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Archive 1

Picture and text seem to contradict each other on contact numbering scheme

The text says, "When viewed head-on with the retention mechanism on the bottom, jacks will have contact number 1 on the left and plugs will have it on the right." The picture captioned "8P8C modular plug pin positioning" appears to show a modular plug with the hook facing away ("on the bottom"?), but contacts numbered from the left. That's certainly confusing. —Preceding unsigned comment added by 64.174.133.195 (talk) 16:46, 29 January 2009 (UTC)

It is the case that in Sizes and contacts, the statement: "If the connector has positions that do not have contacts, the remaining contacts are numbered as if all of the positions had contacts: for example, on a 6-position, 2-contact plug, where the outermost four positions do not have contacts, the innermost two contacts are numbered 3 and 4." is unconventional being inconsistent with and contraindicated by http://upload.wikimedia.org/wikipedia/commons/3/32/RJ14-pinout.png as well as Pinouts_2 which do follow standard conventions.
I believe the author intended to draw attention to the case where a 6P6C or 6P4C connector is attached to cable with a single pair of wires, essentially making a 6P2C connection, the outside contacts are still there but not used. Thus to identify the correct contacts to use the unused ones must be enumerated too. It is somewhat perverse to use connectors where the number of contacts are not the same as the number of conductors in the cable to which it is crimped. But, many 10/100 Base-T Ethernet cables often only have an 8P connector with pins in positions (notice I say "positions" not contacts) 1,2,3 and 6 since only 4 wires are needed (the cable is cheaper too since only half as much copper is needed). Now the coup-de-grace. There are also only 4 contacts (in the positions given), so is the contact pin in position 6, contact pin 6 or is it contact pin 4?! It IS pin 6 and therefore the case that positions are enumerated even though it is contact 4! This emphasizes the distinction of conductor pin identification by position or by contact enumeration. Both conventions are used and definitely confusing.
I think I am: 99.255.12.93 (talk) 01:32, 19 November 2010 (UTC) User talk:99.255.12.93
I checked the BSP documents which cover RJ11, RJ14, etc and the contact positions for those are labeled 2, 3, 4, 5 and simply skip 1 and 6. A 6P2C's two contacts would be positions 3 and 4, and a 6P4C would be 2, 3, 4, 5. Image:RJ14-pinout.png is indeed wrong and I've replaced it with Image:Conector RJ11.jpg. I've also redesigned the wikitable to remove the erroneous pin numbers. --Tothwolf (talk) 22:15, 19 November 2010 (UTC)

Merger proposal

We have three articles with substantially identical coverage of varying quality: Modular connector, Registered jack, and RJ11, RJ14, RJ25. None of them cites appropriate references, and all of them are in need of a great deal of cleanup work. Consolidating them will focus editors' attention on improving one article rather than dividing it amongst three. I propose we use the title Modular connector, with redirects for "Registered jack", "RJ11", and any other referents readers might reasonably be expected to search for. —Scheinwerfermann T·C15:14, 29 March 2009 (UTC)

