DMX, Ethernet and PoE

Sparkie

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Feb 5, 2007
Our new console should be arriving in the next week or so (Strand Palette) and it's now time to purchase some additional bits. I'm installing a wireless access point for RFU and also laptop usage at the production desk. The clever thing to do now whilst I have some funds is build something in for the future - DMX over ethernet.

I am looking at getting a 16 port switch to handle networking but have a question about ethernet to DMX nodes. Obviously I should be getting a switch that supports PoE and cannot find all the information I need to make that decision. I've looked at the specs for Pathport and Strand but have come up empty on what may be a crucial factor in determining which switch to buy - what are the power requirements for these nodes? Not much good forking out for a switch that supplies 4w per port and the node needs 6w.

I'd also be interested in hearing your comments about combinations that work (or more importantly, don 't) for you.
 

Footer

Senior Team
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From what I have been told, strand does not want you to use off the shelf POE switches. What they suggest is to go with 3com power injectors and then patch into a standard 24 port switch. There are some issues with how some power injectors work with the SN110 nodes. I have personally bought an injector that does not work with the nodes that is compliant to the PoE standard. Call your local strand rep or the strand mothership and ask what injectors they install. I doubt it will be a powered switch. I will take a look in our rack at some point and see what is in there.
 

jmabray

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Feb 9, 2007
Location
Dallas, Texas
This is because the Strand nodes don't meet the standard, not the power injector or POE switch.

As for POE switches, the ones that I have dealt with have all had an overall power rating (i.e. can supply 90 watts over the switch) not a per port power rating. So unless you are going to have a poe switch that is fully loaded (i.e. something on all 24 ports) It's not really that big of a worry.

I would talk to strand though. Since you have made the decision to use their equipment, the should be willing to tell you what devices you need to make it work right.

Jeff
 

farmerjo1111

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Jun 23, 2005
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Arena, WI
ETC recommends and uses the LINKSYS/SRW224P for any Ethernet that requires POE. I would defiantly contact Strand and see what they say, they may have tested a couple of variety of switches or POE injectors. If your looking for POE injectors another company to look at is called Powerdsine.

Dustin Strobush
ETC Systems Group
 

koncept

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Mar 6, 2005
Location
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i would still go with a poe switch as it may be useful for things like your access point and other nodes down the road, (if money is an issue leave it out...) but then i thought of my high school and the terminal strip splices used to inject power to the nodes. I didn't like what it looked like and thoght there were better ways but thats what we got....
 

SteveB

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Mar 20, 2004
Location
Brooklyn, NY
ETC recommends and uses the LINKSYS/SRW224P for any Ethernet that requires POE. /QUOTE]
I purchased this same unit for my Net2 system a year ago. ETC used to recommend a Cisco PoE, so the Linksys (same company) recommendation is new. In any case it's a rock solid unit and has never caused me issues.
Steve B.
As a follow on, I kept my non PoE switch for all those devices not needing PoE, such as the Emphasis/Express system, all the Sensor CEM+ racks, Unison and the laptop when used as a remote console. The PoE switch lives right underneath the regular switch and simply connects specified lighting e-net connections. Not all devices like PoE, and I have certain e-net taps throughout the theater specifically labeled as "Lighting Network - Powered Port", but can re-patch to a non powered port as needed.

SB
 

Footer

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As a follow on, I kept my non PoE switch for all those devices not needing PoE, such as the Emphasis/Express system, all the Sensor CEM+ racks, Unison and the laptop when used as a remote console. The PoE switch lives right underneath the regular switch and simply connects specified lighting e-net connections. Not all devices like PoE, and I have certain e-net taps throughout the theater specifically labeled as "Lighting Network - Powered Port", but can re-patch to a non powered port as needed.
SB
PoE "as standard" should not affect anything that does not take PoE that is on the line. It should be auto sensing, and if no resistance is felt across the pins, nothing goes out.
 

koncept

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you beat me to it footer.... To add to that there are both non standard and standard switches/injectors out there. from the sounds of this discussion you need a non-standard injector that just puts power out there. if you were to use a standard injector it would wait till it detects the device and then turn it on.

We have poe switches in the office I work in, and as footer said they wait till they detect a poe device. my laptop is a great example (too bad i cannot charge it w/ that poe) it does not draw any power but if I plug an ap into the same port it would.
 

SteveB

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Mar 20, 2004
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Brooklyn, NY
PoE "as standard" should not affect anything that does not take PoE that is on the line. It should be auto sensing, and if no resistance is felt across the pins, nothing goes out.
I was following the advice of ETC tech support concerning non PoE required devices (I believe their 4 port portable node was one they advised not sending power to) and in any event had more devices and taps on the network then the 7 ports on the PoE switch supported, thus needed to use both switches.

SB
 

jmabray

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Feb 9, 2007
Location
Dallas, Texas
The 4 port node requires more power than the 2 port node does ( or less or something about it is different - I don't remember- that job was a haze...) There is a device that Linksys makes that can put the right amount of power on the line for a four port node to get power. It consists of 2 parts. Part 1 puts power on the line and part 2 takes it off and puts it into the power plug of the 4 port node.... I had to use it on a job recently, but I honestly don't remember the difference right now....
 

SteveB

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Mar 20, 2004
Location
Brooklyn, NY

Balo

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Apr 24, 2007
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Based in Portland, OR - Touring
After much testing with many options, I found this:

Manufacture Diodes, IGBTs, LED Driver, Small Signal & Analog, RF Power, SCR, WLAN Power Amplifier, Backlight Inverter, CCFL Inverter, Power Modules, RF Transistors, Power Over Ethernet, PoE, PoE IC

I purchased a used PowerDsine 6024 on eBay and it has never let me down. It automatically senses what's a PoE device and what's not and therefore you can plug anything into the network and it will work properly without fear that it will damage it.

Best of luck!
-Chris
 

Malabaristo

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Jul 11, 2008
Location
Wisconsin
A word of caution with used products from PowerDsine: they were making POE injectors before the 802.3af standard was ratified so some of their older products will not work correctly with devices that follow the standard. Ideally all the products you would be using should meet the 802.3af standard to insure interoperability.
 

Sony

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Aug 13, 2008
Location
Massachusetts
I don't know if it is compatible with Stand Nodes but at NNHS we have ETCNet3 nodes and we use two Dell PowerConnect 3524P PoE Switches to power everything. They are very nice professional grade rackmounted units.
 

Lightingguy32

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May 2, 2006
Location
New York
You could look at the Cisco Catalyst 3500PWR series switches. They are fully managed and if I remember right 50% of the ports are POE while the other half are standard.