It's a DE9, not a DB9 (but we know what you mean)
253 comments
·July 25, 2025dlcarrier
OhMeadhbh
Right. RJ45 was sort of like an 8P8C, but had a thing on the side so you actually couldn't plug a "real" RJ45 cable into a "normal" 8P8C slot.
benlivengood
And Molex power connectors are actually AMP Mate-n-Lok connectors.
I didn't learn this until this year...
dcrazy
Which “Molex connector” are you referring to? The ATX spec specifically specifies Molex Mini-Fit part numbers, and claims this is for compatibility with PCIe: https://cdn.instructables.com/ORIG/FS8/5ILB/GU59Z1AT/FS85ILB...
Is Mate-n-Lok perhaps a compatible product from a competitor?
numpad0
"Molex" usually refers to flat 4 pin AMP 1-480424-0 or Molex 8981-04P connectors(part number taken from random pdf on the Internet[1]). Confusing as it is... Actual Molex Mini-Fit are rarely colloquially referred to as Molex.
1: https://community.intel.com/cipcp26785/attachments/cipcp2678...
fredoralive
It’s the one the diagram of connectors calls “peripheral power connector” but the document doesn’t seem to go into details for it. Basically the original PC drive power connector, so 5.25” drives, older hard discs, optical drives etc. use it, in the latter cases it’s been replaced by the SATA power connector.
bradfa
ATX should call out Molex Mini-Fit Junior connectors. There are many Mini-Fit.
0_____0
A lot of connector series are are multi-sourced because big clients tend to require this. For example the 38999 series connectors used in military and aviation applications are made be TE, Amphenol, Souriau, ITT Cannon, Eaton...
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
anonymousiam
...and Berg (0.1") connectors are now Dupont, even though Dupont doesn't make them anymore, and has had nothing to do with them since 1993. Everyone called them "Berg" in 1978 when I was first exposed to them, even though Dupont had acquired the product line from Berg in 1972.
https://www.reddit.com/r/electronics/comments/ioc6sf/i_final...
brudgers
While your preferred specification is excellent, It’s “an ethernet port” in ordinary usage. Or “ethernet jack” in more technical contexts and entirely sufficient for Ali Express.
skissane
> While your preferred specification is excellent, It’s “an ethernet port” in ordinary usage. Or “ethernet jack” in more technical contexts and entirely sufficient for Ali Express.
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.
spauldo
That does you no good in my line of work, where it's just as likely to be a serial port.
noobermin
After googling for an image of that, jesus christ you learn something new everyday.
dontdoxxme
2.5GBASE-T? But I do 10GBASE-T over one. Provided it has Cat 6A cable inside it and has been tested to IEC 60512-9-3 & IEC 60512-99-002. (See https://ieee802.org/3/bt/public/oct15/Draft%20of%20IEC%20605... for some fun photos of what happens when PoE is disconnected on a connector before IEC 60512-99-002...).
timerol
The combination of "When documenting" and referencing "J3" indicates that dlcarrier is referencing a limitation of a specific port on a product that they worked on, not a set of global limitations on any 8P8C connectors
dlcarrier
I had assumed that the wires in the jack would rest along the bottoms of the blades in the plug, but I guess if it was never designed for high current applications, the contact area wouldn't be a consideration.
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.
DHowett
If you can turn the port off and then back on remotely, perhaps you can skip the unplugging part completely? I know that some managed PoE switches even offer a button to power cycle a port.
formerly_proven
You'll also enjoy annex H of https://usb.org/sites/default/files/USB%20Type-C%202.4%20Rel...
mayli
Yeah, I learned that rencently, engineers are dumb on naming things and remember the namings.
aruametello
_o/
100% guilty here, ouch.
also never saw a 8P8C "keyed, real rj45" connector in person.
bobmcnamara
Most 8P8C other connectors are incompatible with RJ45.
Why wouldn't you say RJ45?
wsh
RJ45S and RJ45M are ordering codes for so-called “registered jack” configurations for terminal connections to the U.S. telephone network. These codes were defined until 2000 in the FCC Rules (47 CFR § 68.502(e)) and later in the TIA/EIA-IS-968 standard, and they refer to single and multiple arrangements of two wires and a programming resistor on a miniature eight-position keyed jack.
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.