I agree. Good plan- merging them makes a lot of sense. tedder (talk) 18:44, 29 March 2009 (UTC)
I've been on the fence on this one. I noticed the same thing with the number of articles some time back and put them on my watchlist. There are lots of related articles too. This might call for a major rewrite/restructure along with using the {{see also}} and/or {{main}} templates. My concern with Registered jack is that term is the original term (and is still a term used in communications) used for Bell System jacks and not just modular jacks so it probably does need it's own article. Registered jacks can also be other types of connectors, some are listed as "Uncommon types" in the Registered jack article, although some of those are in fact common in commercial markets and shouldn't be listed as an Uncommon type. I think this may call for working up an outline before ever moving content around...
Partial list of articles (not propsing to merge all of these, but they should all be evaluated to see how the final structure should play out):
--Tothwolf (talk) 19:51, 29 March 2009 (UTC)
Okeh, good comments. I agree with you that this is rather a big, tangled mess — good work compiling the list of involved articles. I don't think we need to let the size of the mess preclude our cleaning it up, i.e., merging at least some of these listed articles and redistributing information appropriately amongst those that remain. You've identified an important point regarding the fact that modular plugs and sockets are a subset of registered jacks, and I concur with your proposed solution (if I'm reading you correctly): fully cover modular connectors in their own article and use {{main}} at the top of their concise section in Registered jack. Of course, there would be an inline link to Registered jack somewhere near the intro of Modular connector (or whatever title we eventually settle on).
I'm concerned that we not let the unrealistic goal of perfection interfere with our achieving the realistic goal of improvement. Fortunately for our sanity in sorting out tangles like this, the most common status of a Wikipedia article is "unfinished"; we aren't expected to go from zero to perfected completion all in one go. As a first step, can we agree for now to put the full coverage of modular plugs and sockets in one article?
At the risk of tossing another ball in the air with the others we're already juggling, I revise my title suggestion to Modular plugs and sockets, which is more descriptive and less ambiguous. I draw inspiration here from AC power plugs and sockets, which bears our perusal as a model for how to handle a topic such as this present one with potentially unwieldy supersets and subsets, specialised variants, and multiple designations and national standards. —Scheinwerfermann T·C00:29, 30 March 2009 (UTC)
Yes, what I was trying explain with Registered jacks is Bell used certain configurations of modular plugs and jacks for their Registered jack scheme, but they also used other connectors, especially for multi-line applications. I have some of the original Bell System BSP books here that cover some of this that may be helpful when sorting out the Registered jack article.
I don't think renaming Modular connector to "Modular plugs and sockets" would be a good idea. The industry standard term for these is modular connector and unlike the electrical industry where there is a huge variation for power connectors, modular connectors (even if often referred to by the wrong names/terms) are fairly standardized.
There is also the DEC Modified Modular Jack (MMJ) connector, which is an offset tab type of 6P6C modular connector (the 6P6C itself often erroneously called RJ11, RJ12, RJ16, etc). MMJ should probably retain it's own article as it is a specialized application and much like Registered jack there is a lot of material that could be added to expand that article (there were all sorts of adapters, cables, etc). Oddly enough, the very same offset tab 6P6C modular connector used for DEC MMJ is now used for the Smart antenna jack for digital television converter boxes per the EIA/CEA-909 standard (although with a very different pinout— plugging a DEC MMJ serial cable/device into the Smart antenna jack would likely damage the serial device). Lego Mindstorms NXT uses a similar offset tab modular connector (the photo in the article is wrong as it shows a standard 6P6C), but the tab is offset to the opposite side when compared to the offset tab 6P6C modular connectors used for DEC MMJ.
--Tothwolf (talk) 02:46, 30 March 2009 (UTC)
In thinking about this a little more, this project might really be more of a two or three stage project. Clearly the BSP type RJ material should go into Registered jack, with {{R from merge}} redirects pointing to the individual sections (the exception being RJ45, see below). These sections in Registered jack should then use a template pointing to the USOC/industry term such as 6P6C, which is itself a redirect to the specific section of Modular connector discussing that specific type of connector with information on the different uses (including a wikilink to the RJXX type). It will be important to use the original articles such as RJ11, RJ14, RJ25 (some of the others that were merged together are already redirects too) when redirecting to Registered jack with the {{R from merge}} template in order to maintain GFDL compliance.
For 8P8C and RJ45 it will get tricky. People regularly search for RJ45 when searching for Ethernet connector information so RJ45 really should redirect to the full article on TIA/EIA-568-B (where both 568B and 568A are discussed) with the pinout for that particular use of the 8P8C connector.
The 8P8C is also mentioned in Electrical connector, which uses a template to point to the 8P8C article. I also noticed in 8P8C#Types something very wrong with the Western Electric/Stewart Stamping and Tyco/AMP information. The actual pin spacing of the connectors is identical (they plug into the same 8P8C modular jack). The difference is where the strain relief is crimped. The WE/SS and AMP types use a slightly different position for the strain relief crimp, so the die cavities are slightly different and trying to use one die on the other type of plug will crush and damage part of the plug. It is also stated that "All Tyco/AMP 8P8C plugs include a metal ferrule, and so shielding comes standard."— this is false. Tyco/AMP plugs are available in both shielded and unshielded types, both of which are extremely common, the unshielded type has no such metal ferrule. (Stewart connector was purchased by Belfuse a number of years back and AMP was purchased by Tyco, in case someone needs to look up information.)
There may be material in some of the older revisions of these articles that could be useful as well, such as with the 8P8C article: [1] [2] [3]
There are also 10-position modular connectors that are physically similar to the 8P8C. Sometimes people refer to these as 10-position RJ45s. They have 10 contacts instead of 8 and are available in both the WE/SS and AMP types, both shielded and unshielded.
I also noticed an unfinished merger for Ethernet crossover cable and Crossover cable. I've not even tried to dig into the revision history on these to sort them out yet.
Here are some links that may help with this stuff too:
Hopefully all this information helps more than generate even more questions. This is why I'd not yet attempted to sort this stuff out though :)
--Tothwolf (talk) 04:55, 30 March 2009 (UTC)
While making a few minor changes to some of the existing redirects, I discovered there is already a 10P10C article that could be merged into Modular connector. Tothwolf (talk) 20:36, 30 March 2009 (UTC)
I've updated and added the merge templates to the various articles and added a split template to Registered jack. I'm not really sure if we should split the list of registered jack types into it's own article or not yet (we should probably see how large the merged version is first) but its one possibility. Tothwolf (talk) 22:43, 30 March 2009 (UTC)
It appears others were working on sorting these out back in 2006. Talk:Registered jack#Naming Confusion has more information. Tothwolf (talk) 03:30, 31 March 2009 (UTC)

