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Help Needed - DMX sequencing of tree and leaping arches

Discussion in 'The Development Lab' started by nulla28, Nov 15, 2016.

  1. nulla28

    nulla28 New Elf

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    Greetings LED gods.

    I need some help with the sequencing of my mini mega tree and leaping arches.

    Background:
    Two years ago I built 3 leaping arches using Big W LED lights (3 wire) consisting of 30 channels in total. These were connected to a 27 channel DMX controller linked to a 3 channel DMX controller. Controllers were powered using the power supply which came with the Big W lights, which were 30V output and had the plug and adaptor in the one unit. The sequence was designed and run using Vixen. Worked a charm, no issues even with splitting the 30 channels across the two controllers.

    Last year, I added to my display with a mini mega tree (probably about 3m high) again using Big W LED 3 wire which I already had on hand from a few years earlier. The tree consisted of 16 channels + 5 coro presents + 1 coro star = 22 channels total. I purchased a 30 channel DMX controller which I swapped over and used on my leaping arches to match the 30 channels needed there, and then connected my tree to the 27 channel controller which I linked in starting at channel 31. Again both controllers were powered using the 30V Big W power supplies and programmed using Vixen. Overall it worked, the tree which was linked second in the sequence worked perfectly, but a lot of the time I was getting some serious lag on the leaping arches which were first in the sequence.

    I was thinking there might be a problem with the new 30 channel controller but when I tested the leaping arches on the new controller without the tree, they seemed to work fine without lag. Adding the tree on, the tree works fine and the leaping arches start to lag.

    If anyone has any ideas or suggestions how to eliminate the lag, it would be appreciated. It really started to grind my gears last year. I have uploaded a vid to show an example of the lag. The movement of the leaping arches should be nice and smooth but from the 1:00 minute mark onwards the lag is extremely obvious:

    Christmas Light Display 2015 - YouTube

    Thanks for your help.
     
  2. i13

    i13 Senior Elf

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    Hmm...

    My first guess would be that you're using a USB dongle to control those. Doing so requires your computer's software to handle the timing so stuttering/lagging can happen. This is only a guess and the alternative is to use E1.31 with a DMX bridge. That's not a particularly cheap fix when I'm only guessing what the problem is. I had this happen but with much higher channel counts. Everything stuttered at once for me and not just one controller.

    What are your computer's specs? How much RAM and what processor?

    DMX can also misbehave but continue to partially work if you have a bad Cat5 cable somewhere along the line or if there's a bad RJ45 socket on one of your controllers. Have you added a termination resistor?

    How many lights in total are powered by each plugpack?

    I'd suggest inputting the signal at the other end of the DMX line and changing nothing else - see what happens.
     
  3. Charger

    Charger Apprentice Elf

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    Hi Nulla,


    I had a similar problem last year. See thread here. Very frustrating. Initially I thought it might have been a problem with Vixen, then I looked at the rest of my hardware. After lots of advice and kind assistance from other members, I was able to establish that my computer wasn't powerful enough to run Vixen directly to the lights through a USB dongle.


    I ended up running my show through a Raspberry Pi and using an E1.31 Bridge. A little bit more money, but my display ran every night without issue last year. Maybe see if you can get in touch with someone else locally who can run your controller and sequences through their pi and E1.31. If that works OK, it should confirm that your PC and USB dongle combo are the culprit. That being the case, I would highly recommend using this method.


    Good luck!
     
  4. OP
    OP
    nulla28

    nulla28 New Elf

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    Thanks for the responses.

    You are both right in your assumptions that I am using an AAH USB dongle.

    My computer processor is an Intel Core i7 2.30GHz with 8GB of RAM. The sequence runs with nothing else open, although I do have the preview running at the same time. Didn't know I could turn it off so I will look to kill the preview and see if it helps as a starting point.

    I might also have a shot at using a different Cat 5 cable, just in case.

