RGB Flickers

[Tracy West]

I am testing my RGB 5050 15m strips tonight and had some unpopular results.

When I run them directly from the dongle and not connected to other strips they are perfect.

When I run them from a 50 foot cat5 line connected to the dongle they flicker different colors almost strobe like even when they are programmed on one solid color.

Now.. I have each dmx controller powered seperately and not powered through the cat5 line, so it is not power that is the issue. They look great in dmx test mode. It is just when I have it playing the sequence that the colors are not staying consistent.

Any idea why that is doing this?

Is the data line too long or needs to be a better quality cat5?

I have a week to figure this out!

[edvas69]

If they are working in test mode then stat with the Cat 5 cable.

a couple of things to check

1: Ensure the CAT5 cable is a straight through cable and not a cross over cable

2: Ensure the cat 5 Plugs are in fully

3: If you are using solid core CAT5 cable then there may be abreak in the cable

4: the plug may not be making a good contact

5: Ensure the CAT5 cable is not near any mains AC cables as this can cause issues and induce interferance into the CAT5 data signal

Best thing to do is try a different CAT5 straight through cable and see if that works. If after that the issue still exists then it may be a data output issue from the computer or a software configuration issue..

Edited October 7, 2012 by edvas69

[Ron Boyd]

One thing I ran into was what everybody is calling a channel shift. I had to start my DMX universe on channel 2, instead of 1. Made all the difference in the world. Might try that.

[Tracy West]

If they are working in test mode then stat with the Cat 5 cable.

a couple of things to check

1: Ensure the CAT5 cable is a straight through cable and not a cross over cable

2: Ensure the cat 5 Plugs are in fully

3: If you are using solid core CAT5 cable then there may be abreak in the cable

4: the plug may not be making a good contact

5: Ensure the CAT5 cable is not near any mains AC cables as this can cause issues and induce interferance into the CAT5 data signal

Best thing to do is try a different CAT5 straight through cable and see if that works. If after that the issue still exists then it may be a data output issue from the computer or a software configuration issue..

Thank you.

I am feeling that it is a cat5 cable issue and not computer output issues because they work perfectly when the dongle is directly connected to just one of the dmx controllers and at short distance. It only flickers from the long distance. But you brought up a couple of things that I need to check before I change cat5 cable. You mentioned having the cat5 near the AC cable. I did. So I will place the AC away from the connecting cable.

[Tracy West]

One thing I ran into was what everybody is calling a channel shift. I had to start my DMX universe on channel 2, instead of 1. Made all the difference in the world. Might try that.

I did start my channels out at 2 so that was not the issue but thank you guys for all your input!

[Tracy West]

Still have that annoying flickering.

I am going to try a different CAT5 cable.

Frustrating.

[edvas69]

You may need to put in a 120 Ohm DMX terminator to stop reflecting signals being generated down the CAT5.

So on the output of the last controller you put a 120 Ohm terminating resitor across the output data signal.

Flickering issues can be real nasty to work out sometimes

[Tracy West]

You may need to put in a 120 Ohm DMX terminator to stop reflecting signals being generated down the CAT5.

So on the output of the last controller you put a 120 Ohm terminating resitor across the output data signal.

Flickering issues can be real nasty to work out sometimes

So you just connect the 120 Ohm Terminating Resitor to the last CAT5 connection that does not have anything attached to it?

And where do I get these resistors?

Thank you for all your help.

[edvas69]

A 120 ohm resistor should be able to be obtained from any electronics store. The 120 Ohm resistor would then connect to the DMX output. you could easily make a terminating plug by just cutting a CAT 5 cable to near the plug and then connecting the 120 ohm resistor between pins 1 (data +) and pin 2 (data -)

I did forget to ask before, what dongle are you using for your DMX output. If you are using the LOR dongle with DMX devices then have you added an adaptor to change the LOR pins to DMX pins. as LOR and DMX use different pin numbers.

[Tracy West]

A 120 ohm resistor should be able to be obtained from any electronics store. The 120 Ohm resistor would then connect to the DMX output. you could easily make a terminating plug by just cutting a CAT 5 cable to near the plug and then connecting the 120 ohm resistor between pins 1 (data +) and pin 2 (data -)

I did forget to ask before, what dongle are you using for your DMX output. If you are using the LOR dongle with DMX devices then have you added an adaptor to change the LOR pins to DMX pins. as LOR and DMX use different pin numbers.

I am using the Holiday Coro dongle with the same dmx controllers attaching them to the rgb lights.