LukeShu
Specifically, what is colloquially an "RJ45" or "Ethernet" connector is an 8P8C "Bell System Miniature Plug/Jack" (AT&T's original name; it is a smaller version of the older Bell System connectors) / "miniature plug/jack" (FCC genericization of the name by removing "Bell System", even though the word "miniature" is no longer meaningful without context) / "modular jack" (ANSI/IEC genericization). That is what is meant when just "8P8C" is said.
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.
bigbuppo
RJ45 is a specific AT&T USOC order code to slap a normal 8P8C jack on someone's wall to provide something like multi-line analog telephone service.
arghwhat
RJ45 is a mechanically (slightly) different connector, but indeed all RJ specs were for phone lines, with RJ45 focused on several lines for high speed modem connections.
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. :/
LukeShu
RJ45 is a keyed 8-position jack, not a normal 8-position jack. ("Keyed" means that there's a notch in the side making it a different shape; you would not be able to fit an "Ethernet" connector into it.)
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.
Sammi
I used to do phone support for a phone company / isp and I have no idea what you just wrote.
pythonguython
Well you definitely SHOULD say RJ45. We do a lot of networking at my job and if I asked for an 8P8C connector, I would get confused stares. Say Ethernet cable, Cat 6 cable (or whatever cat), or RJ45. Sometimes being correct isn’t the right thing to do.
rblatz
If a contractor installed exactly what he asked for, an RJ45 jack which would be unusable for his needs he would have no grounds to stand on to demand it be corrected without paying more. By specifying the technically correct name as well as the colloquially recognized name he is being precise and accommodating.
zettabomb
D-sub has got to be one of the longest enduring connector standards I can think of, apart from wall outlets. They're from the 50s, originally for military use, and we're still speccing them in new space hardware today. Now they've got coax/twinax, high power, fiber, and even pneumatic "contacts" if you know where to look (and can afford it). I can't say that they'd be my first choice, personally, but it's quite remarkable to see how well they've fared over the better part of a century.
bluGill
XLR used (mostly) in audio is also from the 1950s.
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.
jameshart
DIN connectors also date from the 1950s, so do coax F connectors (the screw-coupled connectors for cable TV).
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.
noobermin
Are barrel connectors also as old as phono jacks?
adolph
The 1878 one is fascinating:
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.
https://en.wikipedia.org/wiki/Phone_connector_%28audio%29 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).
https://www.etymonline.com/word/JackGalanwe
Right, but the alternative of having 1 protocol per connector sounds awful as well, wouldn't you agree ?
zettabomb
Didn't even think of that, yes of course XLR and for that matter, 1/4" TS/TRS connectors were originally for switching phones at AT&T, before automated switching. Incidentally, you can also blow up quite a bit of stuff with them, depending on whether they are at consumer "line level", pro audio "line level", or even speaker level. We're definitely too comfortable with "if it fits, it works" (or at least isn't harmful".
jameshart
There was a wild period in early transistor electronics where DC power adapters sometimes used 1/8" phone jacks - before the barrel-style DC plugs became common. Having 9V DC in a form that could be plugged into a microphone input always seemed like a pretty insane choice.
jdietrich
European TVs still use an antenna connector that was introduced in 1922.
userbinator
The https://en.wikipedia.org/wiki/Edison_screw is from 1880.
paradox460
Phone jacks. Invented in the late 19th century. Still in use today.
EvanAnderson
I assume you're talking about these, right?
zettabomb
I assume you're referring to the 1/4" jacks, not RJ series?
Cyan488
Sparkfun should take it upon themselves to correct the centuries-old mix-up of "conventional current" next :)
stn8188
I always thought this was really interesting. The Coast Guard's Electrician's Mate training program taught electron-flow theory, so it was tough to switch my brain to hole-flow theory when I went to college. Technically the math is the same but man it threw me off with schematics.
DecentShoes
What's that?
Cyan488
Ben Franklin's coin flip landed the wrong way - nowadays electronics circuits are calculated and drawn assuming movement of positive charges, when in reality it's the negatively charged electrons that flow.
cperciva
Nothing wrong with saying that an absence of electron is moving. Both electrons and electron holes are just excitations in a quantum field anyway... ;-)
djaychela
For me, if I ever say IEC mains lead I get a blank expression. C13 even more so.
"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.
dingaling
Given the paucity of electric kettles in the USA, I wonder how that term became so widespread.
