|This is the talk page for discussing improvements to the DMX512 article.|
|This article is of interest to the following WikiProjects:|
|This is a current Stagecraft collaboration!
Please help improve it to match the quality of an ideal article as shown in the article guidelines.
Please help us to maintain consistency in the article by following the style standards detailed above.
- 1 3-pin XLR Connectors
- 2 Use of bold+italics
- 3 Page name should be changed
- 4 Randomness follows here
- 5 DMX-512A
- 6 Protocol specification
- 7 section on art-net?
- 8 alternative sockets
- 9 Requested move
- 10 Add acronym definition for DMX
- 11 Direct quotes from standards
- 12 Just the facts -- it's not a howto
- 13 3-to-5 adapters: Should the unused pair be spanned through?
3-pin XLR Connectors
I'm sorry, why do I need a "citation" if I state that the vast majority of Dmx-compliant products the world over have 3-pin XLR connectors exactly like the ones used in audio? Is that my opinion? No: It's a fact. It's all over, anybody can see it. Go to any manufacturer's website and check out the rear panel description. Any price range. The 5 pin got lost somewhere on the way, and only higher-end products provide it, ALONG with the 3-pin. Not my fault. We can't have citations all over the place, it's moronic. If you know something and it's a known fact, you state it; if it smells fishy, drop a citation, but if it's common knowledge, what the hell? — Preceding unsigned comment added by 184.108.40.206 (talk) 20:49, 29 June 2011 (UTC)
- DMX is now widely used by architectural lighting systems, ranging from the lights under kitchen cabinets to the lights illuminating the exteriors of buildings to the pixels in some big electronic billboards being three DMX devices per dot. Virtually none of that stuff uses XLRs. -- 220.127.116.11 (talk) 05:53, 20 July 2011 (UTC)
Because you are wrong. Quite simply, the 3-pin XLR connector is *specifically* prohibited by the E1.11 standard. Therefore, devices fitted with a 3-pin XLR connector are demonstrably non-compliant.
Some reputable manufacturers still use 3-pin XLR connectors on some of their current designs - notably Martin Entertainment - and they provide both 3 and 5-pin connectors as they know it's not permitted and are only doing it on some of their lower-end devices because their first devices used the 3-pin for the proprietary Martin communication protocol they were using prior to USITT DMX512-1990.
There are indeed a lot of cheap knock-off fixtures that use 3-pin connectors. Most of those don't comply with the data portion of the standard either, using such things as framing-error to detect the Break instead of the actual timing, and they are often incapable of accepting DMX data transmitted outside a very narrow range of timings.
- Personally I believe these mistakes are because the Microchip PIC App. Note example code for DMX 512 reception has these particular flaws. Of course, that's personal opinion so doesn't count on Wikipedia. — Preceding unsigned comment added by 18.104.22.168 (talk) 20:09, 28 September 2011 (UTC)
Use of bold+italics
Could the article do with less use of bold+italics in the first half of the article? It seems to make it harder to read.— Preceding unsigned comment added by 22.214.171.124 (talk • contribs) 18:03, 24 June 2005
Page name should be changed
Javid Butler 09:35, 23 February 2007 (UTC) Page name should be changed to DMX512, which is the only name the protocol has ever had.
- I aggree with you the name should be changed to the generic name, DMX512-A refers only to the 2004 revision of DMX512 and the article deals also with older revisions so the title is at least a bit misleading...
- --Keeper of the Keys (talk) 10:23, 26 March 2009 (UTC)
Randomness follows here
- Wikipedia isn't a web directory! Why must we link to every person's random page with some small bit of random information remotely related to the subject? I don't even know what AVR is and I'm a professional stagehand, using DMX every day. I'm going to remove all the links from this article that aren't links to the standard or to the related organizations. Also, check out Wikipedia:External links#Links to normally avoid, especially note item #9. kmccoy (talk) 05:17, 6 March 2006 (UTC)
- As I stated above, I've trimmed the external links. I am copying the ones I removed to this page.
