Home Made DMX cables

[Brian]

the VDC digital (green series) single pair cable is a miniture cable ie the same as  a single cable out of a multicore and is not very good for repeated coiling or very robust for use on the road.

 

they do sell a cable specifically designed for DMX and the touring market but I dont think it is in the current catalog and is quite expensive

I can confirm that the VDC stuff is a little 'thin'. For serious use you want something like 'Tourplex Datasafe' but it is expensive at around £1/metre.

[peternewman]

I am sorry j_b but if we're being really pedantic then Cat 5 or 5e for that matter can be either stranded for making computer patch leads or solid for installation work, although you can use solid for making patch leads, however as mentioned elsewhere in this thread the solid is more liable to break if flexed about.

 

PN

 

Edit Grammar

[Matt]

if I am right, if you just wired pins 1 to 3 with cat5e, could you use passive hubs to distribute the signal over several lx bars as a permanent feature... or do you reckon the DMX voltage would bugger the hubs or the hubs would bugger up the signal (all they are doing is duplicating it into several ports, and amplifying it all to the incoming level)...

 

if it did work, the cheap £40 hubs from netgear and some cat5e cables and plugs etc..... could be a cheaper way of a permanent install... not that I am condoning it in any way, I say you should always do it the way it was meant to be done, with the proper stuff (if you have time/money)

[peternewman]

Hi

 

Just being a bit pedantic and clearing up a topic here. If the hub is passive then by the nature of the word passive it won't actually be doing anything apart from splitting the connection or are you getting confused between hubs and switches. From your description what you are thinking of is just a plain network hub as opposed to a switch. This as you have described simply applifies the signal and sends it out on multiple connections. You may need to look carefully at which pins to use as im not sure exactly how the hub would handle the connections. Also Cat 5 networking only uses 2 pairs and not all 4.

 

HTH

 

PN

[martinw]

if I am right, if you just wired pins 1 to 3 with cat5e, could you use passive hubs to distribute the signal over several lx bars as a permanent feature

 

No, ethernet hubs distribute ethernet only, not RS485 based signals like DMX, you need a DMX splitter here.

 

M

[Matt]

true, yeah was on about hubs then... not to sure at the moment, its a bit dark, a lamp has gone in my light :** laughs out loud **: , it does indeed use twisted pairs, ok, three pins and the outer casing just to make things easier, and to be pednatic :blink:

[ianl]

I Use Klotz cable. the OT206 digital cable is very very nice. You can actually coil it like mic cable, but it has the correct impedance.

 

http://www.klotz-ais.com/lshop,showrub,,e,...DMX.DMX,,,,.htm

 

Is the stuff.

 

John

I think I'm probably tired and can't see something right in front of me but where do you buy it from and how much is it

[Jivemaster]

Terralec do DMX cable at £56 inc vat+ carriage.

 

You must make cables up carefully getting 3 and 5 pin where you need along with all the polarity reversals as required.

[lampieman]

what is the point of wiring everything to 5pin, as most items are 3pin, and very rarely will the fixture have only 5pin, doesnt martin currently put both 3 and 5pin on there fixtures, where as at one point it was just 3pin

 

Gareth

[robloxley]

what is the point of wiring everything to 5pin, as most items are 3pin, and very rarely will the fixture have only 5pin

Well the spec for DMX says that extension cables shall use 5 pin XLR connectors. As for your kit having 3 or 5 pin connectors, it depends whether it's 'disco' or 'professional' kit. As for Martin, they're a law unto themselves as far as DMX connectors go!

[Stu]

Lets face it Martin aren't the only ones - Moving-lights.com shows that Coemar and High End both use 3pin XLR connections on their kit. Not to mention Robe, Pearl River etc

 

Stu

[P. Funk]

this goes against the specification.. but couldnt you just wire all your extensions 5 pin socket, 3 pin plug? then they would fit into both 5 and 3 pin devices either way wouldnt they?

[Stu]

You mean have a splitter on the end of each cable - in effect? If so, I doubt this would work as DMX split this way doesn't like it much!

 

Edit: Sorry didn't read your previous message properly... But if you wired 5 socket, 3 plug, surely you'd have to have extensions round the other way as well? Oh I dunno, but it seems like to me it's alot easier to have some jumpers in your kit to change 5-3, 3-5, 3-3 (phase reversal) etc

 

Stu

[TomLyall]

I think you ment one on one end, oen on the other, in which case I sorta see what you thinking, only needing one type of adaptor not two, however you would end up with a stock of non standard cables.

 

stu, your idea about splitting at either end could be quite good, I dont think it would matter about having a 20 cm or so bit of wire split at the end, it only matters when you actually split the signal and use it down a long chain...

[Blame Jono]

I've used mains flex instead of XLR before for coms with no probs over about 50m of cable so I cant see any reason for not doing the same with DMX.