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Author Topic: 7-Pin DMX -- help!  (Read 3894 times)

Dianne Zahnle

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7-Pin DMX -- help!
« on: March 10, 2009, 05:12:56 PM »

Hi all --
I make cable for a couple of install companies around town, mostly audio, and a friend of a friend's cousin needs a 7 pin DMX. Trying to find out what he's trying to hook up is proving to be complicated as I dont have the guys direct info and the go betweens dont get what I'm asking.
I know how to make 3 and 5 pin DMX but I have no idea how to do this 7 pin, I don't want to spend a fortune getting 7 conductor cable especially if data is only on 3 pins. So does anyone know the pinout? The only info I've been able to glean from the Internet (dubiously) is that roscoe fog machines use all 7 pins and the Zero88 control (frog/leapfrog desks??  Confused  I'm only familiar with audio boards so I have no idea if these are really crappy or really good)
Also, I have a few leads on getting 7 conductor cable but if anyone here knows where to get some, any info would be appreciated!
Thank you!!
PS Do you think I can get away using shielded cat5?
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John Birchman, CTS

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Re: 7-Pin DMX -- help!
« Reply #1 on: March 10, 2009, 05:21:43 PM »

There are some 7-pin XLR Connectors, but I don't think I have ever heard of anyone using them for DMX.

You can use Cat-5 for DMX:

http://www.barbizon.com/newsletters/06fall/linked/dmx_graph. html

Let us know if you find out anything else on this 7-pin DMX and what uses it.

John

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John Birchman, CTS
Freelance AV and Stage Technician
JRB Technical
Lake Buena Vista, FL

Phil LaDue

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Re: 7-Pin DMX -- help!
« Reply #2 on: March 10, 2009, 09:22:29 PM »

Wow, that's weird.
7 pins!!!!!

Adam Whetham

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Re: 7-Pin DMX -- help!
« Reply #3 on: March 11, 2009, 12:02:01 AM »

I've heard of 6 pin for some ETC lighting boards, but never 7. I know I've seen some. What equipment is he trying to use?
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James Feenstra

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Re: 7-Pin DMX -- help!
« Reply #4 on: March 11, 2009, 01:18:14 AM »

http://www.controlbooth.com/forums/lighting/6260-7-pin-dmx.h tml

that link can probably provide you with an answer or two
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James Feenstra
Lighting, Audio and Special Effects Design

Dianne Zahnle

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Re: 7-Pin DMX -- help!
« Reply #5 on: March 11, 2009, 03:45:38 AM »

Thanks for the link!

So after spending far too much time reading every single forum, data sheet and white paper on dmx in general, calling every lighting guy I know, I now know way more than I ever wanted to about DMX (no knowledge or learning is ever wasted tho! who knows when I'll need it) I have discovered that NO ONE uses 7 pin and the responses have all been similar to Phil's of "that's crazy!!" which, as helpful as it is, are leading me to this solution pending any info from the client:
Heavy Duty cat 5 since I have no idea if this is permanent or temp so I don't want wimpy stuff, its rated at 100 ohms impedance so it should be fine, it's available in stranded so hopefully it'll reduce the risk of breakage if it is going to be handled either once by gorillas installing it or multiple setups and teardowns, shrink over each contact in a futile attempt to eliminate cross talk at the termination...
But then the question of shielding arises -- a few articles said that unshielded could be used in standard dmx if its run through conduit, pretty sure thats not going to be case because it's sort of hard to pull a terminated cable...  So if I use 7 of the 8 conductors on the pins and the 8th to the tab (which I dont really want to do) would that be good enough? Or would it cause issues since there is no shield to drain to and the wire I'd be using as a ground would be insulated? I don't know that on the gear one of the pins isn't already ground so then I'd have a loop  Confused am I overthinking this?
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John Birchman, CTS

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Re: 7-Pin DMX -- help!
« Reply #6 on: March 11, 2009, 10:45:16 AM »

According to ESTA test results "Data obtained from all three of these test sessions confirms that, in most respects, UTP and STP
Category 5 cable can be expected to perform at least as well as EIA-485 rated data cable for DMX512
applications. Detailed supporting test documentation is provided in the subsequent parts of this report."

http://www.esta.org/tsp/working_groups/CP/DMXoverCat5.htm

If you are using Cat5 cable, connect as follows:

Pin 1 Ground (connect to both White/Brown and Brown)
Pin 2 Data - (Connect to Orange)
Pin 3 Data + (Connect to White/Orange)

(if you are using 5 pin - connect as follows, otherwise do not connect these colors to anything)
Pin 4 Dat2 - (connect to Green)
Pin 5 Dat2 + (Connect to White/Green)

Blue and White/Blue are not connected to anything.
If the cable is shielded do NOT connect to Pin 1 (some say do not connect to anything).

Hope this helps.

John

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John Birchman, CTS
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JRB Technical
Lake Buena Vista, FL

Dianne Zahnle

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Re: 7-Pin DMX -- help!
« Reply #7 on: March 11, 2009, 03:58:11 PM »

Thanks for help John, I read that paper last night too -- I understand how to make everything work on Cat5 for 3/5  pin dmx -- aka the normal, sane people uses -- but this 7 pin thing no ones heard of is turning into a pain in the rear... I'm just going to make it, charge the client and cross my fingers. I'll fix it for minimal cost if it doesn't work but I'm spending way too much time on this already!  Razz I'll let you know if I learn something new and exciting about 7-pin
Cheers!
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Duane Massey

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Re: 7-Pin DMX -- help!
« Reply #8 on: March 11, 2009, 09:53:07 PM »

I could be far off-base here, but I'm going to take a wild guess that this is not a DMX application, and it wouldn't be a shock to find out that they want a DIN connector, not an XLR. There have been several pcs of equipment from years ago that used 5-8 pin DIN connectors, but a 7-pin is a bit odd (unless they are counting the grd pin). The fact that you are having difficulty getting all the info has got to be troubling. Good luck!
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Duane Massey
Houston, Texas, USA

Milt Hathaway

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Re: 7-Pin DMX -- help!
« Reply #9 on: March 12, 2009, 05:57:12 AM »

Duane Massey wrote on Wed, 11 March 2009 20:53

I could be far off-base here, but I'm going to take a wild guess that this is not a DMX application, and it wouldn't be a shock to find out that they want a DIN connector, not an XLR. There have been several pcs of equipment from years ago that used 5-8 pin DIN connectors, but a 7-pin is a bit odd (unless they are counting the grd pin). The fact that you are having difficulty getting all the info has got to be troubling. Good luck!


I've had the same feeling, primarily because 7 pins = 6 analog channels + ground (return). 6 channels/connector was very common on smaller systems (although it was usually on an 8 channel Cinch-Jones connector.)
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