- DMX Control Software
- @Kmccoy: I'll respect your decision.
- AVRs are 8bit microcontrollers and quite common. (BTW: Those external links are worse the those you kicked...) My code would be useful for people developing costum devices. So the Pages of Ujjal, Hippy (and my own) could be more useful then the official ones... Hendrik— Preceding unsigned comment added by 126.96.36.199 (talk • contribs) 07:31, 6 March 2006
- This page as of March 8, 2006, is very complete and accurate. Wish I'd looked here first! Regards Terry King —Preceding undated comment added 19:22, 8 March 2006.
- Is there enough material to make an article about DMX implementations? /Olle 17:30, 4 September 2008 (UTC)
Could we please have some more information about DMX-512A? Tompw 13:39, 12 March 2006 (UTC)
This page has lots of information but lacks detail on the core part: the protocol itself. The protocol has a break signal, a mark after break, a start code, with their respective minimum and maximum timings. The rest are unimportant details. Motumboe (talk) 16:33, 13 November 2008 (UTC)
section on art-net?
One of might lighting pals says that art-net is a way of doing DMX over Ethernet - and it does a whole lot of wacky things. If anybody who knows about the subject could add a section, it'd be nice. --moof (talk) 03:19, 30 January 2009 (UTC)
Hi, anyone know if other common sockets get substituted much for the 5 (and 3) pin XLRs? I've been asked to make up an extension lead for stage smoke machine controller, but there doesn't seem to be much information available - it's own user manual is particularly usless, offering just 3 pages in each language, on basic setup and use. Thing is, it uses a 5-pin DIN socket.... hmmm. So, much likelihood it's DMX compatible and they were just trying to save a little cash and lock you into proprietary equipment/spares, or would it be completely custom? (Trying to do the job cheaply and efficiently is proving difficult, and I'd rather not run into some of the listed problems e.g. using the wrong impedence of cable). If there's a chance this is the case, I can go add the fact to the appropriate part of the mainpage also :) 188.8.131.52 (talk) 15:15, 3 March 2009 (UTC)
- I had a similar fog machine. If it doesn't have a way to set a DMX address, it is not DMX compatible. I have used DMX cables as an extension however. I ran cable from our booth to the center wall of backstage (about 175 feet) and then using spare DMX cables we can connect the fog machine anywhere around the stage. That cable has been used for almost 3 years now with no problems. The fog machine eventually died (it was 12 years old after all) but the heater was the problem, not the control. Now we just have an extra DMX run to the stage. -JWGreen (talk) 16:12, 3 March 2009 (UTC)
Add acronym definition for DMX
Can we add a sentence saying that DMX stands for Digital MultipleXing? I think that is appropriate, but I don't know the rules. —Preceding unsigned comment added by 184.108.40.206 (talk) 18:25, 17 December 2009 (UTC)
- Yes, but an authoritative source should be cited for such a statement. Lambtron (talk) 16:14, 18 December 2009 (UTC)
- I have found a source. "DMX512 comes from Digital Multiplex with 512 individual pieces of information." http://www.usitt.org/DMX512FAQ.aspx#a1 I believe it to be authoritative because the USITT concieved the protocol.220.127.116.11 (talk) 02:03, 23 December 2009 (UTC)
Direct quotes from standards
Some editors have shown a propensity to insert problematic, direct quotes from the DMX512 standard. I've tried to clean these up, but they keep popping back into the article. I don't want to offend, and I certainly don't want to start an edit war, so I will explain my thinking here and leave it to others to decide the validity of my thinking and take appropriate action. A case in point:
DMX512 data are sent using EIA-485 voltage levels. However, quoting from E1.11,"The electrical specifications of this Standard are those of EIA-485-A, except where specifically stated in this document. Where a conflict between EIA-485-A and this document exists, this document is controlling as far as this Standard is concerned."
There are several problems with such quotes, and this quote in particular:
- Verbatim duplication of any part of a copyrighted standard may violate its copyright.
