DMX over cat5e

ewsclass66

Member
Joined
Aug 21, 2020
Location
United Kingdom
We have 2 runs of cat5e to each lighting bar, we attempted to turn one of the runs into a DMX line by soldering the ends of the cable to a 5 pin XLR connector however we have been experiencing issues in regards to what we believe interference. Fixtures occasionally flicker and the flickering is removed when connecting to the fixtures directly using DMX from our ArtNet node. We followed the pinout re using cat5e as dmx. Would running an additional STP cat5e for dmx use solve our issue?
 

ewsclass66

Member
Joined
Aug 21, 2020
Location
United Kingdom
Check for proper termination. UTP may not work in places where STP will.
We soldered the correct wires to the correct pins, made sure to double check that. Shorter runs work fine just seems to be the long ones. The cables do run parallel to dimming and mains cable in places however i thought twisted pair was supposed to mitigate this?
 

microstar

Well-Known Member
Joined
Jan 19, 2014
Location
Lawton, OK
We soldered the correct wires to the correct pins, made sure to double check that. Shorter runs work fine just seems to be the long ones. The cables do run parallel to dimming and mains cable in places however i thought twisted pair was supposed to mitigate this?
Maybe post a photo showing attachment of the Cat5 to the XLR?
 

FMEng

Well-Known Member
Fight Leukemia
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Mar 31, 2008
Location
Tacoma, WA
We soldered the correct wires to the correct pins, made sure to double check that. Shorter runs work fine just seems to be the long ones. The cables do run parallel to dimming and mains cable in places however i thought twisted pair was supposed to mitigate this?
Sorry, I meant does the last device on the run have a termination resistor plugged in?

Here's a nice reference with the proper connector pinout.
https://support.etcconnect.com/ETC/FAQ/DMX_Over_Cat5
 

ewsclass66

Member
Joined
Aug 21, 2020
Location
United Kingdom
Sorry, I meant does the last device on the run have a termination resistor plugged in?

Here's a nice reference with the proper connector pinout.
https://support.etcconnect.com/ETC/FAQ/DMX_Over_Cat5
The terminator actually caused more problems, all fixtures in the chain would flash violently when the terminator is plugged in. Will be difficult to get a photo as the theatre is in use for socially distanced presentations for a while. We made sure to make a nice solder joint and heat shrink around each pin when done.
Followed this guide https://www.google.com/url?sa=t&sou...WMAJ6BAgEEAI&usg=AOvVaw3mjUxw7csrQxvrwfPpa37K
 

DrewE

Well-Known Member
Joined
Mar 18, 2019
Location
Vermont
It sounds as though one of the two data lines might have a poor or broken connection; adding a terminator will tend to cause a high-resistance connection to have less signal strength. Have you verified the electrical integrity of your connections with an ohmmeter?
 

ewsclass66

Member
Joined
Aug 21, 2020
Location
United Kingdom
It sounds as though one of the two data lines might have a poor or broken connection; adding a terminator will tend to cause a high-resistance connection to have less signal strength. Have you verified the electrical integrity of your connections with an ohmmeter?
No I haven't, thanks for the suggestion will give it a try, what kind of resistance should I be looking for?
 

DrewE

Well-Known Member
Joined
Mar 18, 2019
Location
Vermont
With no devices or terminators connected to the cable at either end, there should be no connection (infinite resistance, or very nearly so) between the wires, and low resistance along each individual wire. Often it's convenient to test the latter by shorting together the two conductors at one end and measuring the resistance of the resulting loop from the other end. The expected resistance in this case, doing a round trip through two conductors, would be in the neighborhood of ten ohms per hundred feet of cable.
 

ewsclass66

Member
Joined
Aug 21, 2020
Location
United Kingdom
With no devices or terminators connected to the cable at either end, there should be no connection (infinite resistance, or very nearly so) between the wires, and low resistance along each individual wire. Often it's convenient to test the latter by shorting together the two conductors at one end and measuring the resistance of the resulting loop from the other end. The expected resistance in this case, doing a round trip through two conductors, would be in the neighborhood of ten ohms per hundred feet of cable.
Great thank you will give it a try when I'm next in
 

RonHebbard

Well-Known Member
Premium Member
Joined
Jun 12, 2004
Location
Waterdown, ON, CA
Having been taught how to solder at EMI (I thought I already knew how to solder - boy was I wrong) I can knock up an RJ45 to XLR quite quickly by chopping a patch lead in half and attaching an XLR-5, but I've seen some who also think they can solder make a real horlicks of it.
This Canadian worked for a Canadian company contracted to build five, fully populated, 44 RU racks for an installation on the Strip in the heart of Las Vegas.
Tussauds in England paid my boss to supply, pre-wire, ship, and supervise the on site installation; two of us were there for a few days longer than four months to install, program and test "On other people's money" as the phrase goes.

