dmx output pinout

[golights]

Anybody know what the pin out is for the 4 dmx universes on the rj45 when it is flashed for dmx.  Is it set up as a standard rj45? 

[rrowan]

The Etherdongle uses all 4 pairs

I believe

pins 1&2 universe 1
pins 3&4 universe 2
pins 5&6 universe 3
pins 7&8 universe 4

doesn't matter if firmware is pixelnet or dmx for universe pairing

Rick R.

[golights]

Thanks rrowan, do you know if the odd numbered pin is + or -.

[Steve Gase]

1 is +
2 is -

odds are +

[rrowan]

The full specs are in the wiki SmartString/Pixelnet library You are not allowed to view links. Register or Login

Page 6 of the Pixelnet Spec doc talks about it

Rick R.

[rm357]

I'm not sure those pairs are right.

Standard Ethernet pairs are 1-2, 3-6, 5-4, and 7-8.
Note pair three is reverse order - 1, 3, 5, & 7 are +.

This also appears to be the way the splitter is wired - checked with my ohmmeter.

RM

[JonB256]

I'm not sure those pairs are right.

Standard Ethernet pairs are 1-2, 3-6, 5-4, and 7-8.
Note pair three is reverse order - 1, 3, 5, & 7 are +.

This also appears to be the way the splitter is wired - checked with my ohmmeter.

RM

While I don't have one to check, I'm certain this is correct. If a high frequency signal was put on pins 3&4 or 5&6, it would fail because those are not actual twisted pairs for noise rejection.

[golights]

From reading the spec. it would seem that the wiring would be as a standard rj45 connector 1-2, 3-6,5-4,7-8  but the picture makes it seem as 1-2, 3-4,5-6,7-8.  I will get a meter out and check.     Thanks all

[rrowan]

I think the picture was drawn wrong. The reason for my bad info, its been a while since that came out and I forgot about that error.
It does use the standard layout and not 1-8

sorry

Rick R.

[chrisatpsu]

im just gonna let the active hub figure it out for me  : )

[mykroft]

I am looking at a combiner here, and port 1 is taking pins 1/2 to pins 1/2 of the output, port 2 looks like it is taking pins 1/2 of that port to pins 3/4 of the output etc

The RJ45 output I dont think is wired like standard ethernet output, as each twisted pair is a universe and not split up.....?
Myk

[chrisatpsu]

it's not that complicated...

pixelnet, and DMX are NOT Ethernet, they don't use ethernet cables, they don't use networking switches...

they use RJ45 connected cables... 
Ethernet requires each data pair to be on a physical pair to get the speed out of the cable...

the RJ45 connector...
1&2   uni1
3&4   uni2
5&6   uni3
7&8   uni4

you can make your cables any way you want as long at the ends match.
Ethernet is high speed and is limited to 328ft (~ a couple feet)  <---   has NOTHING to do with pixelnet / DMX  so don't try to place ethernet requirements onto something that isn't Ethernet

RJ mentioned that the pixelnet, and or DMX data can travel at least 1000ft. (pixelnet in this case is the connection dongle to hub, or hub to hub, not from hub to ssc)
EDIT: i made an exception for hub to ssc, b/c the distance would most like create a voltage drop, where at least a full string would not light up

old slow ethernet cables work with dmx / pixelnet, (you know the ones where the orange or green pair isn't split)

so, don't worry about the cable except that the pins match (don't use a crossover) and worry about the RJ45 connector physical pins odd,even

[n1ist]

Pixelnet was designed to use off-the-shelf cat-5 cables.  For historical reasons, the twisted pairs in cat5  (or cat6) are connected to pins 1 and 2, 3 and 6, 4 and 5, 7 and 8.

As Pixelnet (and DMX) both use RS485 as the underlying signalling scheme, you need to have both lines of a universe on one twisted pair to have the proper impedance and prevent interference from one to the other.

To avoid headaches and marginal performance, please use the correct pinout.  It's just like using mic cables for DMX - it will work until you really depend on it and then flake out mid-show...
/mike

[chrisatpsu]

Then you would need a 10.base t cable, which is not 568a or b.

Dmx and pixelnet are slow speeds in comparison to fast Ethernet. The twists in the cable are not as important.

And that's my point, if this stuff can run on xlr based dmx cables, then obviously we don't have to worry about high performance Ethernet cables.

Ethernet is designed the way it is so that we can get really fast speeds out of a piece of copper (or aluminum) which doesn't matter for this stuff.  There might be twists in a xlr based dmx cable, but it still wouldnt be anywhere near an Ethernet cable.   I can use cat 3 wire and make a good dmx cable. Because its slow speeds.