Hardware DMX

[claytor1999]

OK... so I came across a You Tube video of a guy controlling his LOR lights with a hardware DMX controller (looks like an audio mixing board with sliders). That seemed like a good idea for controlling my Wirekat MR16s on the top of my bookshelf. My wife isn't about to turn on the living room computer, pull up vixen, etc... to get a little mood light going.

So instead of asking first if this would work I made the assumption it would work and bought a cheap board. The board arrived yesterday so... after making an XLR to RJ-45 cord with my poor soldering skills I plugged it in and... flicker. I've made sure all my connections are correct, the Lynx MR16 controller is terminated, etc... but still a lot of flicker.

Before I pack this thing up and return it does anyone have an ideas... DMX cord length, grounding, etc...? I like having an option for turning on mood lighting quick but not sure I'd use it that often (unless I start putting on plays or concerts in my living room - not sure that's going to happen at my age). I need to learn to leave well enough alone.

Thanks,
Robb

[RJ]

Not controlled just flickering or is it controllable and just flickers ?

If the first he may use the reversed DMX connections. Some stuff has the DMX wires switched from the standard.

RJ

[claytor1999]

Hi RJ - it's controllable, just flickers. I have 3 MR16s hooked up to 3 channels and they flicker in tandem (at least appears that way). The flickering is random but constant. I've tried changing the wires on the pins but get the same thing.

Thanks,
Robb

[rrowan]

Hi Robb

First I am assuming that you have the Lynx MR-16 start address set to 1. Figure the board is starting there.

With a volt meter:
RS485 - Pin #5 = ground - Pin #8 = 5v, Pin #1 = Output

Pin 5 & 8 should be around 5 volts

Move the slider to full on and take some readings at the rs-485
Take a reading on Pins 5 and 1

Move the slider to off
Take a reading on Pins 5 and 1 (should be slightly less then above)

If above is good then test the output on the Lynx MR-16

Move the slider around and put your meter on the channel one outputs and see if the voltage changes. Should go from zero to about 12 volts (assuming your power supply to Lynx MR-16 is 12 volts)

Rick R.

[dr. jones]

are you giving the mr16 board dc current or ac? led's will flicker on ac current

[claytor1999]

Hi Rick,

Not sure I'm following you on the pin assignments. On the DMX hardware the pin assignments are:

Pin 1 = Ground
Pin 2 = - Data Signal
Pin 3 = + Data Signal

On the RJ45 side (Lynx MR16) I'm assuming:

Pin 1 = + Data Signal
Pin 2 = - Data Signal

So maybe the problem is my cable is configured wrong?

Checking the output of the channel on the Lynx MR16 gave some interesting results:

With the software setup (Vixen --> Enttec Pro --> MR16) the voltage was stable once I stopped moving the slider (maybe a little jump once but stable)

With the hardware setup (Hardware Board --> MR16) the voltage kept on dancing around once I stopped moving the fader.

Let me know if I have the pinout configuration completely messed up - might be the answer.

Thanks!
Robb

[claytor1999]

Hi Dr. Jones,

The hardware runs off of a wall wart - DC 9V - 12V 500mA. Since the software setup (Vixen --> Enttec Pro --> MR16) works fine I assume that my power supply running the MR16 is OK.

Thanks,
Robb

[rrowan]

Robb

See the wiki for the pin out of the cable. You are not allowed to view links. Register or Login (should give you the correct info)

I was talking about the a chip on the MR-16 controller ( 8 pin chip in a socket next to the crystal)

Rick R.

[smartcontrols]

Just a long shot for you to try, but I had a similar situation with my lighting board. It worked fine if I did not of my controller terminated but would not work if the terminating resister was on. I know it sounds backwards. Just something that worked for me.

Jeff

[RJ]

If the units uses swapped DMX lines this is waht it will do. Try hooking up the lines reverse to the unit.

RJ

[claytor1999]

Thanks for all the input gentleman!

Jeff - you hit a 3-pointer from half court. Without the MR16 terminated the lights are flicker free.

RJ - by swapped DMX lines do you mean reverse polarity? I'd like to keep the terminator on so if I switch back and forth from Vixen to the lighting board I don't forget to put back on the terminator. Would an RJ-45 terminator for the DMX Out work instead of taking off the terminator pins? Maybe I need to just keep my mouth shut and enjoy the flicker free LED light coming off my MR16 board minus a terminator. 

Rick - good weather right around the corner on the Atlantic seaboard!  Thanks for the input - glad I got a chance to use my multimeter for something.

Have a good day guys!
Robb

[Murl]

Hi Robb,

Have you tried swapping the + and - like RJ said?  That's a pretty common issue with RS-485.

If so, then just out of curiosity, I'd shut everything down and then check the resistance between the data+ and data- signals coming from the hardware board.  Since it's working for you without the terminating resistor on the MR16 side, then there's a good chance that it's either not properly terminated on the transmitting end, or there's a cable issue.

If it's properly terminated, you should read around 120 ohms between the signal wires.  (If you can manage to check it with the cables connected and both ends terminated, it should read around 60 ohms since the resistors are in parallel).

One other question just out of curiosity...  You wouldn't happen to be using a really short DMX cable, would you?  Generally speaking, for RS-485 they recommend at least a 3m cable to minimize reflections.  I've used shorter cables without issue, but it's something to throw out there since its working better for you without the resistor.

Thanks for sharing with us!

-Murl

[claytor1999]

Hi Murl,

I'll take some readings tonight and see what I get. I have swapped the + and - with no luck.

The cord appears to be around 10ft long so maybe I need to try something a little longer. I've got a longer one I can try - I'll let you know the results.

Thanks for the input Murl - appreciated.

Robb

[Murl]

Robb,

If your cable is around 10ft, that should be plenty long enough.  I was thinking you might possibly have this set up on a bench with a really short adapter cable for testing. 

It wouldn't hurt to try a different one, though, since a bad cable can cause issues like your seeing.

-Murl

[rrowan]

Hi Robb

Just curious, what controller did you get?

Thanks

Rick R.