The two of us were put up in separate rooms in an all suites hotel with a fridge in every room, our 24/7 buffet breakfast included, and a row of taxis out front waiting to ferry us down town once or twice daily "On other people's Money.

A 20 hour per day brew pub was immediately next to our front door where we purchased our own dinners EVERY evening seven days per week for a few days more than four months.

Never having seen the installation skills of our local IBEW crew, we packed more than fifty each of Neutrik Male and Female XLR-three's, fours, fives and sixes. We only needed to install ONE XLR 7 pin Male on site; we packed one + one spare.

You don't want to view the artful remnants of the first connector one of our best local crew "created" soldering free hand atop a personnelle lift using an iron better suited for sweating together 10' lengths of 1970's galvanized metal eaves trough.

To the gentleman's credit, he definitely gave it his best for approximately two hours. When finished The connector's pins were neither parallel nor of a similar length. It got "interesting" when I threw a 7 contact Female up to him to try mating it,
The gentleman could terminate Twistlocks from 2 contacts to 5 / 15 amps to 30 but Neutrik 7's were not in his skill set.

During his coffee break he decided this was an impossible task and agreed to my riding a scissor lift, with him along to observe, and prove before his own eyes that terminating 6 or 7 conductors of foil shielded 22 gauge stranded could actually be accomplished sans creating a mound of smoldering plastic with seven tiny pins stuck in at jaunty angles.

Live and learn and preferably on "Other people's money".
Toodleoo!
Ron Hebbard
 

DBL

Member
Joined
Jul 28, 2020
Location
Plano, TX
I've used CAT5 for DMX extensively but it can be a problem since the cable is usually solid copper. I've seen what appear to be good solder joints and screw terminal connections turn out to be intermittent nightmares. Best to use a properly installed RJ45 connector and an RJ45 to 5 pin XLR adapter. Also, when connecting directly to a fixed connection (i.e. wall box or output of a splitter) in a permanent install be sure to use an insulation displacement type connector, not a screw or pressure pad type.
 

Rossclan

Member
Joined
May 22, 2020
Location
Fort Ann, NY
This Canadian worked for a Canadian company contracted to build five, fully populated, 44 RU racks for an installation on the Strip in the heart of Las Vegas.
Tussauds in England paid my boss to supply, pre-wire, ship, and supervise the on site installation; two of us were there for a few days longer than four months to install, program and test "On other people's money" as the phrase goes.

The two of us were put up in separate rooms in an all suites hotel with a fridge in every room, our 24/7 buffet breakfast included, and a row of taxis out front waiting to ferry us down town once or twice daily "On other people's Money.

A 20 hour per day brew pub was immediately next to our front door where we purchased our own dinners EVERY evening seven days per week for a few days more than four months.

Never having seen the installation skills of our local IBEW crew, we packed more than fifty each of Neutrik Male and Female XLR-three's, fours, fives and sixes. We only needed to install ONE XLR 7 pin Male on site; we packed one + one spare.

You don't want to view the artful remnants of the first connector one of our best local crew "created" soldering free hand atop a personnelle lift using an iron better suited for sweating together 10' lengths of 1970's galvanized metal eaves trough.

To the gentleman's credit, he definitely gave it his best for approximately two hours. When finished The connector's pins were neither parallel nor of a similar length. It got "interesting" when I threw a 7 contact Female up to him to try mating it,
The gentleman could terminate Twistlocks from 2 contacts to 5 / 15 amps to 30 but Neutrik 7's were not in his skill set.

During his coffee break he decided this was an impossible task and agreed to my riding a scissor lift, with him along to observe, and prove before his own eyes that terminating 6 or 7 conductors of foil shielded 22 gauge stranded could actually be accomplished sans creating a mound of smoldering plastic with seven tiny pins stuck in at jaunty angles.

Live and learn and preferably on "Other people's money".
Toodleoo!
Ron Hebbard
Yeah. That would have been me except I would have given up long before his 2 hours. Me and soldering irons have a hate-hate relationship. Scenery, rigging, pnuematics, high voltage--that I can do. Low voltage is not my friend. :cool:
 

ETCFIELDENG

Lin Wheeler ETC, Inc.
Joined
Oct 25, 2007
Location
Atlanta
To transition from Cat5e to stranded wire you should be using something that allows an IDC / Punch-down connection for the Cat5e and possibly a terminal strip for the stranded wire. You just can't / shouldn't solder UTP. Search online and you will find several items that do this in one format or another. Most are RJ45 to terminal strip. https://www.google.com/search?rlz=1...TYuMpgBAKABAaoBB2d3cy13aXrAAQE&sclient=psy-ab

This is something we do a lot of using in-house parts but I'm sure you can find something online.
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