DMX Jacks

[Anonymous067]

Okay guys. I don't mean to call you guys wrong, but here's what I know.

Right now, all the DMX A jacks are probably (let's assume for right now) daisy chained together. The dimmer rack is plugged into one DMX A plug, but DMX A plugs still exist in at least four other places in the venue.

Those other jacks (or jills...whatever) aren't terminated. So I can't see how it can get worse by plugging another device into another jack.

But, just in case, the dimmer rack is closer to the stage than the booth where the board is, so my first backup will be running from the dimmer rack to the 1st electric (hiding cables is no longer my concern anymore...).

Anyways...

btw-anybody know is MAC250 Entours jacks are auto termed (the thru connector that is)?

 

[derekleffew]

...btw-anybody know is MAC250 Entours jacks are auto termed (the thru connector that is)?

The only known moving light with auto-termination is the ETC Revolution. See this and subsequent posts.

And no worries about calling anyone wrong. All are equal here. On the Internet, no one knows you're a dog.

 

[kicknargel]

Someone will probably have more technical info, but. . .

There is a difference between daisy chaining devices using thru ports and parallel wiring (y-splitting) dmx runs. The device has electronics that pass along the signal properly. Anyone disagree?

That said, if there's an optical splitter in your system, you should be able to plug in multiple devices. If not, and they're parallel wired, you should be able to plug in one device (or chain) to only one port at a time. If A is running to your dimmers, use B to control your devices, and make one chain coming from any convenient port. I doubt having terminators in every unused plug is necessary.

On your issue with having some light not work until rebooting--I've had that same problem with the Innovator. It always seems to be related to patching. Things will show that they're patched on the screen, but won't be controllable. The only console I've ever had to reboot. Lame.

Nick Kargel
www.youwantwhatproductions.com

 

[Gmont]

BLah067

I did not watch closely to the post times but I would recommend to go to your theatre with a note pad a do some serious scotting. It sounds like you have only half the picture and it is not going to be possible for to give you much help until you have more info. Start and the beginning. (do remember in the things below to put it back as you found it until you are ready to make changes. I am sure you would but just wanted to say it.)

Ask for a set of drawings. It is surprising how many times they are on a shelf that is not thought about until some asks. If you can get it that will give you a map to start with and them go and verify it.

Next start at your console and follow its cable to the wall. Found out exactly what is pluged where.

Once you have done that go to your rack and see what is there. Most install racks do not have a jack around them. They are hard wire straight into the brain. Now here is the trick most install racks also have a termination switch in the brain. (this would explain why a daisy chained system has not given you grief) Also how many dimmers do you have, and how many racks (more importantly brains).

Also look around the rack and see if you find an opto splitter.

Next go to a least two of the jacks wall plates and take them off the wall and look at the wire soldered to the back. Is there two wires or one? (make sure to go to two that way you are sure the one you checked is not the end of the chain) If there are two wires then it is daisy chained if there is only one then you can make the assumption that there is an opto splitter and GO LOOK FOR IT.

Don't be afraid to this, it is something we all do. To truly know whats going on you need to know what is really happening don't just assume.

As far as some of the other stuff to restate some of what was said before.
My source for this info is Cadena in his Automated Handbook

DMX should never be split without a opto splitter, the result is data reflection and data corruption. (you may do and it may work but it is taking a chance)

DMX should not have more then 32 loads (devices) per branch or runs longer than 1640ft. If you exceed this you should use a data distribution amp (opto splitter).

Each branch of DMX should be terminated. This makes it look like your cable is infinitely long and eliminates data reflection. Plug the terminator into the last device on each branch.

You should also only use DMX (100-120 ohm) data cable and not mic cable to connect your equipment (I am sure many can tell you that they used mic cable with no problem including me, but be aware that it is not the best option)

Before you go pulling cable all over your facility it sounds like someone made an effort to make your life easier, so find out if they did.
If you find that they are daisy chained for ease sake I would say not to use them. Make the home run to your console to ensure less problems.
Also as I am sure you are aware from doing sound work, there are things that can be done and work but that does not mean they will work reliably. Example: our theatre forgot to terminate a DMX branch and it worked through rehearsals and tech until opening night. On opening night our fog machine took off and filled the theatre before they could get it turned off. So it is a roll of the dice if you don't follow the standard

Hope this answers some of your questions,
G

 

[pathway]

We've encountered this same daisy-chained DMX setup many times and people have come up with a few novel ways to try making things "right". But most don't do squat and just hope for the best, if they even realize in the first place why their system is so flaky. We get a lot of tech support calls because of this.

Opto-splitters are by far the best way to create a "legal" DMX distribution system, but this option is precluded when a single 1/2" conduit links all the port boxes. Some insert 1-in, 1-out repeaters at each port box location, but that's a little expensive and not really necessary unless more than 32 devices are connected on the same run.

One solution I've seen that's effective, if a little awkward, is to have a female XLR on the front plate of the box and a 12" pigtail cable with male XLR hanging out the bottom. The female is wired from the console or the previous box, and the male cable carries on to the next box. The male is left plugged into the female if DMX isn't needed at that location, passing the signal straight through. If you want to connect a scroller PS or a few movers there, you simply run a couple of DMX extensions from your gear back to the box to cut the unit(s) into the daisy-chain. Presto - no broken rules and everything works fine. We recently started making a 1-gang wall plate insert with male & female XLRs and a pushbutton "pass-thru" switch that does the job without the pigtail. You still need a terminator at the end of the line, though, and it should be left plugged into the last box (or device connected there) which of course would only have a female on it.

 

[Tex]

On your issue with having some light not work until rebooting--I've had that same problem with the Innovator. It always seems to be related to patching. Things will show that they're patched on the screen, but won't be controllable. The only console I've ever had to reboot. Lame.

Nick Kargel
www.youwantwhatproductions.com

I've had the same problem with patching and having to reboot. Try putting a mover into a submaster; it never works the same way twice!
To the OP: I'm willing to bet that your B universe will work just fine for your movers. My theatre was built just before intels became popular. I have no DMX outs anywhere. I converted two mic inputs (one backstage and one FOH) to use for DMX. This does not adhere to the DMX standard and many will tell you that it's unreliable. This may well be true, but the only problems I had during the run of the show were with the Innovator itself. Over a longer run with more performances, I may have encountered more DMX problems and YMMV but my experience was good.