What if the last dmx controller just had an input and not an output. Would that resolve that issue as well?

I have two dmx universes and the other one is using the 3 pin in and outputs and it is my understanding I will need a resistor connected to the last unit as well.

[edvas69]

ARH Ok now i know what you are using.

The issue with these controllers is that they dont follow the DMX standard very well as instead of having an In and output they just have an input.

A normal and standard DMX device will have a DMX in and a DMX out and the signal just daisy chains from controller to controller. Using these cheap controller there is no DMX out so instead you have to 'tap' from the DMX signal to go to the next one. You must ensure that the distance between the DMX data cable and the data input cable of the controller is as short as possible as if you have too long of a cable that T's off the data cable then this is a strong possability of creating your issues. Try disconnecting all the cheapo 3 channel controllers from the network (unless thats all you have) and seeing if the results are the same with the remaining controllers. Then add one at a time and test, remember make sure that the DMX input cable is not long at all from where it T's off the main DMX data line as this can cause issues.

Can you explain in a lot more detail on your controller layout and how you have the controllers connected to eachother

[CLD Kevin]

Eddy always has the best answers….this is why I always read his replies!

If your using the 3ch dmx modules and RJ45 splitter, then the distance cant be very long as Eddy stated. These were not designed for this. However, those 3ch dmx modules do have an In and Out…just the Out doesn’t come with wires connected to them. You would have to open every one and solder wires. I personally never tried using the Out of these…I used the RJ45 splitter method, but mine were 5 ft apart from each other. Bring the dmx signal to the devices and then T off the main with very short runs.

Also you’re using a open dmx dongle which uses your pc for the timing. How many channels are you using and what specs is your PC? Not saying this is your problem but may be better to use a dongle with a processor built in…like the Enttec Pro.

For my terminating end, I used this

http://www.ebay.com/itm/DMX-512-3-Pin-Lighting-Terminator-Short-Version-/200791112670?pt=US_Cables_Snakes_Interconnects&hash=item2ec0153bde

My last dmx device had an XLR connector so this was the best choice for me. If your last point is Cat5 connection, then you can purchase a 120 Ohm resistor from Radio Shack and solder as Eddy stated.

[edvas69]

Thanks Kevin for the kind words and heads up on those controllers, I have one here as a sample but i never went about pulling it apart, that is good to know that they actually have an output. So to save a few cents on an output cable they instead leave it off.

Edited October 8, 2012 by edvas69

[Tracy West]

Eddy always has the best answers….this is why I always read his replies!

If your using the 3ch dmx modules and RJ45 splitter, then the distance cant be very long as Eddy stated. These were not designed for this. However, those 3ch dmx modules do have an In and Out…just the Out doesn’t come with wires connected to them. You would have to open every one and solder wires. I personally never tried using the Out of these…I used the RJ45 splitter method, but mine were 5 ft apart from each other. Bring the dmx signal to the devices and then T off the main with very short runs.

Also you’re using a open dmx dongle which uses your pc for the timing. How many channels are you using and what specs is your PC? Not saying this is your problem but may be better to use a dongle with a processor built in…like the Enttec Pro.

For my terminating end, I used this

http://www.ebay.com/...=item2ec0153bde

My last dmx device had an XLR connector so this was the best choice for me. If your last point is Cat5 connection, then you can purchase a 120 Ohm resistor from Radio Shack and solder as Eddy stated.

Thank both of you for all your help.

This transition to dmx has been a learning curve and this was my first dyi project too. You don't get all the ends and outs when you go dyi, you just get bits and pieces and this is what comes from it. Confusion!

My connections are less than 5 foot apart on the roof, except for the 30 feet or so of CAT5 running to them from the computer. I went with the cheaper dmx controls and not the CCR's for one main reason... Didn't have the funding this year to make big of a leap but I wanted the RGB experience.

They all work well indivudually so I think it is the open dmx end. I will give thie resistor a go and hope that is it. If not... a lot of flickering mess I have this year.

[edvas69]

When you say your connections are 5 foot apart do you mean the data supply cable to the controller is 5 foot away from the DMX data line. Im trying to get an understanding of how you have physically connected the controllers from the usb dongle to the first controller and so on and an idea of how long the data cable is from the join you made to supply the dmx data to the controller.

What sounds like is happening is the signal is being reflected down the line. This can happen when using these controllers and having the dmx cable to far away from the actual controller. DMX is designed to be daisy chained, the method used with the controllers is a parrallel method where you tap off the DMX signal to each controller. The issue here is that if the DMX signal cable length that is tapped from the main DMX cable to the controller is too long then you will create data refections with the signal which then causes havoc to everything that is connected to that network, So when using these controller it is best to make sure that the length of the DMX input cable is as short as possible so as to minimise this data refection issue that you may be creating by using longer lengths.