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.
indrora
British English, most likely.
9rx
> To be blunt, the term "DB9" is plainly inaccurate because it pairs the 25-pin "B" shell with a 9-pin count, a physical contradiction.
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).
bigbuppo
It can, but nobody would do that as it would be cheaper to use a DB-25 connector and not use all the pins. If they went for the cursed true DB-9 they would need to meet the minimum order quantity for a special order, pay for the manufacturer's tooling, and any required certifications. If you needed the spacing between pins for some reason you would probably just specify the use of crimp-and-insert.
That being said, the DE-0 is real, but it can't hurt you.
arghwhat
> That being said, the DE-0 is real, but it can't hurt you.
That depends on several factors, like its current velocity.
crtified
While your statement is perfectly accurate, I just wanted to blithely add that it's not the velocity that hurts you, it's the change in velocity :))
arjvik
Doesn't VGA use DE-15?
ianburrell
Edit: I was wrong, it is DE-15 connector. They squeeze 15 smaller pins into 9 pin housing.
jameshart
You can remove pins from D-sub connectors. There are dedicated tools made for doing so.
mmastrac
In a pinch, a pair of pliers works too.
jameshart
I have a vague memory of a computer (probably in the 16 bit era?) saving money on providing two joystick ports by using a DB25 housing with the middle pins removed, leaving two 9 pin clusters at the ends, into which two DE9 joysticks could be plugged. The case plastic covered over the middle of the connector.
spiritplumber
It was an accessory to let you use Amiga joysticks on the PC, from the mid 90s. I had one.
jameshart
Could well have been, though I’m still picturing a computer in my mind. Wasn’t the SAM Coupe, but that’s the sort of thing I’m recalling.
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…
mbreese
I’ve seen (many… many years ago) a DB housing with 9 connectors but with the spacing of 25 pins. Would this then be a DB25C9P?
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.
numpad0
Another possibility is Sun or SGI 13W3 display connector. They were DB25 shaped connectors with 10 regular pins and 3 giant pins for video signals.
mbreese
True. However, mine were for connecting to modems, so they were definitely only 9 pin serial cables. I didn't have the pleasure of seeing the 13W3 connectors until I was in grad school, and I still think they look weird. It didn't occur to me until today that they were the exact same size/shape as the DB connectors. They were so different that the thought never occurred to me!
II2II
How would you even count those 3 giant pins? If I recall correctly, they were for coax cables that ran within the main cable. So each of those pins would have a contact for the shield and the conductor.
bombcar
I’ve seen this also - I am unsure if it was a cost cutting measure or something else, but I’ve seen more than one connector with many missing pins.
II2II
The cables I saw were handmade. You can get connectors which are just the shield and an insulator with holes in the place of the pins. You crimp the pins onto the wires, then slide the pins into the insulator. You may have saved a few cents by not inserting the unconnected pins, but the reality is that most people left them out because there was no point in going to the trouble of putting them in.
kps
It was pretty common for RS232 (-ish) DB25 connectors not to populate unused pins.
javcasas
"DB" already means 25 pins, so well, it's quite hard to both have 25 and 9 pins at the same time.
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".
jcoby
> "DB" already means 25 pins, so well, it's quite hard to both have 25 and 9 pins at the same time.
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
The high density versions are commonly used in aerospace applications. Garmin is pretty fond of them.There are also double density connectors putting 52 pins in a DB housing and whopping 100 connectors in the DD housing.
rchard2scout
Also DE-15 is the standard connector used for VGA.
bluescrn
There’s also a now-quite-rare 23pin variant, which was used for the Amiga video port. Those connectors are getting harder to find these days, some people have resorted to modifying 25pin connectors when making Amiga video cables
ComputerGuru
DE-15 is none other than VGA.
SAI_Peregrinus
DB housing can fit 25 pins in 2 rows. But it can also fit 9 really honkin big pins in 1 row, with a custom mold & pins. 3x groups of 3x12-gauge pins for 60A 3-phase delta power connector in a DB sized shell would probably work for a while before you burn your house down.
javcasas
You mean this?
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.
relaxing
Sure you could do it. You could even put 25 pins in 9 pin housing if you made the pitch smaller.
