However, you can get weird Dsub connectors with things like COAX in there, so having the shell sizes have names can be useful.
DE with 2 High current contacts:
https://de.wikipedia.org/wiki/D-Sub#/media/Datei:D-Sub_conne...
DE with 15 contacts ("VGA"):
https://de.wikipedia.org/wiki/D-Sub#/media/Datei:D-SUB_DE-9-...
My theory is just that the cables came in the box and are screw-on when more modern connectors are friction fit, and the IT departments don't want the hassle of "they just got pulled out." Which should have been predictable - but I can literally see 12th gen Intel, paired with 1080p display, over VGA fairly regularly.
Source: Too many years experience in the desktop support trenches.
A single letter doesn't have a lot of meaning on its own, and the A-E order is not consistent with the E shell being smaller than all the others.
By making it fully adjacent to the 'D', it makes the letter sound like it's part of the standard's name, like the 'RJ' in 'RJ45'.
It would have been better to focus on pin count and row count, as those along with standard pin spacing drive the shell size.
D-2R-15 for a two row 15 pin connector equivalent to DA-15, D-3R-15 for a 3 row 15 pin equivalent to DE-15 / VGA.
Could trim out the 'R' and go with "D2-15" for 2 row and "D3-15" for 3 row, if brevity is preferred.
It’s early and eyes are still a little blurry, but I’m not seeing a cite?
Wikipedia fleshes it out a bit:
The D-sub series of connectors was introduced by Cannon in 1952.[3] Cannon's part-numbering system uses D as the prefix for the whole series, followed by one of A, B, C, D, or E denoting the shell size, followed by the number of pins or sockets
No links to a primary source, but seems plausible.
Standards that ignore human frailties will be corrupted by humans, and that's a good thing.
If you ever find yourself wanting to order the connectors or backshells, it might be useful to know it's actually DE-9.
DB15 is the only one I have issues with. The company I work with has one container with "DB15" connectors (DA-15), and one with "DB15HD" (DE-15)
J3 is an 8P8C jack (commonly RJ45) for IEEE P802.3bz 2.5GBASE-T communications, backward compatible with Gigabit and Fast EthernetWhy wouldn't you say RJ45?
RJ11, RJ14 and RJ25 all used the same 6P housing though, making them 6P2C, 6P4C and 6P6C connectors, respectively.
Things sold as RJ11 is often 6P4C, making for another error. The rule of thumb is that anything referred to as RJ-something is likely wrong.
The regular ethernet 8P8C connector was defined by both an ANSI and ISO spec, neither of which gave the connector an actual name as it covers modular connector designs. :/
Closer is RJ38X, which is a series 8-position jack, not a normal 8-position jack. ("Series" means that the jack shorts pint 1 to pin 4 and pin 5 to pin 8 when there's not a cable plugged in to it; you would be able to fit an "Ethernet" connector into it, but even so it's probably not what you want.)
AFAICT (skimming 47 CFR part 68, and the historical AT&T documents that became 47 CFR part 68), there is no RJ-number for a normal 8-position jack.
Because of the size being different? Surely a keyed female plug will take a male connector with or without the key. Or did you mean you couldn't fit a RK45 connector into a Ethernet plug because then the key would interfere?
https://www.govinfo.gov/content/pkg/CFR-2000-title47-vol3/pd...
Unfortunately, the “RJ45” part of these codes has become a metonym for the unkeyed version of the miniature eight-position jack and plug, now widely used for Ethernet and other purposes, but strictly speaking, RJ45 refers to a different connector with totally incompatible wiring.
Pedantically speaking, RJ45 (as first defined by AT&T internally[1], and later by the FCC's 47 CFR part 68) is not that. The RJ45 socket is a keyed 8P8C modular jack, not a regular 8P8C modular jack. Here is a photo: https://commons.wikimedia.org/wiki/File:RJ45_female_connecto...
[1]: The "RJ45" designation was originally an AT&T "USOC" (Universal Service Order Code). In the '70s, the FCC told AT&T that they had to allow interoperability from other companies, so the FCC had to publish a bunch of specifications; the meaning of "RJ45" became publicly specified in Bell System Communications' Technical Reference PUB 47101 "Standard Plugs And Jacks" (1979, though I think there might be an older number/revision from the early '70s that I haven't been able to track down). That (in combination with a few other technical references, such as PUB 47102), later became part of the Code of Federal Regulations, as 47 CFR part 68.