- The purpose of this article is to explain DMX512. If the standard contains a statement that embodies an important idea, the editor's job is to integrate that idea into the article, not simply quote it verbatim. It's already been made abundantly clear that a standard exists, and where to find it, so anyone interested in the exact wording and details of the standard can read it there.
- The idea embodied by this quote is useless unless it is supplemented by at least one related example. It's like stating "the sky is always blue, except where it is red", without explaining where or under what circumstances the sky might be red.
- Even if it were adequately paraphrased and given meaningful context, this statement lacks a valid citation.
Just the facts -- it's not a howto
It seems to me that discussion of DMX512 operation without terminators falls under WP:NOTHOWTO (e.g., "For short cable runs of less than about 45 metres (148 ft) with only a few devices, it is sometimes possible to operate without termination."). Many other tips and tricks could be given here, but they are all outside the scope of the DMX512 specification and standard practice. I propose that all such statements be removed. Lambtron (talk) 15:23, 8 July 2013 (UTC)
- The obvious HOWTOs such as the standard spec and the manufacturers instructions all obviously say "use a terminator" and "don't use mic cables". However it's common knowledge to anyone handling DMX that both of these rules can be ignored successfully. I see it as encyclopedic for WP to recognise both of these facts, and to comment (in an encyclopedic manner, without breaching NOTHOWTO) that both can be skipped and that this will work for small setups and fail for large setups. We might even (still in the same scope) note that the practice of duplicating channel addresses also works, but that this one will also work reliably on large setups. Andy Dingley (talk) 16:42, 8 July 2013 (UTC)
- I can think of numerous, commonly known ways to violate the DMX512 spec and still have a functional network; should they all be discussed in the article? For example, should we mention that it's sometimes possible to directly drive a DMX512 network with an RS232 driver? IMO, even though it may work sometimes, a practice that violates the spec and deviates from industry standard practice doesn't belong here -- unless RS confirms it to be a widely used practice. Otherwise it's nothing more than a hack HOWTO, no matter how it's rephrased. In any case, RS is essential here. It's still a hack even if backed by RS, but at least I'd get the feeling it belongs in the article, perhaps in a section called "Common hacks"? Lambtron (talk) 19:32, 8 July 2013 (UTC)
- Wikipedia is NOT meant to be just a repeat of official specifications. In the same area of the article that it discusses terminations per the spec, you can describe alternate configuration that work, especially if you have reference(s) or article(s) that backs up your statements. If people still don't like it, then add a link to a good article in the External Links section. • Sbmeirow • Talk • 20:00, 8 July 2013 (UTC)
I agree that the article is NOT meant to be just a repeat of official specifications. It is also not meant to be a repository of hacks, which are fundamentally HOWTOs. That being said, I agree with Sbmeirow's statement, amended as follows: "you can describe alternate configurations that work if you have reliable sources that back up your statements."
If terminator and cable hacks are common practice, surely there must be RSs that confirm that? Also, it's almost meaningless to say that a hack works "sometimes" with "a few devices" and "shorter cables"; such vague generalities should be rewritten as enclopedic facts. Perhaps RS can help with that? As a reader, I'm also interested in knowing who uses these hacks, and why they would choose to use them instead of the (apparently) more reliable standard practice. Lambtron (talk) 14:32, 9 July 2013 (UTC)
3-to-5 adapters: Should the unused pair be spanned through?
When dealing with 3-pin DMX equipment, and trying to correct the mess they make to the 5-pin XLR standards, should the unused pair for future use be bridged across the device for standards compliance?
This would take the form of an H-shaped pair of 3-to-5 barrel adapters or a W-shaped pair of 3-to-5 pigtails, with a short cable running between them to span the second pair.
A second question is regarding shielding of this spanned pair. I assume it should be shielded, so that's not really at issue. The question is about ground loops. Should this shield attach only at one end of 5-pin connectors, since it is already passed through the 3-pin DMX device? Or should grounding the second-pair shield to both 5-pin connectors not matter, being right next to the 3-pin DMX device?