I agree the "RJ45" article is not needed, but possibly it would be unwise to leave a redirect from RJ45 to an article. A disambiguation page (or redirect to one) would be appropriate, to prevent inappropriate inbound links. Incnis Mrsi (talk) 11:19, 20 July 2011 (UTC)

Agree. The actual, hard, legitimate RJ45 standard was of little historical use and almost no modern use, but the name is synonymous with 8P8C today. I do agree, however, with Incnis Mrsi that RJ45 should remain as a disambiguation page. Msaunier (talk) 05:16, 10 August 2011 (UTC)
I object to the continued presence of the merge tag on this article. 8P8C is not synonymous wiht RJ45; the modular connector article should state that Rj45 is a widely used nickname for an 8P8C modular connector but the registered jack uses a keyed connector and specifies a particular wiring pattern not relevant to Ethernet connectors. --User:Wtshymanski, 16:39, 7 September 2011 (UTC)

Modular Jack Wiring needs Clarification

I went to this article to try and be exact about how I was wiring my phone connectors. (Yeah, I know. Just get a cell phone and forget about it.) Overall it's a terrific and very helpful article. Nice work! But there is some confusion.

The instruction for Modular Connector/Pinouts shows pin placement described as "Holding the connector in your hand tab side down with the cable opening toward you, the pins are numbered 1–6, left to right." If that's the case, then attaching both 6P2C or 6P4C connectors, one for each end, per the color/number assignment under "pinouts" will cross the wires once both ends are plugged in. They need to be mirror images. In the "Telephone Plug" article it suggests: "When modular connectors are used, the "latch release" of the connector should be on the "ridge" side of flat phone wire in order to maintain polarity." That method keeps the cable aligned and not crossed-over, but when looking "tab side down with the cable opening toward you/me"; one has the red on the left at Pin 3 and one has the red on the right at Pin 4. Curiously, this means that when the cord is plugged into the jack, one end of the cord will match the jack wiring and one will be the mirror opposite. Does this mean it doesn't really matter whether red is Pin 3 or Pin 4?

In conclusion, somewhere in the article, preferably under "Pinouts", it should clearly say that, when putting on connectors they need to be attached as mirror images; one with the red on the left at Pin 3 and one with it on the right at Pin 4. RobertL39 (talk) 23:21, 24 March 2012 (UTC)

Electronic Filtering

There is no information about the electrical filtering. There are 8P8C connectors with Common Mode Choke. This is a coil on a ferrite ring that helps to filter out high frequencies (low pass filter) and to remove the noise, but will keep the differential signal unchanged. See: http://katalog.we-online.de/kataloge/eisos/index.php?language=en&pf=WE-LAN_RJ45_HPLE and http://www.raspberrypi.org/archives/781 and http://en.wikipedia.org/wiki/Choke_%28electronics%29 — Preceding unsigned comment added by Mircea.Vutcovici (talk • contribs) 18:50, 17 August 2012 (UTC)

Your first two links are for devices that include integrated isolation transformer (and choke) specialized for Ethernet over twisted pair. --Kvng (talk) 13:07, 19 August 2012 (UTC)

physical dimensions

No physical dimensions given at all under the size heading. And that was what I was looking for. Just got calipers out and measured 4P4C plug at 9.75 wide 7.75 high (to top of jack) pins seem to be spaced on 1mm centerlines. Might it be an idea to put this kind of information in? --82.47.140.47 (talk) 14:35, 25 September 2012 (UTC)

Your measurements are problematic due to WP:OR. I've added dimensions with a reference. -—Kvng 13:18, 28 September 2012 (UTC)

8P8C Numbering

Note that 8P8C numbering is 2-9, not 1-8.  The latter is a lamentably common mistake.