It took a few tries to get it right, but it's amazing that PoE is even an option given how far it is outside of the scope of what the cables and connectors were designed for. I've heard of locations that use it for power, instead of 120 V outlets, because it's cheaper and safer and most portable high-current appliances use batteries, while fixed high-current appliances use 240 V outlets.
Hot plugging is always a challenge, especially with direct current, and negotiation prevents that from being a problem while making a connection, but I never considered that unplugging isn't negotiated first. I wonder if IEC has ever considered using a locking latch, like an EV charger.
I have a PoE camera that I sometimes unplug to restart it, when it freezes up and I can't restart it from the web interface. I'll be sure to turn that port off first, before unplugging it.
I didn't learn this until this year...
Is Mate-n-Lok perhaps a compatible product from a competitor?
1: https://community.intel.com/cipcp26785/attachments/cipcp2678...
Like "Kleenex" means any facial tissue that is meant to be sneezed on.
(Both uses are wrong, but both also tend to promote efficient communication.)
https://www.reddit.com/r/electronics/comments/ioc6sf/i_final...
So it's really not uncommon to have manufacturers make something thing that a different company is known for. I think it's basically just luck that Molex got the credit for it
100% guilty here, ouch.
also never saw a 8P8C "keyed, real rj45" connector in person.
Right, in your average 2020s home or office, "Ethernet" is almost certainly 8P8C (commonly known as RJ-45). In decades past it was more ambiguous – in the 1990s, coax – ThinNet/10Base2 – was still reasonably common; even the older ThickNet/10Base5 would still occasionally be encountered. So to some extent, being specific is a bit of an "old timer" trait–a habit picked up decades ago when it was still important, now maintained when it is rarely still necessary.
But even in the 2020s – in a factory, it could easily be M12 instead. Or even a mix of both – 8P8C in the offices, but M12 on the factory floor.
Honestly, even in a home environment, I hate how fragile and easily unplugged 8P8C connectors are (the worst part is when they get slightly pulled out, so they still look like they are plugged in, but the connection is dead or flaky). I've thought about using M12 at home before, but it probably wouldn't be very practical.
"Standard" originally meant "an extended pole holding a flag or other marker" from the Latin "standardum" by way of French's "estandart".
Now "standard" means "level of quality or attainment".
Things change. Deal with it.
It's DB9.
Also, it's RJ45. Nobody cares what the real name is.
In the entire history of humanity's ability to think and understand, exactly and precisely 0 people (ever) have been confused by either of those terms being used incorrectly.
Because we codified the nomenclature, the difference is important, and the standard "serial port" is a DE9 and nothing else. The word "standard" wasn't codified, but D-sub connectors were.
D-subminiature connectors are codified by both IEC 60807-3 and MIL-DTL-24308K.
Neither IEC 60807-3 nor MIL-DTL-24308K "standardize" or "codify" D-subminiature connectors into DA/DB/DC/DE sizes.
Is there an actual standard referencing DA/DB/DC/DD/DE? It wasn't linked in the article.
I do not think there is, and I think that everyone claiming that DA/DB/DC/DD/DE is a "standard" is wrong.
After all, we 100% DEFINITELY want to be "correct". Words like "standard" have meaning.
It appears DA/DB/DC/DD/DE is just a trade practice started by Cannon. Maybe that's why the "standardized" and "codified" specifications refer to sizes 1 through 5 (or 6).
If we want the opinion of the ultimate arbiters of standardization, both Digikey and Mouser adhere to "the standard" by organizing shell sizes into IEC 60807-3 and MIL-DTL-24308K-compliant numerical sizes with letters in parentheses to denote that the letters ARE NOT a standard.
The most likely reason that DA-DE sizes are not in the standards is that DA-DE were once trademarks or otherwise proprietary designations created by Cannon. Indeed, practically the only consistent and quasi-official spec sheets that list the A-E sizes are published by ITT Cannon but even they reference the actual standards (e.g. "E Size 9 (MIL-DTL-24308 Size 1)").
I assert that DA-DE are proprietary designations created by Cannon (now ITT Cannon) and calling them a "standard" is incorrect, IN AN ENGINEERING CONTEXT.
