why wouldn't this work just as well for 4-pair DMX -OR- Pixelnet coming out of the EtherDongle?
Yes, with long lengths of wire there will be fallout, but for a short 5-ft and another 100-ft length of cable it should be fine.
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Trying to avoid the engineering technobabble, it all depends on how lucky you are... The split itself is going to introduce an "impedance mismatch" in the wire which will cause reflections of the signal and distortion. If you are lucky, it won't be a problem. If you are not lucky, you will get errors in the transmitted data. Since we use one way communication, there is no opportunity for corrections to the data errors...
If you want to dig deeper, you can explore transmission lines and smith charts. However, you don't need to know any of that stuff to have fun with blinky...
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I still would vote for the dual edongle solution because the router would do the splitting. It could even be wireless with a wireless access point next to it.
Definitely a possibility.
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<md..I have to ask a question, from the ET plug in to a nec switch and use that as a splitter?
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<md..I have to ask a question, from the ET plug in to a nec switch and use that as a splitter?
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You could plug 2 ethernet dongles into a switch or router. Both dongles would receive the same communications and send the SAME DMX or Pixelnet data out of each of the respective e-dongles. It's kind of like 2 DMX devices with the same addresses responding identically.
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I have the basic design done for the pixelnet splitter. I just sent the schematic and layout to RJ to get his opinions on it; if all is well, I will send off for some boards to test the design.
It is a 3-way splitter (one pixelnet in, 3 out) and fits in a TA200 case (the same one as RJ's DMX splitter).
/mike
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I just sent the boards out for fab; I should get the protos in a few weeks. Of course, I already found a few minor issues in the silkscreen, but that's not a big problem.
/mike
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I just got the boards; now to load one and test it. Already discovered I ordered the wrong fuse holders, and that I am out of vertical RJ45s... Shouldn't affect testing, however.
/mike
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That is a good looking board.
Do you have any initial estimante on cost?
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Single piece Mouser BOM is about $35. That includes everything except the PCB, TA200 case, and power cord. Slightly lower for the 220V folks, but they will need a wallwart to power it (the transformer is not available in a 220v version - the wallwart would likely be anything in the 7 to 15v range, AC or DC, but I need to do some testing to verify that range).
/mike
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Nice job.
RJ
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Nice work!
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I'm curious... why are all the vias and pads seems to be filled with solder?
Nice work Mike
Tom
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They're not. I scanned the board on a scanner; you are seeing the white of the cover thru the holes. The vias are actually tented (covered with solder mask) on both sides; this would be an issue if the board was being wave-soldered but not a problem for hand soldering. I keep forgetting that is the default setting.
/mike
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As I was finishing the testing, I ran into an issue. The power transformer can't handle the load of the driver chips I used when running multiple outputs. I'll do a quick respin using the MAX490 chips that RJ used on the active hub, driving 2 connectors and one passthru connector like on the passive hub.
More to follow.
/mike
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Respun board has been loaded; it looks like it is working now. I have sent one out to Dan for testing. I have to nudge the transformer a tad before I release it as one of the pins hits the standoff below it, but that's a very minor tweak.
/mike
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Question from post #26.
The output of the etherdongle is 4 universes of pixelnet.
Pixelnet and Ethernet are not compatible protocols, the switch wouldn't know how to interpret the data or what to do with it...
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The board has been tested, and the coop is now open.
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Can someone give me a brief description of what this does and what you could do with it in practical terms?
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It is like the DMX splitter, except it is for pixelnet. It has one input, a passthru, and two regenerated outputs. It works like the pixelnet output of an active or passive hub without the SSC ports.
You can use it when you need to split a pixelnet run to two places and don't want to tie up a hub. It also regenerates the signals so you don't run into issues with too many pixelnet hubs or devices on a cable.
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Is the one being released different than the one in the picture? The onein the picture really looks like all three are being regenerated. I'm no questioning, just curious.
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Yes, it is different. I had to change it because the new power transformer couldn't provide enough current to handle those drivers (they are quite power-hungry).
/mike
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It is like the DMX splitter, except it is for pixelnet. It has one input, a passthru, and two regenerated outputs. It works like the pixelnet output of an active or passive hub without the SSC ports.
You can use it when you need to split a pixelnet run to two places and don't want to tie up a hub. It also regenerates the signals so you don't run into issues with too many pixelnet hubs or devices on a cable.
Could this also be used as a dmx splitter or would it only work with pixelnet data, or would that require a different version of the firmware?
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There's no firmware involved, since there is no micro on the board. I haven't tried it with DMX, but I think it would work.
/mike
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Oh, I see now. I didn't pay close enough attention to what ICs were involved. It's basically a rs485 repeater for each of the 4 pairs of pins on a rj45 jack. So it shouldn't make any difference on the data transmitted.
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Trying to avoid the engineering technobabble, it all depends on how lucky you are... The split itself is going to introduce an "impedance mismatch" in the wire which will cause reflections of the signal and distortion. If you are lucky, it won't be a problem. If you are not lucky, you will get errors in the transmitted data. Since we use one way communication, there is no opportunity for corrections to the data errors...
If you want to dig deeper, you can explore transmission lines and smith charts. However, you don't need to know any of that stuff to have fun with blinky...
Wow Smith Charts....I remember those from college! You said it well. back up a couple posts to checkout the data about RS-485 it works very well when used within the specs. I install DMX and network based DMX systems for a large theatrical lighting company. We are going away from DMX splitters and going with more DMX network nodes. It is not uncomon to have 8-10 DMX networks nodes all set to the same universe in a theatre install. The system I am installing right now has 2 24 port POE switches with about 30 active DMX or Network devices.
KEN
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There's no firmware involved, since there is no micro on the board. I haven't tried it with DMX, but I think it would work.
/mike
I've tested DMX and it works.