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Old October 8th, 2008   #6
Join Date: Feb 2006
Posts: 430
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No worries! I set this forum up as a place to cover all these types of questions.

I'm going to preface the answers with that these are my own personal thoughts and comments and shouldn't be taken as gospel or as the view of others in the RDM group.

Why has ACN taken so long to take off?
ACN is a very complicated and ambitious protocol. It took more than 10 years to develop. It is not the type of protocol that is easily implemented in existing products and is more likely going to require it to be part of a ground up design. ACN was released shortly after RDM, but there are still key portions of ACN that aren't finished yet and that, in my opinion, make it unsuitable for real interoperability between different manufacturers...especially in the moving light world.

Why has there been a sudden push for RDM and not ACN?
There are a number of factors to that. I spent some time attending ACN meetings in the late 90's and got frustrated at the complexity and the slow progress at that time.

At the same time I had real situations where I needed some ACN-like features, but over the DMX line for our fixtures. I developed HES Talkback as a solution which was the basic core philosphy of how RDM works. Others in ESTA were facing the same situation I was and expressed interest in it, so we opened it up to start making it a real standard. We officially started in late 2001 on it.

We had a great group of highly motivated people and for a few years I had a lot more free time than I do now, so I was able to contribute a significant amount of time to do a lot of the heavy lifting on the project. We were all motivated to get it to market fast. Standards are slow to develop for a lot of reasons, but along the way we were able to find ways to optimize and speed up the process. These were all reasons for the "push" that you may have seen.

More recently, you are seeing the adoption start to pick up among manufacturer's. That is because companies are starting to design it into their new products and some are putting it in their existing ones now. Also, as more products start to appear, more people take notice and start to put it in their products. I saw evidence of a lot of this at PLASA. There are some huge players moving forward with RDM now.

Again, RDM is also much much easier to implement. Especially in something like a moving light so you're seeing it show up in a number of products now.

It doesn't hurt that a lot of us have been marketing it for several years now heavily too.

Does ACN work over DMX or is it only transferable over Ethernet networks?
ACN is pretty much limited to TCP/IP networks. It doesn't work over DMX.

I know ROBE fixtures have an ethernet port, does this support Ethernet neyworks or is it just for fix. updates?
I don't know the specifics of what ROBE is doing in their products with Ethernet. They may be using Art-Net.. I do know that they have been putting RDM into some of their products now though.
Scott M. Blair
RDM Protocol Forums Admin
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