In support of my position I have referenced both IEC 60807-3 and MIL-DTL-24308K and provided real-world examples from domain experts. I have also found pdfs for DIN 41652, CECC 75301-802 and referenced spec and marketing materials for Amphenol, Assmann, and Farnell/Newark and the only instances of a "standard" is when they list A-E sizes as an afterthought to aid people who are not following the actual standard to source standards-compliant parts (or ITT Cannon).
What is there, besides blog posts, to show that I am not correct?
edit: As a certified, triple-audited, ISO 9001-compliant weirdo, I am going to write up a nonconformity report, digitally sign it, print it out, manually sign it, then stamp it, then initial the stamp, then get it co-signed, stamped, and initialed, then scan it, then upload it into BMS, then print it out again, write the document control number on it, stamp and initial next to the document control number, have a second engineer stamp and initial it, and then hand it DIRECTLY to Quality if anyone ever refers to D-Sub connectors using non-standardized nomenclature ever again.
This is serious business and we are serious engineers here.
But language is for communication, and the most correct language is that which communicates best.
A conversation burdened with “well actually” tangents about one participant’s personal passion gets pretty tiresome.
I don't think shittalking "well actually" conversations in the context of an equipment vendor making a cutely-titled article that is very sympathetic to the inexact language around designators for products they offer is the play.
"Your service request will result in X hours of downtime, as well as ireversible data loss between T1 and T2, and a reset of your system back to the state it was in at T1. All changes and interactions after T1 will be lost. Is this what you expect and want?"
Beyond a certain amount of service disruption or monetary investment, asking twice and making sure is prudent, not pedantic.
Nothing saves money like a good well actually.
But things like DB9 and RJ45 are so commonly used that anyone taking them literally is either being obstinate or are completely new to the field.
This seems to be biased in US-American culture. In Germany, people are in my observation much more prone to analyze words and sentences (often by their origins), and many people wouldn't accept a "wrong" way to express things to be correct.
Just to give one example (which also works in English): "[die] Alternative" (the alternative): this word comes from Latin "alter, altera, alterum" (the other). This means, that there exists only one other. So educated people love to point out that talking of multiple "Alternativen" [alternatives] is wrong; by the word origin there can only exist one alternative (the other one). If more than one "alternatives" exist, so, to be precise, you likely want to use a different word.
Addendum: nevertheless: "alternate" is also derived fron "alter, altera, alterum" (the other one), so my point above still holds.
"The" often refers to a group or category.
"The other" is actually a phrase I would take to be incredibly inclusive in meaning if not followed by another specifier (it means "the category of everything that is not us").
"The alternative" is similarly a category structure. It's a singular category, made of many possible members, or alternatives.
You may still only pick a single alternate for each case, but that does not mean that a category of multiple possible alternative choices does not exist.
---
All that said, sparkfun is messing up by labeling this DE9. Spoken as someone who's done quite a bit of serial communication work. The defacto industry term is DB9, whether they like it or not, and most searching/purchasing will be done using that term. This is a "technically correct" fun article, with a name that would immediately mean I don't ever find this product (and would not purchase this product) unless they highlight that this is a DB9 breakout board with a bad name.
Simple test? Amazon has more than 4000 results for "db9 cable" and only ~110 results for "de9" cable. Even specialty sites like McMaster, which are usually pretty particular with their terms are happily calling this a db9 connector: https://www.mcmaster.com/products/connectors/computer-connec...
> "The" often refers to a group or category.
But this does not hold for the meaning of Latin "alter, altera, alterum" (the other one), from which the German and English word "Alternative"/"alternative" is derived.
Meanings have shifted since Roman times.
But that is a communication context, and there are other contexts where implications and assumed meanings are expected, and spelling everything out would be considered pompous, self-important, and ridiculous.
Perhaps not in Germany? But certainly elsewhere (but i believe that in German the pronoun "sie" can require assumed context to understand).
> Perhaps not in Germany? But certainly elsewhere (but i believe that in German the pronoun "sie" can require assumed context to understand).
I would indeed claim that in German such assumptions are often spelled out more explicitly than in English.
In casual language, sure, whatever.
For instance, the Amiga used 23-pin connectors to connect displays and disk drives. They had the same pin spacing as DB25 but were slightly smaller.