They just don’t exist, and hopefully never will.
somat
Heh flashback, I had an ati all in wonder, which was a video card with built in video capture. Now this involves a lot of ports so the model I had used a port breakout dongle for the video capture stuff, and some engineer had the bright idea to run all these pins through a mini-din connector. Think a ps/2 connector with about 10 pins crammed into it. Now ps/2 connectors are sort of stupid in the first place. why a round connector that is keyed to only go in one way? But this 10 pin variant was a nightmare to insert and by about the third time I made a firm resolution to never unplug it again if I could help it.
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...
reaperducer
Sure you could do it. You could even put 25 pins in 9 pin housing if you made the pitch smaller.
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.
leptons
Seems like it has 19 pins in a DE9 shell. That's a lot. VGA connectors were also in a DE9 shell, but had 15 pins.
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...
9rx
What's the physical contradiction, then? I don't get it.
aleph_minus_one
The physical contradiction is that the standard requires a particular pitch of the pins, and a specific distance of the pins from the shell.
alnwlsn
There's a lot of things like this, especially when the connector is commonly used for just one thing. One is "composite video" which at one point or another I have heard items on this list used interchangeably (though not always at the same time):
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".
deathanatos
The 1.44 MB diskette is my canonical "dear God what happened"-named thing.
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.
hinkley
Hard drives continued to make that mistake, and once you got to GB size they were overselling the disk space by an appreciable amount.
alanfranz
hard drives intentionally use giga and tera rather than gibi and tebi. They're right; it's the memory sticks that are usually wrong :-)
bigstrat2003
> 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
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.
Arrowmaster
My opinion is use KiB as the abbreviation but pronounce it as kilobyte. It pisses off both sides but makes the most sense to me for both being technically and historically accurate at the same time.
fghorow
Back in the day -- when used for a disk drive -- we used to call 1000 * 1024 bytes a "marketing megabyte" and 1024*1024 bytes a "megabyte". YMMV.
bigbuppo
I thought they tossed the fool that tried to make mebibyte a thing off a bridge and we tried to forget about that.
yjftsjthsd-h
Perhaps the formatted capacity, or the safe capacity, but I can specifically recall being able to format those same floppies up to... I forget, maybe ~2MB? Something like that.
deathanatos
Yes, the typical formatted capacity. The word "traditional" was the brevity which was attempting to sum that up.
There were also other, weirder setups where you could get various other capacities. It was a wild time.
krs_
Same with older floppy disk formats. Using FAT16 (or FAT12 on some systems) you can often format DD 3.5" disks to 830K instead of the usual 720K. On the Amiga the same disks are usually 880K.
null
bigfishrunning
My favorite example of this is using "aux cable" to refer to an audio cable with a 3 or 4 pin 3.5mm connector on the end (because car stereos would have a 3.5mm jack labeled "Aux" for "Auxiliary input")
I usually call those "headphone cables" just to be contrary.
wsh
You forgot SMPTE 170M, which is probably the definitive standard at this point:
https://pub.smpte.org/doc/st170/20041130-pub/st0170-2004_sta...
brudgers
You have been misusing the D-sub connector terminology
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.
null
dec0dedab0de
I always just called it a serial port, because I could never remember DB9 to begin with. I really hope I remember this so I can impress some nerds in the future with how pedantic I can be. (I don't know how to write that last sentence without it sounding sarcastic, but I really meant it.)
cestith
Some other pedant might come along if you keep just calling it a serial port. They might mention that it’s specifically RS-232, and that DB-25 is also used for that. They might also mention that “serial port” could include ports for RS-422 and RS-485. They might even mention SIO and USB.
dragontamer
Aren't Cisco switches (and a large number of other switches) loaded with Serial Port / RS232 over RJ45?
DB9 or DE9 isn't even the end of it. There are lots of ways to run a serial line.
alnwlsn
Null modem, crossover, DTE, DCE, straight-through, full handshaking, no handshaking, RS-232 or TTL levels. Plus CAN, RS-485, RS-422, CGA video, RGB video, and any number of industrial things use or can use the same DE9 connector (including sometimes for power).
icedchai
DEC equipment had something similar. A 6 pin "MMJ" connector. It almost looks like RJ45 except the clip was off center.
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.
cestith
I haven’t touched Cisco gear in years, but that at least was true for a long time.
Findecanor
Are you sure those weren't using RS-232 over TCP/IP over Ethernet?
