E1.20 RDM (Remote Device Management) Protocol Forums

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-   -   RDM and lighting designers (http://www.rdmprotocol.org/forums/showthread.php?t=688)

Rob Anderson October 6th, 2008 06:29 AM

RDM and lighting designers
Does anyone know why knowledge of RDM seems to be such an alien concept to lighting designers. 99.9% of lighting designers know about DMX but i noticed at PLASA in london this year the RDM stand was almost completely deserted (at least when i was there). Do people think its true that lighting designers dont care about massive developments in RDM as they dont directly effect the "stage image" or is it that RDM is just too much too soon after the latest DMX512-A revision?


sblair October 6th, 2008 04:48 PM


A couple things. I think LD's aren't nearly as interested in RDM as Techs are in general. It is most directly useful for the Tech. It will take time for LD's to see the benefit to them, part of this requires products to mature and greater market saturation.

Also, it took a long time for DMX to catch on and even longer for LD's to know what it is and why it matters.

The RDM stand at PLASA was a buried a bit back in a far corner, but it accomplished a number of important things, which was for other Manufacturer's to see what is going on with RDM and the number of new products being released. It also gave us a great opportunity to plug a lot of different products together and see what worked and what didn't!

Rob Anderson October 7th, 2008 05:41 AM

I guess you could argue that DMX was more appliciable to techs back in the old days, with its origins in the problems with wire-per-dimmer control systems. But i doubt the fantastic moving light industry we have today would be possible without DMX, all i'm saying is that lighting designers need to realise what a huge shift the move to RDM will be and maybe if we can get some of the more brilliant minds in the lighting design world working with the brilliant minds in the control systems world we can speed up the development and implication.

Also whats happening with ACN? Where is the TSC in terms of progress on that, and wont that just make RDM over DMX obsolete?

sblair October 7th, 2008 08:04 PM

DMX took a number of years to 'take off.' DMX was released in 1986 with a small tweak in 1990. It wasn't until around '93-94 that you really started seeing it take off and moving lights starting to adopt it widely.

I've always said that major consoles will be some of the last products in the chain to add RDM support as that takes the most work to implement properly and console feature request lists are a mile long. It won't be until there is a critical mass of customers requesting RDM in the consoles until that bubbles to the top of the request list.

ACN has been officially released for a couple years now. It released shortly after RDM did. I have not seen a wide interest in it yet among manufacturers.

Rob Anderson October 8th, 2008 01:51 AM

I know this is an RDM forum, but why has ACN taken so long to take off then? And why has there suddenly been a push for RDM and not ACN. Is it just because of individuals pushing it like yourself and Mr. Howell? Does ACN work over DMX or is it only transferable over Ethernet networks? I guess manufacturers are happier taking small steps rather than larger leaps which might alienate and confuse their customers. I know ROBE fixtures have an ethernet port, does this support Ethernet neyworks or is it just for fix. uppdates?

Wow thats a whole lot of question marks, looks like i actually know nothing at all !


sblair October 8th, 2008 10:26 PM


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.

prwatE120 November 7th, 2008 07:31 AM

As co-ordinator of the various LDI and PLASA RDM demonstrations, I can confirm that the interest in RDM is both serious, and growing rapidly.

ACN will not replace RDM, as in many situations, the multi-drop RS485 infrastructure in getting wires to devices is far superior to the star network required of 10BaseT or 100BaseT Ethernet systems.

ACN and RDM will be complimentary protocols - indeed at LDI this year we saw a prototype LX console talking ACN to an ACN/DMX/RDM gateway, and thus presenting directly at the console the existence of a simple RDM enabled device at the far end of a DMX cable run.

Peter Willis

Milton Davis November 7th, 2008 11:28 AM

It should be noted that ACN and RDM are both likely to be around for a long time (as is DMX512-A). ACN will NOT make RDM oboslete. Both of the new protocols have their place and great pains have been taken to make sure that the two have some possability of working together as is evidenced by the various RDM/ACN bridge products.

At this point in time, it is less difficult and less expensive to implement RDM. Also, practical issues such as cable run length and connector reliability favor RDM. For extermely large scale systems with tens of thousands of end devices, ACN is very practical. In my typical situations which involve 1 - 16 universes of DMX, RDM is still my choice.

Milton Davis

Rob Anderson February 10th, 2009 07:59 AM

ACN question
I am slightly confused, i have been reading up on ACN but have not found the answer to this question

Is ACN a replacement DMX-over-ethernet standard, simply to provide a universal? Or is it a new layout based on TCP/IP?
Probably a simple question


sblair February 14th, 2009 06:07 AM


The answer is quite involved. There has been a recent thread over on Lightnetwork that I think explains the detail fairly well.


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