It is not like there is any real sensibility to the naming anyway. Of the common types, DA, DB, and DC seem to follow a pattern, but DD and DE then go completely off the rails.
Why couldn't a DB shell house a 9 pin connector? I don't see the physical contradiction (even if nobody actually manufactures such a thing).
They just don’t exist, and hopefully never will.
Originally? Because that was the naming convention that Cannon designated. Later, because the shell size wasn't sufficient to determine the number of pins.
> And how do you explain DE15 (popularized by VGA)?
Cannon's D-series connectors started with 2 rows, at the "normal density" of 326/3000 of an inch between pins. They later expanded the range of connectors with "high density" and "double density" connectors that put more pins at greater densities into the original shell sizes. DE15 is in the "high density" range.
They just don’t exist, and hopefully never will.
Maybe not as a standard, but I've seen a several companies stuff a crazy number of pins into a DE9 shell. I think one of them was my old GRiD Compass.
Beast of a machine. Heavy as hell, magnesium case, bubble memory, a screen that caused all televisions it was pointed at to lose their signal, and a sticker on the bottom saying it was illegal to use it in a whole list of countries, including Israel.
The funny thing about the GRiD DE9 connector is that it's labeled "Serial", but every DE9 serial port connector I've ever seen is 9-pin. I have to wonder what else they are cramming into that 20-pin DE9 "serial" port.
http://raster-burn.net/wordpress/wp-content/gallery/grid-113...
Footnote: keyed round connectors are not actually that bad, super strong, easy to seal and you can fit a large nut or bayonet clamp to them to make them extremely secure. However, this depends on having a well placed shell/key and mini-din doesn't, it is a bad connector. Not enough shell and key for solid locating so the pins tend to ride on the face while you try and orient it.
I think this was the one I had.
https://www.techpowerup.com/gpu-specs/all-in-wonder-9600.c86...
That being said, the DE-0 is real, but it can't hurt you.
That depends on several factors, like its current velocity.
Randall Munroe rules this space IMHO.
In retrospect, I think this may have been an adapter from DE9 to DB25, but it would have been a quick way to save a few pennies when only 9 pins were used for serial communication.
That is still pedantically different from a DB-25 of which we ripped out pins until it had only nine. The result would be "a DB-9" in big quotes, as it would't be "a", but more like "3/4 of a DB-25".
https://adamconn.com/product/8w8-connector
It's 8 pins, so, sorry, I'm not accepting it as DB9-of-doom. Maybe DB-8-of-doom.
No, it doesn't. All of the D-Subs are readily available in high density versions:
DA-15 | DA-26
DB-25 | DB-44
DC-37 | DC-62
DD-50 | DD-78
DE-9 | DE-15
There are also double density connectors putting 52 pins in a DB housing and whopping 100 connectors in the DD housing.
But: it was probably quite common on joystick interfaces, now you mention it. Thinking along those lines and searching for ‘twin joystick adapter’ let me actually find an example: https://www.ebay.com/itm/276075015721
Worth noting that in the image that shows two joysticks plugged in they really don’t look like they fit all that well…
composite video - RS-170 - monochrome video - EIA-170 - NTSC - black and white video - CVBS - B&W video - RS-170A - analog video - PAL - yellow RCA plug - just plain "video"
These don't even all refer to the same thing, and some are definitely more correct than others, but all are used even by technical people.
Here's another one: "Amphenol connector", "Cannon connector" or "Molex connector". It's the same as saying "Ford car".
The traditional diskette is 1440 KiB. I.e., base-2, today named "kibibyte" though in that day that word didn't exist yet & it was just a kilobyte and the base 2 inferred from context. Clearly, someone didn't infer, and moved the decimal, so that 1.44 "MB" is 1.44 * 1000 * 1024 bytes. The actual capacity is thus either 1.41 MiB or 1.47 MB.
also cal state irvine had a compsci prof who said "jigga-byte"
It's not like the situation with hard drives where they're going against industry convention for marketing purposes.
There were also other, weirder setups where you could get various other capacities. It was a wild time.
That is still what most people do. Only very pendantic individuals insist on using KiB, etc. Normal people are just fine inferring from context whether base-2 or base-10 is meant.
https://pub.smpte.org/doc/st170/20041130-pub/st0170-2004_sta...
