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Terminate lighting ethernet?

Discussion in 'Lighting and Electrics' started by Sayen, Jan 27, 2009.

  1. Sayen

    Sayen Active Member

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    I'm still playing catchup with our lighting network, and a visiting LD told me I should have terminators in each of the open ethernet ports around the theater. Before I make a case for this to the powers that be, can I get a quick confirmation of this? We're using PathPort protocols, if that makes any difference.
     
  2. derekleffew

    derekleffew Resident Curmudgeon Senior Team Premium Member

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    Hopefully said LD will never be in your building again, but if he is, I'd ask him to go wash a pile of dusty gelatine sheets.:twisted: (Assuming your wiring is CAT-5 and not Thick-Net or Thin-Net, i.e. obsolete.)
     
  3. TimMiller

    TimMiller Well-Known Member

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    You NEVER TERMINATE EITHERNET. Now the old thin-net, back when computer networks were made by using bnc cable and T's, then you had to terminate using a 50ohm resistor at the end of your data chain. But todays eithernet you do not terminate. You would probably freak out the data switch if you tried to.
     
  4. gafftaper

    gafftaper Senior Team Senior Team Fight Leukemia

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    You get box of 3 pin XLR terminators and a box of 5 pin XLR terminators. That's all you ever need.
     
  5. Chris15

    Chris15 CBMod CB Mods Premium Member

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    The single case where you should be terminating a Cat 5 port is where you are running straight DMX over it, use of Cat 5 is kosher under the latest revision of the standard from memory, but surely one would need to be somewhat of a fool to use RJ45s for DMX purely for the number of people who would mix it up...

    Oh and you COULD terminate ethernet, it is a balanced system after all... Would it be wise, probably not, would it do more harm than good, probably.

    Just what did this guy expect you to terminate the ports with anyway?
     
  6. Sayen

    Sayen Active Member

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    Ah - he probably thought it was straight DMX over CAT-5.

    Thanks all, appreciate the quick answers. It seemed odd, so I thought I'd ask.
     
  7. Footer

    Footer Senior Team Senior Team Premium Member

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    Because ethernet is a star topology, there is no possible way to terminate. If there is nothing on the line, the port simply shuts down. Now, if you have an opto running strait up DMX to jacks around the space, a case could be made to terminate empty ports, albeit a weak one.
     
  8. JD

    JD Well-Known Member

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    I've never seen it done. Technically, it does contain an outgoing data stream from the router, so somewhere there may be a book that recommends termination. Still, I have never done it and I have run hundreds of miles of CAT5 in IT work. However, I do recommend that lines that are not in use for extended periods of time be disconnected from the router. No point in providing a way for a stray voltage or secondary EMP from a lightning hit to find its way into the router.

    DMX is a backbone system, so you have many devices on the same data line. The last device should be terminated. The modern xx-base T Ethernet is a "star topology" system, where each line has a dedicated T/R on either end. Kind of like a private line as compared to a party line. (oops! Dated myself!)
     
  9. Esoteric

    Esoteric Well-Known Member

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    I have never terminated a DMX run (and never had any problems with it), I also don't "lop back" scrollers. I know I am a rebel.

    Mike

    and yes, I know you should terminate, blah blah blah. If I had problems I go back and add a terminator, but so far in 10 years I have had this problem exactly 3 times. Oh! There is one unit I terminate (HES Color Commands).
     
  10. ScottH

    ScottH Member

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    Think about it: an ethernet switch operates the same as an opto right? Would you ever terminate each port on an opto that you're not using? As its been said if its DMX over CAT-5 the story changes. If you are using CAT-5 at all (DMX or ethernet) you wont even be able to find a terminator. Thin-net is different because it is a thru-line/daisy chain topography. Check the pathport documentation and see if terminators are even mentioned. I doubt it.

    I second the washing of gel task for that guy. Tell him to do his own job and not yours...politely of course.
     
  11. renegadeblack

    renegadeblack Active Member

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    I'm familiar with CAT5 in the networking sense, the only thing that I could imagine doing is sticking a little rubber stopper in there for termination :) As was said, absolutely no need.
     
  12. MNicolai

    MNicolai Well-Known Member Fight Leukemia

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    All of our unused ports on our Unison system came with rubber covers on them, but that's hardly a termination. It's just to keep the dust out.
     
  13. renegadeblack

    renegadeblack Active Member

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    That was my point.
     
  14. tomed101

    tomed101 Active Member

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    I happen to have a RJ-45 terminator sitting on my desk in front of me as I post. It came out of a Color Kinetiks PDS-70 power supply for LED MR-16 fixtures which receive DMX through CAT-5. It is definitely not a standard part as this one is a standard RJ-45 connector with a 120 ohm resister inside and is filled with silicone.
     
  15. gafftaper

    gafftaper Senior Team Senior Team Fight Leukemia

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    I vote you go put a little square of black gafftape over the ports not in use and tell the guy they are terminated.
     
  16. Footer

    Footer Senior Team Senior Team Premium Member

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    Hate to be that guy, but not really. An opto takes in a signal, and reproduces it out all ports, no matter what the data is. A ethernet HUB takes in a signal, and reproduces the same signal out all ports, no matter what the data is or where it should be going to. An ethernet SWITCH takes in data from one port, looks at the datas destination, referances a table on where that data should go, and sends it out the right port. The only piece of equiptment that recives the data is the equiptment it was enteded for. This makes for a much more effecient way to move things around, but it can cause latency in the system.

    Add to that I have read my fair share of Cisco books, and have never heard of termination beyond thinnet and thicknet.

    Now, those token ring DMX networks.... thats another story.
     
  17. ScottH

    ScottH Member

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    Footer: you are absolutely correct. I was mistaken when i threw the word switch in there, I should have said hub.

    Tomed101: that terminator you have is not an ethernet terminator but a DMX terminator with a different connector. Just be sure it doesnt find its way into an ethernet system. Im not sure what effect it would have. Maybe footer can enlighten us on this one ;)
     
  18. DaveySimps

    DaveySimps CBMod CB Mods Premium Member

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    We have a PathPort system and have NEVER terminated anything but DMX lines (scrollers, moving lights, etc.). I agree with the thought that the LD should go sort screws in the shop as opposed to giving lighting "advice"

    ~Dave
     
  19. Sayen

    Sayen Active Member

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    In fairness, he was a very nice guy, and everything else he said was on par. :grin:

    Thank you all for the responses, I learn more every time I log in.
     
  20. tcahall

    tcahall Member

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    Ethernet is a very different network from DMX512. DO NOT TERMINATE IT. It is a very intelligent network. If the port is empty, Ethernet will turn it off and not transmit information to it. If something is plugged in, it will attempt to handshake with the remote device and establish the physical address of the device (the MAC Address). This unique to every physical device and is encoded into the chip at the factory. If you plug in some type of a terminating plug, you run a good chance of having the hub identify you as a screamer. (a device that has lost handshake and is "screaming" data at the network) if you have a modern, good hub, it will turn you off. If you have an older device, it may shut down the entire network.

    DO NOT PLUG ANYTHING BUT A VALID ETHERNET DEVICE INTO AN ETHERNET PORT. Plugging in a passive (like a patch cord) will do nothing. It is common practice in offices to patch every ethernet plug under every desk into a port on a hub, even though no one is at that desk. When someone sits down and plugs in a laptop, the network comes to life.

    Tim.
     

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