The Terminator may help with this but if the signal reflection is large enough then the terminator will still not stop the flickering and your only cause of action would be to ensure that the controller input signal cable is as short as possible from the main DMX signal.

The other question I have to ask is how have you powered up and connected these different controllers. Have you used just the one power supply or have you used more than one and if so have you tied the DC ground together between these seperate power supplies as ground loops can also cause this issue.

Flickering can be a nasty issue to sort out and sometimes be caused by a combination of issues and this is one of the things you may have to be prepared to deal with when doing a DIY setup, theres a reason its called DIY and a reason why its cheap. DIY allows many combinations of setups which sometimes may not work very well if not correctly applied. Dealing with LOR you get a setup that has been designed to work with eachother, it comes at a cost but it has warranty, backup and a lot less potential hassle.

[plasmadrive]

If I am not mistaken the DMX input cables are very short to those controllers.. something like a few inches.. If that is the case you should not have any issue tapping them at the end of those short cables. Just use the terminator at the last one in line and make sure you daisy chain them correctly.

As for it being noise.. DMX is a RS485 protocol that is fairly noise immune. If you use good cables you should not have any issues next to AC cords in your application. It can be an issue with very long runs and high current waveforms, but only if you have less then stellar cables. Use the terminator resistor at the last one in line. Cat 5 cable is ok for DMX.

Per Wikipedia: DMX512 is a bus network no more than 1,200 metres (3,900 ft) long, with not more than 32 devices on a single bus. If more than 32 devices need to communicate, the network can be expanded across parallel buses using DMX splitters. Network wiring consists of a shielded twisted pair, with a characteristic impedance of 120 Ohms, with a termination resistor at the end of the cable furthest from the controller to absorb signal reflections. DMX-512 has two twisted pair data paths, although specification currently only defines the use of one of the twisted pairs. The second pair is undefined, but required by the electrical specification.

The E1.11 (DMX512 2004) electrical specification addresses the connection of DMX512 signal common to Earth ground. Specifically, the standard recommends that transmitter ports (DMX512 controller OUT port) have a low impedance connection between signal common and ground; such ports are referred to as grounded. It is further recommended that receivers have a high impedance connection between signal common and ground; such ports are referred to as isolated.

[Tracy West]

The way I have the RGB strips hooked up is I have them running through the Holiday Coro dongle connected to CAT5 cable. This cable is approximately 30 feet long that goes up the side of the house to the roof and connects to the first dmx controller and power supply. (I made each dmx controller have its own power supply and not powering them all through the CAT5 as some have done). I daisy chain the next controller and it is approximately two feet away. Then I daisy another with approximately 25 feet of CAT5 to the other roof line and repeat the process with two more controllers that are hooked up the exact same way as the first two. The last one does have an open end on the dmx control that needs to be closed.

My question is if I created a dmx control unit with only one input (without an output to daisy) would that close the dmx signal or would I still need the resistor at the end to close the dmx signal?

I am going to have this same setup on the ground as well but I have not gotten that far yet because of halt in buildup due to this issue.

Starting to stress now due to so close to buildup and production.

The woes of being a first time DYI virgin!

[christmas chris]

Don't stress Tracy, at least your DMX light come on! I can't get them on with the Coro dongle or the USB485. Me being new to LOR doesn't help either, but at least my AC controllers work! Worst case scenario, I will have 28 ugly black and white plastic lumiaries bordering my yard....

[Ron Boyd]

Don't stress Tracy, at least your DMX light come on! I can't get them on with the Coro dongle or the USB485. Me being new to LOR doesn't help either, but at least my AC controllers work! Worst case scenario, I will have 28 ugly black and white plastic lumiaries bordering my yard....

Same here, all I can get out of them is the test sequence. I'm using a different DMX controller from Seasonal entertainment and it works. I just can't get the blasted little white box to work.

[christmas chris]

FINALLY!!!!!! I did it, my lights work, I now know the problem, and I will not have ugly black and white plastic boxes around my yard, well at least they will light up pretty colors at night....

Any ideas though why my coro dongle/programmer is not setting the addresses in my controllers? I went through step by step installing the driver for it, then plugging in each controller one at a time,and assigning addresses, but just for fun I tried reassigning a channel in SE to channels 1-3 and it worked...????