I usually call those "headphone cables" just to be contrary.
No I haven’t and the same is true for approximately everyone else.
Because we have not been using D-sub connector terminology at all. We have been talking about the things that come with (and without) DB9 connectors. We have been (mostly) playing —- as the witty Wittgenstein would say — a different language game.
That’s why you know what I mean. So bring me a slab.
It's perfectly fine for a product manager to say "DB9", but the guy who has to order the part from a supplier will probably want to use the correct terminology. If there's a mistake, it's the supplier's fault.
> Words mean things.
But might question what your wiring has to do with a 2000s-era Aston Martin.
There are, of course, devices that use more than that, but most things seemed to use less. Maybe that's part of the reason the 9-pin became more standard.
ETA: Oh hey, just to make things confusing, Apple used DA-15 for video on older Macs.
https://chatgpt.com/share/6883b2ff-d26c-8002-bc4d-b184d7afd4...
The biggest problem with these standards is they are used for everything and so you cannot be sure that if the cable fits it will work. If a USB cable fits it will almost always work - but if it doesn't it will be obvious to your average idiot way (that is you can plug a mouse into a power supply - but nobody expects it will work). USB-C somewhat violates that, but even still it mostly is a case if you can get the connectors to fit it works.
RCA/phono jacks are from the 1930s - when record players and radios were first a thing.
But headphone jacks - originally phone switchboard jacks - are way older, dating to the 1870s.
When the plug is inserted, the jack "breaks its normal connection." Like they didn't want to leave the audio output like a floating pin to reduce stray voltage?
Scribner calls the switch "spring-jack" after "jack-knife" where the "jack" part of it comes from the name Jack and in the 1300s meant a mechanical device. So the "female" component of the connection was thereby given a "male" name.
Charles E. Scribner filed a patent in 1878 to facilitate switchboard
operation using his spring-jack switch. In it, a conductive lever pushed by a
spring is normally connected to one contact. But when a cable with a
conductive plug is inserted into a hole and makes contact with that lever,
the lever pivots and breaks its normal connection. The receptacle was called
a jack-knife because of its resemblance to a pocket clasp-knife. This is said
to be the origin of calling the receptacle a jack. Scribner filed a patent in
1880 which removes the lever and resembles the modern connector and made
improvements to switchboard design in subsequent patents filed in 1882.
late 14c., jakke "a mechanical device," from the masc. name Jack. The proper
name was used in Middle English for "any common fellow," and thereafter
extended to various appliances which do the work of common servants (1570s).
> In a telephone-exchange system the wires of the several subscribers are run into a cen tral office, where, upon request, any wire may be connected with that of any other subscriber.
> In Fig. 4 is shown the cut-out connected with subscriber's wire in and the relay and annunciator P and O, and also, with the operator's telephone J, by means of the plug A, which is provided with a metallic point, and conducting-cord d. The connections are formed as follows: The subscriber S, by throwing on his local battery, sends a current along the wire in through the relay P, which, closing, the annunciator number of S is indicated at O, and the current passes along the Wire H, and thence through the switch to the ground Wire G.
a) Frankenstein is the real monster in the book
b) The monster is Victor's son, so inherits the family name and thus is also (a) Frankenstein
c) A modern adaptation gives the reader explicit permission to use "Frankenstein" as the name for the monster: https://xkcd.com/1589/
“Look out, there’s a Frankenstein to push into that lake!”
But can never resist the Frankenstein’s monster pedantry, I find it hilarious.
Set input and output and check cost.
Without that it is barely worth the distinction.
* Decimated. How many of you know this means (or once meant) reduced by 1/10?
* Literally. Often used to mean figuratively, to the degree that it can be relied on to mean nothing at all.
* Reign, as in "reign him in". Clearly now an accepted misuse, reign once defined what a monarch does to a kingdom, not what a cowboy does to a horse (i.e. rein).
* Fewer / less. Sadly interchangeable in modern writing, "fewer" was once reserved for enumerable things, while "less" referred to continuous measures. Less water, fewer liters of water.
* Double precision. In computer science, defined in IEEE 754 as a floating-point data format with a 53-bit mantissa, therefore 15.95 decimal digits (53 * log(2)/log(10)). Now the norm, the default, to the degree that people may forget what "double" refers to. Because of double's ubiquity, in the fullness of time I expect single precision will come to be known as ... wait for it ... half precision.
