We talked about DMX last week and one of the biggest problems discussed was the limitation to only 512 channels. DMX was not created with the foresight that some lights might be channel hogs and the need for more channels was born, this is where Architecture for Control Networks (ACN) comes in. The first release was ANSI Standard E1.17-2006 and was revised again in 2010. Most likely the main reason we still use DMX today is because of its modularity making it adaptable to whatever needs that might arise in the future. The idea of modularity was not forgotten for ACN which is divided into multiple different protocols. The first protocol is the Common Architecture which specifies a format of multiple PDUs or protocol data units part of which must be the Root Layer Protocol. These PDUs are used to connect the multiple higher-level protocols. Next is the Session Data Transport (SDT) which us used when broadcasting using multicast over UDP. This provides reliable multicast support so that packets have assurance that they’ll find their target. The other great feature of SDT is the ability to customize the tradeoff of latency, level of reliability, and processing power. Allowing for better scalability on large or small number of connections. The Device Management Protocol (DMP) allows any device to be represented as a set of addressable value to represent its desired state. While what we have talked about so far has operated over UDP and multicast, the DMP has been operated over TCP to provide reliability. The Device Description Language (DDL) allows programs to understand the description of the interface and capabilities of any device to be networked with. The DDL is XML based and can be downloaded from each device itself or over the internet. Most controllers will contain a cache of different devices commonly encountered. The last is Interoperability profiles (EPIs) which act as an internal service discover in a system mainly helping with multicast over UDP. The first major extension of this protocol is E1.31 also known as sACN or Streaming ACN. ACN has been implemented in multiple different pieces of hardware and software but nowhere is it more prominently implemented than by Electronic Theatre Controls (ETC) who based their own line of control infrastructure on it.

An implementation of E1.31 can be found on a shared repository from Nicholas and I.

Here is the link if you want to take a look!

https://github.com/nicntj/sACN-E1.31

Sources:

http://powers.media.mit.edu/wiki/upload/E1-17ACN2006DDL.pdf

http://www.rdmprotocol.org/files/What_Comes_After_Streaming_DMX_over_ACN_%20%284%29.pdf