dmx and lor on the same cable?

[Ebuechner]

I have a 75ft run from my computer out to my 1st controller .  can I use 2 usb 485 to use 2 separate wire pairs on the cat 5 cable to run dmx and lor simultaneously without cross talk between them? or do I need to run 2 cat 5 cables? lor blue pair dmx orange pair on one cable is what I want to do so I don't have to have a mess running out the window

[Max-Paul]

You can try. But  I would think that there might very well be crosstalk problems. What is going to help keep down the crosstalk is you need to keep the signal level below 0db.

[plasmadrive]

Actually you can run multiple RS485 networks o a Cat5e

[Ebuechner]

I don't want to re event the wheel . I just don't want to commit  to this setup if it has no hope of working. One wire would be nice. Has someone else done this successfully with lor and dmx? Not to second guess you plasmadrive but I want to be sure.

[Max-Paul]

I  am going to have to defer to Plasma. If I had asked the question and Plasma came back and said it would work, I would go out and do it. Plasma knows his shite. I just know somethings from book learnings I have picked up over the years in different training I have taken. I know one thing, in many cases if the signal is over 0db crosstalk is a very good possibility.

[plasmadrive]

Thanks Max. 

 

Ebuechner, from Wikipedia:  http://en.wikipedia.org/wiki/DMX512

RJ-45 pinout

1. Data 1+
2. Data 1-
3. Data 2+
4. Not Assigned
5. Not Assigned
6. Data 2-
7. Signal Common (0 V) for Data 1
8. Signal Common (0 V) for Data 2

 

The 8P8C modular connector pinout matches the conductor pairing scheme used by Category 5 (Cat5) twisted pair patch cables. The avoidance of pins 4 and 5 helps to prevent equipment damage, if the cabling is accidentally plugged into a single-line public switched telephone network phone jack.

 

From Pathway:   http://www.pathwayconnect.com/content/view/91/26/

 

The following table is shows the ANSI E1.27-2 standard DMX pinout when

using Category 5 (or higher) wire and an RJ45 connector:

 

Wire Color

and #

Function

Equivalent

XLR Pin #

 1

White/Orange

 Data + (pair 1 true)   3

2

Orange

 Data - (pair 1 complement)  2

3

White/Green

 Optional Data + (pair 2) 5

6

Green

 Optional Data - (pair 2) 4

4

Blue

 Unassigned -

5

White/Blue

 Unassigned -

7

White/Brown

 Common   1

8

Brown

 Common  1

[Ebuechner]

thank you. The last thing I need is to find out it doesn't work after everything is set up

[beeiilll]

I have about 80 feet to my first and tried to do exactly what you wanted to do and the crosstalk was nasty! Too many hiccups and strange errors randomly.

It was just way too easy to just run a second Cat cable for the Dmx and eliminate any troubles right from the start!

[plasmadrive]

I have about 80 feet to my first and tried to do exactly what you wanted to do and the crosstalk was nasty! Too many hiccups and strange errors randomly. It was just way too easy to just run a second Cat cable for the Dmx and eliminate any troubles right from the start!

I would bet you had a wiring issue.. Running two universes on a single Cat5 has been done many times but many people. There is even a standard for it.. it works when done correctly.  But.. with that said, for that short of a distance it is a pretty easy run for a 2nd cable...

[Ebuechner]

my question is what is signal common ( 0 V ) for data.  is that the ground ?  I'm running though a window and the less wires getting pinched the better . Hear in Wisconsin we can get to -20  and I want the window tight without damaging the seal

[plasmadrive]

RS485 is a differential signal.  That means that is has a D+ and a D- which are 180 deg out of phase for the data and must be in a single twisted pair, but you still need a common.  When trying to do this, some people mistakenly connect the wires incorrectly. They try to double up on the Data wires or they run both D+ down the same twisted pair.. and same with the D-.. they try to run them down the same pair. That won't work well.

 

Follow the standard wiring and I think you will be fine.  It works for me as well.

 

Oh yeah.. signal common is 0V... that is ground sometimes..  0V is often called ground by many..

[Ebuechner]

I know to put the data + - on the same pair to cancel out noise as you said 180 out of phase. dmx orange pair lor blue pair 0v green pair for my setup leaving pin 3 open on the ctb16pcg3 side. dmx should pass through pins 1 and 2 .  can I get a low level audio signal in there on the brown pair pins 7 and 8 or is that pushing it to far

 

I just tested pins 1 and 2 I guess that they don't pass through the ctb16pcg3   but that can be fixed

Edited August 29, 2014 by Ebuechner

[plasmadrive]

You can use one of those RJ45 splitters.. and put a very short cable to your controller.. I had to do that last year to two of my controllers because the pass thru jack was iffy..

 

As for the audio ..... it should work just fine.. I would think..

[Ebuechner]

Thanks. This is helpful.  Happy lighting

[JonB256]

... but you still need a common. ..

No common (third wire) is needed for RS485.

[plasmadrive]

No common (third wire) is needed for RS485.

Actually that is both true and false.   Depends on situation.  In a lab perhaps not.. in the field, Usually! 