See the online interactive adjuncts here: https://connectorbook.com
I grew up in the 70s-80s with serial connectors and a drawer full of cables, DB25-DB9 adaptors, gender-benders, null modems, breakout boxes, etc, and the only (very common) source of incompatibility that I can recall was connecting devices where one side wanted hardware handshaking but the other didn't provide it, so having to make custom cables with handshaking tied hi/lo to fake it.
Some devices used software XON/XOFF handshaking, so for example on a typical terminal, depending on what you were connected to, you could pause text being sent to the terminal with XOFF (Ctrl-Q), and resume with XON (Ctrl-S).
I've got a softspot for serial communications - used be more a source of fun rather than frustration to dip into the draw of cables/etc and get two devices happily talking to each other.
Handshaking yes, but not all potential RS232 signals, of which there are 11.
I work with RS232 frequently and even CTS/RTS is rare to use. Never personally seen anything use DTR, DCD, DSR, or RI though I know they did see historical use.
That is all. Everything else is blah blah blah (about DB9, love all the examples of other goofy identifiers!)
People strive for accuracy and remember things. I love people-in-general and they have an impressive track record. They improved on the standards committee.
I spent years wishing (and pretending) that this wasn't the case, but you can't fight the wind.
"Kettle lead" (Which is notched to indicate it can take a higher temperature and most of cables aren't that, they will be the c13 type), and their face lights up and a cable will be handed to me.
Just one of those things that's wrong, but it's not worth being pedantic over it, imo.
Ironically in Europe where the IEC cables were familiar from kettles, they've largely been superceded by cables hardwired into a base pad onto which the kettle is set.
dec0dedab0de•18h ago
cestith•17h ago
dragontamer•17h ago
DB9 or DE9 isn't even the end of it. There are lots of ways to run a serial line.
Findecanor•17h ago
That is quite common in the pro audio/video installation world, where RS-232 is common but needs extenders for longer distances.
Within A/V, the norm for local RS-232 lines is actually not DE9 but 3-pin terminal blocks! (RX/TX/GND) I've seen those even on Cisco video codecs, priced $10'000+.
dragontamer•17h ago
https://www.amazon.com/Console-Female-Serial-Ethernet-Rollov...
sokoloff•17h ago
Here's the cable they use: https://www.bhphotovideo.com/c/product/1263972-REG/comprehen...
mindslight•3h ago
numpad0•16h ago
mikestew•15h ago
Eh, depends on "proprietary", I guess. In the PLC world, using an RJ45 for a variety of serial uses is not uncommon. I've never touched a Cisco router in my life, but I've got a few things like these laying around:
https://www.networktechinc.com/serial-rj45-adapters.html
Arrowmaster•6h ago
The pinout is also called a Yost Cable. You can read about it on https://yost.com/computers/RJ45-serial/ but its an interesting solution to converting DTE and DCE sides to using a standard port and cable. The downside is that the DIY adapters online need some soldiering to bridge the ground wires and more.
I do believe the DTE and DCE pinouts on the yost page are swapped though. I recently tested the pinouts of a Cisco DE-9 to 8P8C (DB-9 to RJ45) with a multimeter and came up with the DCE pinout instead of the DTE one. I then built an adapter with the DCE pinout to connect to my servers serial port and use them as a make shift null modem cable for terminal access.
If I would have know more about this 5 years ago while still at a previous employer, there was some old equipment that used an unknown pinout that would have gotten a DB-9 to RJ45 adapter slapped on it to change it to Cisco/Yost pinout. I was told not to loose the serial cable in the rack with the device because it was the only one that worked on it but never investigated more into it to find out if it was a straight through, null modem, or something else entirely.
alnwlsn•17h ago
cestith•15h ago
icedchai•14h ago
I also remember some 90's terminal servers that had enormous "octopus" cables. There was a single connector on the box that broke out to 8 to 16-ish DB25 serial ports.
kps•12h ago
bwann•15h ago
raverbashing•12h ago
For a Parallel port, sure 25 wires is right there. But not for a serial port
kps•12h ago
II2II•12h ago
kps•11h ago
chillingeffect•9h ago
raverbashing•48m ago