    I am not using termination resistors. I am still very much a beginner when it comes to sequencing (as you can tell), are these required? If so, what do I use and how do I connect it?

    I have one power pack connected to the 30 ch DMX with 1,200 LEDs, and the other power pack connected to the 27 ch DMX with 600 LEDs. Brightness of LEDs appears normal.

    If I input the signal in reverse (into tree first and then out of tree into arches), should I swap the order in Vixen or just let the tree do the arches sequence and visa versa to test it?

    I'm in Bonnet Bay in Sydney, if anyone lives around the Sutherland Shire / Southern Sydney and has a Raspberry Pi / E1.31 bridge I could borrow to test the display, your help would be appreciated. I cannot easily bring my display to you, but can pick up and return to you in the one day and happy to leave some form of deposit.

    Cheers
     
  5. i13

    i13 Senior Elf

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    Yes - try disabling the preview.

    Termination is recommended but you can sometimes get away without it. It's simple enough that you may as well just do it. It's just a resistor between the DMX+ and DMX- at the far end of the DMX line. That's the Cat5 pins 1 and 2. See this wiki article. https://auschristmaslighting.com/wiki/DMX_Terminators

    Off the top of my head I think the plugpacks are only supposed to power up to 600 LEDs each. It's specified in the instructions that come with them. You can use multiple plugpacks to share the load even if the controller has only one input. Connect one plugpack to the controller as normal and join its negative output to that of another plugpack. DO NOT join their positives together - this can be electrically dangerous. Connect the positive output from the other plugpack directly to the light sets that you want it to power. Don't connect the positives for these light sets to the controller, only the negatives. It's the same as examples 2 and 3 in this wiki article except that your multiple supplies are the same voltage as each other. https://auschristmaslighting.com/wiki/Controller_Setups_and_Settings

    You will not need to change anything in Vixen if you try inputting the signal at the other end of the DMX line. All controllers see the same DMX signal and they will simply respond to the channels that you told them to.
     
  6. OP
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    nulla28

    nulla28 New Elf

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    Thanks for the tips.

    Just for my understanding when it comes to adding another power supply along the line. When I made the leaping arches, I was preparing myself to acquire a more elaborate power supply as you are correct that the power packs are generally suited to a max of 600 lights. However, given that all lights on the arch are usually not on at the same time, I gave it a shot with the existing power pack to see how it worked out. I figured if anything, the lights would just be dim. This has never been the case with it though.

    Could the power issue be a possible factor somehow in the lag, even though when it lags it doesn't lose power and the lights it gets 'stuck' on are still lit, and keeping in mind that when the arches operated in isolation two years ago, there were no issues?
     
  7. i13

    i13 Senior Elf

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    I'm really not sure what is causing this lag. Probably not the power as you're saying but keep in mind that if you halve the current passing through a LED, the drop in brightness appears much smaller than you'd expect. Still, I'd expect the LEDs to suffer before the controller because the controller cuts out below 12V and the LEDs would be well and truly dark by then. I don't know enough about the internal workings of the plugpack to say whether the voltage would just drop off or whether it would be unstable under too much load. If the lag happens when less than half of the lights are on then the power is probably not the issue. Wouldn't be hard to check that by just unplugging some of the lights.

    If you do find someone locally who has a bridge or Raspberry Pi then it might be worth asking if they have a power supply that you can try.

    Please post once you've tried plugging in the DMX signal at the other end of the line and you've tried termination. Termination is simple enough that you may as well try it and rule out the fact that it's missing as a possibility. It can also have the opposite effect and make the symptoms worse if there's something else wrong such as a bad Cat5 cable so it would be interesting to know.
     
  8. fasteddy

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

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    Are you using a DMX dongle connected to your USB port. If so then maybe check the port speed on your computer as it may be set to 9800 instead of 11500, if that's the case then that may cause lag

    Power shouldn't cause lag
     

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