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    mario brustia
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sacn universe and multicast port

Good morning everyone, I'm now getting into the ACN world and I need clarification.

In the SACN protocol there is the term UNIVERSE which indicates, from what I understand, the universe to which the 512 DMX channels that are sent belong.

Now I have set the multicast address to 239.255.0.1 and transmit the universe number 1 without problems.However, I also sent other universes to the same address, there too without problems.

I checked with SACN View where both unviverses and channels were activated or not ,and everything is fine.

On the ETC website, on the SACN MULTICAST CALCULATOR page I read that if I want to transmit universe 1, I have to use the address x.x.0.1 while if I want to transmit, for example universe 5, I have to use the address x.x.0.5.

In my tests I transmitted on the same address, both universes different from the calculated one (example universe 4 on address 230.255.0.1) and even more universes (example uni1,2,3,4 on address 230.255.0.1) without problems.

Using sacnview I read all configurations correctly.

My question is: why do I have to use universe>address correspondence? Am I obligated to use it? can I transmit multiple universes on the same address? does the term UNIVERSE... have two different meanings?

thanks to anyone who can clarify the concept for me.

Mario

Parents

  • i think the standard asks for the multicast address representing the universe. but yes, in the packet itself the universe is specified as well. i'm sure it has something to do with multicast and receivers subscribing to a specific universe.

  • in reply to ueliriegg

    I do not understand. Using sacnview, in tx mode vs another sacnviwe istance (on other pc) I can change universe without change ip address and...i see all data in the original universe (packet in ascn string, not in ip address).

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  • in reply to ueliriegg

    I do not understand. Using sacnview, in tx mode vs another sacnviwe istance (on other pc) I can change universe without change ip address and...i see all data in the original universe (packet in ascn string, not in ip address).

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  • in reply to mario brustia

    Using sACN View 2.2.0-beta1. The Tx looks ok.

  • in reply to sstaub

    mmm....

    yes..I had seen it, but at this point could it be that the protocol provides only one IP address for a single universe uni1>ip1 uni2>ip2 and so on?I have not found any ref in 1.31 doc.
    However, I tried to send 4 universes on the same IP and the viewer decoded them without problems. I don't have real sacn peripherals available, I'm developing my own light control software and I'm trying to implement the protocol but i've this doubt: one ip for multi universe, ore one ip for one universe?
  • in reply to mario brustia

    Did you send via Unicast instead of Multicast? This is absolutely different to Multicast. You need to test in a real environment. Also beware of using IGMP in your software. 

  • in reply to sstaub

    Yes,multicast...but I think I must test in a real environment.however the doc is not clear. ..thank's for the support!

    Mario

  • in reply to sstaub

    Wow...no! My only docs is the official ansi 1.31! Thank's for that!!!

  • in reply to mario brustia

    This is in the standard document, chapter 9.1: Association of Multicast Addresses and Universe
    "Addressing and partitioning of multicast traffic is achieved by setting the least significant two bytes of the multicast IP address [..] to the desired universe number."

    And there's the table in 9.3.1 Allocation of IPv4 Multicast Addresses, that's also quite clear.

  • in reply to ueliriegg

    Opposs...thank's again.i've not understand the doc.my English is so bad.thank you for the patience!! Ciao

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