38.69.12.6 (talk) 16:03, 27 July 2015 (UTC)

To me, it sounds like that would be for a hypothetical 10P8C connector (cf. the numbering of a 6P4C), which might actually end up being the exact same physically as an 8P8C (did not check this, it's a hunch). Can you provide a reference that an 8P8C is numbered 2-9? Digital Brains (talk) 18:08, 27 July 2015 (UTC)
I checked ISO 8877 mentioned in the text. The standards document NEN-ISO/IEC 8877:1992 says on page 2: The contact number assignments are given in the table. The table on page 2 then clearly numbers the contacts 1-8. The text then discusses in section 7 the 4-wire ISDN basic access TE cord, where they number the contacts 3-6 as expected. Note that even though this article mentions ISO 8877 as the international standard for this connector, that's unfortunately not entirely correct. ISO 8877 is specifically about the ISDN Basic Access Interface, and refers to IEC 603-7 for, I quote, complete detailed specifications of the plugs and jacks. Unfortunately, I don't have access to that document or ANSI/TIA-1096-A, so ISO 8877 is what I have to work with. But to conclude: a good source numbers the contacts 1-8, not 2-9. So I think the contacts are numbered 1-8. Digital Brains (talk) 18:34, 27 July 2015 (UTC)

Pin number photo

This shows two plugs facing in opposite directions, but with Pin 1 on the left of each. The top one is erroneous and should be removed. (This is separate from the question of which wire goes to which pin). G7mzh (talk) 10:45, 7 July 2017 (UTC)

If you look closely you will see that the connectors are rotated around the horizontal axis, so everything's fine. --Zac67 (talk) 10:59, 7 July 2017 (UTC)

RJ45/8P8C incompatibilty only one way

An 8P8C plug will physically mate with a true RJ45 jack, although the reverse is not true. It isn't that uncommon to see equipment with the notch cut out for a true RJ45 connector but a regular ethernet lead connects to it without issue. I have a couple of switches with such notched connectors and it seems quite common for RJ45<->D-Sub adapters to have the notch. Crispmuncher (talk) 04:24, 15 May 2011 (UTC).

Keyed 8P8C connectors are readily available and can be used for other applications as well. They were not limited to just "telephone RJ45" use. A standard non-keyed 8P8C plug will plug into a keyed 8P8C jack, but a keyed 8P8C plug cannot be plugged into a non-keyed 8P8C jack. --Tothwolf (talk) 06:25, 15 May 2011 (UTC)
I should also mention that keyed 10P10C connectors also exist. APC used these for the USB cables for some of their UPS. The 10P10C jack on the UPS could be used with either a serial cable or a USB cable. The keyed 10P10C plug of the USB cable prevented someone from connecting the 10P10C plug of the USB cable to an 8P8C telephone or network jack (which in the case of a telephone jack, would have damaged whatever USB port the other end of the cable was connected to). --Tothwolf (talk) 21:54, 15 May 2011 (UTC)
I find this to be both absurd and absurdly worded. Every comment in every magazine from 1984 to 2000, along with every package of both plugs and receptors in every store used the term RJ45. Indeed, the RJ45 designation commonly refers to any 8P8C modular connector for application in computer networking (Ethernet). Specifically, the term "RJ45" is synonymous with "8P8C, keyed." Indeed, "A Registered Jack (RJ) is a standardized telecommunication network interface for connecting voice and data equipment to a service provided by a local exchange carrier or long distance carrier. Registration interfaces were first defined in the Universal Service Ordering Code (USOC) system of the Bell System in the United States for complying with the registration program for customer-supplied telephone equipment mandated by the Federal Communications Commission (FCC) in the 1970s.[1] They were subsequently codified in title 47 of the Code of Federal Regulations Part 68." The term, "8P8C" didn't appear until decades later. Even Grainger, one of the leading suppliers of Ethernet connectors and cables, synonymizes "RJ45 - 8P8C." Again, it is absolutely absurd to attempt to subvert common nomenclature with something pathetically absurd as "8P8C." More to the point, "Registration interfaces were created by the Bell System under a 1976 Federal Communications Commission order for the standard interconnection between telephone company equipment and customer premises equipment. These interfaces used newly standardized jacks and plugs, primarily based on miniature modular connectors." The "RJ45" part is referred as the "Code," whereas the "8P8C" part is referred to as the "Connector." I understand the keyed and un-keyed issue, so hush. I've also seen countless architectural plans and network wiring diagrams laid out by architects and network engineers, and they always specified the jacks as "RJ45." Not ONCE did they every say, "8P8C" or "8P8C - keyed." Someone please stop this idiotic Internet hijacking of industry standards! Thank you.Clepsydrae (talk) 22:19, 1 September 2017 (UTC)