 

http://www.chipkin.com/rs485-cables-why-you-need-3-wires-for-2-two-wire-rs485/

 

More from BB 

Signal ground, don't forget it. While a differential signal does not require a signal ground to communicate, the ground wire serves an important purpose. Over a distance of hundreds or thousands of feet there can be very significant differences in the voltage level of "ground." RS-485 networks can typically maintain correct data with a difference of -7 to +12 Volts. If the grounds differ more than that amount, data will be lost and often the port itself will be damaged. The function of the signal ground wire is to tie the signal ground of each of the nodes to one common ground. However, if the differences in signal grounds is too great, further attention is necessary. Optical isolation is the cure for this problem

[Max-Paul]

No common (third wire) is needed for RS485.

In most cases your correct. But if you read the white papers about the RS-485 protocol you are mistaken. The ground wire provides the reference point for the two differential signals. And as you might know, The wiring make up of the LOR RJ-45 jacks have the +,-,9VDC, and ground wires. Along with 2 pairs not used but passed through each of the controllers. So, yes, there is a ground wire common to all of the LOR controllers.

[Jack Stevens]

DANGER!  There is potential damage in some of the above answers!  (not all) Plus the simple risk of things just not working.

 

As far as the cable goes, the answer is yes.  You can run 4 different RS-485 signals down that 4 twisted pair conductor cable.  The twists are different for each pair, reducing the chance of crosstalk between the signals, using "common mode rejection" methods.

 

HOWVER, and here's the "it won't work" or worse yet "blow up a controller" part.

 

The "blow up a controller part" - LOR has its sigles on pins 4 and 5, and puts +9 on pin 3 and the ground is on pin 6.  This is to run this is to provide a voltage supply for things such as the iDMX-1000 and the MP3 controllers.  That could potentially damage your other controllers......not likely, but could.  It could also get shorted out and stop your LOR controllers from working.  CTB16PC controllers gen 1 and 2 will pass through all other signals.  I've heard that gen 3 doesn't do that (can't prove that, don"t have one) and some of the other LOR products don't, either.

 

On the other side, DMX generally uses pins 1 and 2 for RS-485 signalling, secondary set of signals on pins 3 and 6 (either disabling the volage supply from LOR or getting blown out by it, or both)   Renard in DMX mode uses pins 4 and 5, and shorts 1-3 and 6-8 to ground, not allowing pass-through of any other signals.  Renard in DMX mode also does a channel number adjustment, pulling off the first 8-16-24 channesl (depending on number of channels in the controoler) and adjusting the rest of the DMX string down in channel numbers.

 

Other DMX controllers may also ground out the non-used pins, or use them for other things.  The RJ SSR-4 with the DMX option uses the other wires for triac control.

 

So yes, you can use a single cable for moultiple protocols, as long as you keep the wiring specifications for each controller you use in mind and make the appropriate wiring adapters.

[plasmadrive]

DANGER!  There is potential damage in some of the above answers!  (not all) Plus the simple risk of things just not working.

 

As far as the cable goes, the answer is yes.  You can run 4 different RS-485 signals down that 4 twisted pair conductor cable.  The twists are different for each pair, reducing the chance of crosstalk between the signals, using "common mode rejection" methods.

 

HOWVER, and here's the "it won't work" or worse yet "blow up a controller" part.

 

The "blow up a controller part" - LOR has its sigles on pins 4 and 5, and puts +9 on pin 3 and the ground is on pin 6.  This is to run this is to provide a voltage supply for things such as the iDMX-1000 and the MP3 controllers.  That could potentially damage your other controllers......not likely, but could.  It could also get shorted out and stop your LOR controllers from working.  CTB16PC controllers gen 1 and 2 will pass through all other signals.  I've heard that gen 3 doesn't do that (can't prove that, don"t have one) and some of the other LOR products don't, either.

 

On the other side, DMX generally uses pins 1 and 2 for RS-485 signalling, secondary set of signals on pins 3 and 6 (either disabling the volage supply from LOR or getting blown out by it, or both)   Renard in DMX mode uses pins 4 and 5, and shorts 1-3 and 6-8 to ground, not allowing pass-through of any other signals.  Renard in DMX mode also does a channel number adjustment, pulling off the first 8-16-24 channesl (depending on number of channels in the controoler) and adjusting the rest of the DMX string down in channel numbers.

 

Other DMX controllers may also ground out the non-used pins, or use them for other things.  The RJ SSR-4 with the DMX option uses the other wires for triac control.

 

So yes, you can use a single cable for moultiple protocols, as long as you keep the wiring specifications for each controller you use in mind and make the appropriate wiring adapters.

This is a good catch.  I forgot the OP wanted to run DMX AND a LOR network.  I was just posting about the ability to run multiple networks.  The bottom line is that you should be able to run those two networks if you use the correct wire pairs and the correct pin outs. 

[Steven]

I drive speakers over the brown pair and the orange pair, using transformers to change 8Ω to higher impedance, and have never had any crosstalk problems. There is no reason why multiple RS485 networks shouldn't work.

 

The +9V on pin 3 shouldn't damage anything if it accidentally shorts to a DMX or LOR controller, because RS485 can handle voltages from -7V to +25V.

 

If the +9V shorts to ground, it will probably cause excess current to flow through the voltage regulator in the LOR controller(s), which may cause them to overheat and shutdown, but it probably won't destroy them. But even if it does, it won't make any difference unless you're using a ELL or a motion sensor or an SC485 that need power.

 

On the other hand, if you accidentally plug the LOR network into an Ethernet controller (or switch, or LAN port), then the Ethernet transformer will probably be destroyed. Don't do that.