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DMX 3-Ch Controllers without IN / OUT

Discussion in 'RGB Lights - Intelligent Pixels and 3-Channel RGB' started by randallr, Oct 16, 2012.

  1. randallr

    randallr New Elf

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    I'm looking to build 36 RGB (dumb) snowlakes to replace my very aged ones used on my roof...


    If I use the 3-channel controllers (such as the HolidayCoro model) where there is only a single wire for DMX, do they all need to connect along a 'bus' type chain? I assume that they all shouldn't connect as a "star" type topology to a central connection.


    (I might also be better off using the tigerdmx 48 controller)


    I've used DMX quite a bit, but it's always been through XLR IN/OUT daisy chained connections.
     
  2. lithgowlights

    lithgowlights Senior Elf

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    No reason you could not connect as a star setup, with an appropriate DMX splitter such as the ones David_Avd sells (I have 2 of his in use this year, and 3 DMX Splitters in total).
     
  3. kane

    kane Dedicated Elf

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    Because DMX-in and DMX-out are generally wired up in parallel, even if there is only set of wires (gnd/dmx+/Dmx-), you can usually connect both IN and OUT to this one set.

    Ray Wu's 10W DMX Flood Lights are exactly like this, and I have connected both the DMX in and out to the Dmx wires, and connected 10+ of these floods on the one chain.

    Alternatively, you can use a DMX splitter if you would prefer a star configuration, but I couldn't see the need for that.
     
  4. fasteddy

    fasteddy I have C.L.A.P Global Moderator Generous Elf

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    My concern about this approach of having many individual controllers on the one DMX network is a high risk setup. I say this because the more connections, the more controllers and the more power supplies you have on a DMX network the higher the chance of having data issues which create flickering. I have seen 2 different people in the past week that have flickering issues when using this setup.

    See the issue with the tapping off the DMX data method is that instead of having the distance between the DMX data and the controller output right next to eachother on the board, instead you have a length of wire from the controller, the longer this cable the more reflecting signal that is experienced. It is this reflecting signal that can cause flickers. At very minimum i wou;d keep DMX supply to the controller from the main DMX data line as short as possible and I would install a 120 Ohm DMX signal terminating resistor at the end of the line.

    the Tiger DMX 48 is no longer available but you instead can get the AVD48 which basically replaced the Tiger48 but it is from David_AVD
     
  5. dmoore

    dmoore Senior Elf

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    I've used this setup without issue with nearly 100 controllers (3 channel) using all CAT5 connections. These connections, protected with CorrosionX have literally been laying in water. This is real-world experience, not a guess or opinion. I've seen more than a few customers with "flickering" and it has been a result of everything but a large quanity of controllers - mis-wiring, over current power supplies, conflicting software, shorting connections, bad wiring choices, etc.
    When people properly wire these controllers up, they work perfectly, even with dozens of them on a single line.
     
  6. fasteddy

    fasteddy I have C.L.A.P Global Moderator Generous Elf

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    But thats where the issue lie, the product is being aimed and sold to many LOR people who really have minimal experience and thus the higher increased chance of making a mistake or using bad wiring practices as this is not a plug and play system like LOR, you make your own plugs and connections.
    I know you have ran 100 + of these on the same network but that comment is only assuming all is equal which is never the case. And in reality you cant argue that the more controllers and power supplies you have on the same network the more complex it becomes and the harder it becomes to fault find because there are many more devices in the network that can fail.
     
  7. neilric99

    neilric99 Full Time Elf

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    The issue with these DMX controllers is that if it works, Great!, but if not then troubleshooting is not easy as it can be many things causing the issue.
    1. make sure you connections are good and solid and correct and you have not crossed the wires,
    2. you have a 120 Ohm terminator resistor at the end of the string of controllers to help load the circuit and prevent bounce back.
    3, having no DMX ground is not helping. Yes it sometimes works, but by luck rather than judgement.


    I did make a change to the holidaycoro design to use the brown pair (pins 7&8 ) as dmx ground, just means I have to inject power more often as only 2 pair are now carrying the current.
     
  8. dmoore

    dmoore Senior Elf

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    You are completely correct - I've told customers in certain cases, you'd be better off with an LOR solution that is completely plug-n-play. It's like this analogy - it's just like cooking your own food or going out to a restaurant to eat. If you cook your own food (DIY), you'll need to know what ingredients to purchase, in what amounts, how to mix those ingredients, how to cook them properly and how to serve them. Then, on top of that, you have to clean up after yourself (troubleshooting). More work - you bet, worth it? That depends on the users skill and time allowances.

    Some people don't mind the additional 2x or 3x additional costs and just want a plug-n-play solution and I think that is perfectly fine. Though that doesn't mean that one technical solution is invalid or less relevant - it's up to the user to determine which method or system best meets their budget and time schedule.

    While a fair number of my customers are coming from LOR, I spend a *LOT* of time supporting them and in the end, any customer that is willing to spend the time troubleshooting and learning the technology, I am willing to work with them to get a working solution and they do get their systems working. Do they make up wrong plugs and wiring connections? You bet they do, did you start off knowing exactly how all this works? No, you, like me both made mistakes, blew up things and in the case of pixels (back in 2010), we didn't even have someone to fall back on and ask questions of but that doesn't mean we didn't do it just because we were "LOR" people.

    Have faith that people can learn new things, even complicated ones like RS485 networks, DMX and E131 protocols, etc.
     
  9. fasteddy

    fasteddy I have C.L.A.P Global Moderator Generous Elf

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    David, you have no argument from me on those points, except that you, me and some others that started out knew very well that the path we were taking hadnt been walked before, so there was a lot of trial and error. But many of the people these days coming into RGB are not expecting or wanting to travel the same path of fault finding, they want it to just run.

    Unfortunatly we have seen many time where people look at the dollars and want to save a few dollars but struggle the whole way through because they have taken something on that is above their ability (including taking on pixels), even an LOR system is very daunting at first for many.

    But the system you sell is a valid system that has proven itself to work and is a great option for a distributed system where an element has its own self contained controller.
     

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