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Invention

We need a good WP:SECONDARY source or two to establish the inventor of this connector. A patent is a WP:PRIMARY sources and determining who was first from patent dates is WP:OR. There have been a couple patents cited through different versions of the History section: U.S. patent 3,789,344, U.S. patent 3,860,316. U.S. patent 3,699,498 is mentioned above.~Kvng (talk) 14:28, 31 March 2018 (UTC)

It certainly won't be an outsider of the Bell System, as suggested by the previous version. That wasn't even the same connector. Hardesty of WECo produced the series of patents that is the true basis. But the section does not actually make any claim about inventing it. There really was not a single inventor. Krumreich also was an early participant, and filed other designs as well (e.g., the Trimline connectors).Kbrose (talk) 18:29, 31 March 2018 (UTC)
Kbrose has restored his edits. I trust Kbrose better than the unknown editor(s) who originally added this material so it can stay this way for now as far as I'm concerned. We still need to find a WP:SECONDARY source though. ~Kvng (talk) 14:02, 1 April 2018 (UTC)
Point about secondary source is well taken, but so much of the technical details of US telephony history is only in primary sources, presumably because of dominance of a single provider. There may be some more 'public' references for the early modular connectors used on the Trimline series, because of the importance of that design. I believe the first patent of those is dated in 1965. Kbrose (talk) 14:23, 1 April 2018 (UTC)

rare

The article says Other than telephone extension cables, cables with a modular plug on one end and a jack on the other are rare. Since a cable with male on one end and female on the other is pretty much an extender, of course they are rare. Gah4 (talk) 08:09, 23 December 2018 (UTC)

This is about intended use. There are few applications (I don't know any) where the standard cable has a plug on one end and a jack on the other, while this is a fairly common arrangement for, e.g., D-subminiature cables. If the cable were straight-through you could indeed use such a cable as an extender as well. Digital Brains (talk) 09:45, 23 December 2018 (UTC)

Category 6A cables with shielded modular connectors

I don't see any discussion of the modular connectors used with cat6A cables (10GBASE-T), which seem to contain a metal shield that wraps around three sides of the connector (and may have other internal changes or shielding). My understanding is that this is to improve the Near-End CrossTalk (NEXT) specs compared to the modular connectors on cat6 cables. Anyone have good references on this stuff? Gnuish (talk) 09:05, 14 March 2020 (UTC)

Category 6A (capital A) cables are unshielded. Shielded cables or connectors are out of spec. --Zac67 (talk) 10:54, 14 March 2020 (UTC)
OK, the cables may be unshielded, but cat 6A also requires different connectors (and jacks and patch panels) than cat 6. The connectors have metal shields around the outside, and connect to a drain wire in the cable. See this reference for example: https://www.platinumtools.com/sections/blog/datacom/how-to-terminate-cat6a-connectors-in-the-field/ (That page says there may be a foil shield on the cable as well as a drain wire, by the way.) Also, https://www.amazon.com/Cable-Matters-50-Pack-Shielded-Modular/dp/B00E4OCOUW has some great pictures of these metal-shielded connectors. https://www.diffen.com/difference/Cat6_vs_Cat6a is another reference which says that "cat 6A cables are also often shielded". The relevant ISO standards seem to be unavailable online, via the typical standards monopoly publishing practice. This "Modular connector" article does not describe these new connectors, or the reasons for them, though they are modular connectors and are completely interoperable with the 8P8C modular connectors used for 1-gigabit and 100-megabit Ethernet cables. Can we improve the article to discuss them? Gnuish (talk) 07:18, 21 April 2020 (UTC)

Replace incorrect images?

Can we get images illustrating T558A and T568B wiring without the false “EIA/TIA-568A” and “EIA/TIA-568B” text in the images? The standard that defines T568A and T568B was called “TIA/EIA-568” originally, then “TIA/EIA-568-A” followed, then “[…]-B” and “[…]-C”, then “ANSI/TIA-568-D”. All of them identically define the two wiring layouts T568A and T568B. There has never been any such thing as a TIA-568-A or TIA-568-B layout because all versions of 568, versions null through D so far, define both T568A and T568B, and all do so identically. Stephan Leeds (talk) 09:09, 26 January 2021 (UTC)

Diagram showing pin positions would be nice

"The positions of a jack are numbered left to right, looking into the receiving side of the jack with the hook side down, starting at 1."

It would be nice to have a diagram actually showing the pin positions. I am not sure what is meant by the receiving side of the jack. Must be side where the cable goes into the jack but I am not sure.

Labeled picture in Modular connector § Size and contacts. ~Kvng (talk) 16:21, 24 July 2023 (UTC)
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