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+.
raverbashing
The thing I don't get about this is why did people think it was a good idea to have a serial connection over DB-25? You honestly need only 3 wires. Not 25
For a Parallel port, sure 25 wires is right there. But not for a serial port
kps
CTS, DCD, DSR, DTR, GND, PG, RI, RTR, RTS, RxD, TxD (alphabetically) makes around 11, I think.
bwann
and V.35 and X.21!
1970-01-01
My VGA (DE-15) and keyboard and mouse (Mini DIN #6) ports disagree. The printer port (DB-25) could not be reached for comment, as it is still set for uni-directional.
noobermin
One of the more confusing versions of this I came in contact with recently is the 23 pin amiga rgb port. It has no real official D-subminature name as there is no such designation for the shell of a 12+11 pin port, which I assume is due to the fact that it was for a non-IBM machine...BUT some sellers (on aliexpress) DO call it a DB-23 port...I did figure it out eventually and got a few but it did take a while after searching for "12+11 serial" and being a bit frustrated at not finding anything.
shermantanktop
This is like King Canute and the tide. Technical pedantry is often interesting, as this is, and can lead to deeper understanding, though this doesn’t.
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.
dogleash
Being on the sharp edge of professional "do you want what you're asking for, or what I assume you want?" misunderstandings, you learn that it breaks in both directions often enough that sometimes not being pedantic up front isn't an option.
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.
spauldo
Normally I agree. The only time I ever raised my voice at a subordinate was because they were consistently lax and inaccurate with technical details. Things like mixing up C and C++ in conversations where it mattered.
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.
tetha
This is why I've learned to present people with the concrete consequences and results of their service request. Especially if I get the feeling that someone does not comprehend what they are asking for.
"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.
Affric
Gotta love that sharp edge.
Nothing saves money like a good well actually.
xp84
In this case, is it that helpful? Since only a lunatic would want a true DB9 and no one’s ever made a giant connector with 9 pins, I fail to see the importance.
aleph_minus_one
> But language is for communication, and the most correct language is that which communicates best.
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.
horsawlarway
I think this implies a meaning of "the" that doesn't actually exist in modern english.
"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.
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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...
aleph_minus_one
> I think this implies a meaning of "the" that doesn't actually exist in modern english.
> "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.
UncleSlacky
"(The/an) alternate" is probably the ahem _alternative_ term you're looking for...
aleph_minus_one
I am not a native English speaker, so I honestly was not aware of this English word.
Addendum: nevertheless: "alternate" is also derived fron "alter, altera, alterum" (the other one), so my point above still holds.
shermantanktop
I think you're proving my point. If the people I am talking to and the language I am using both demand precision in word choice, then I would be foolish to use the wrong term and then say "well, you should have known what I meant."
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).
aleph_minus_one
> 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).
I would indeed claim that in German such assumptions are often spelled out more explicitly than in English.
csours
It depends on context. If you're working from a document that is otherwise correct, and you come across a mistake like this, it's worth checking.
In casual language, sure, whatever.
gchadwick
I do wonder why they decided to have have separate shell size and pin designations given there appears to be a 1:1 correlation between shell sizes and pins (i.e. the 'B' shell is always 25 pins, the 'E' shell is always 9 pins). Perhaps there was plan to have fewer pins in the same shell at some point?
jones89176
it's not always 9 pins. you can get pretty creative regarding the number and type of pins (high current, coax) you can fit in that shell:
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-...
geraldcombs
There's also 13-W3: DB shell, 13 pins, 3 of them coax: https://en.wikipedia.org/wiki/DB13W3. They were used for high-end workstation video back in the day.
donaldihunter
I came here to share this cursed connector. I remember it well from Sun workstations
bunnie
VGA connectors used the same shell as the DE-9 but had three rows for a total of 15 pins.
gchadwick
An excellent example I really should have been able to think of myself!
gjsman-1000
And for reasons I don't fully understand, somewhat unrelated - if you look around almost any small business in my area, it's almost always VGA, rarely DVI, almost never HDMI or DisplayPort.
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.
cestith
Confusingly enough, I’ve actually seen real, properly named DB-9 connectors. They were a cheaper version of a DB-25 to DE-9 converter. Instead of combining the extra pins properly, they just had a DE-9 on one end connected to only 9 pins on the DB end. They sometimes occasionally even worked properly at low enough line rates.
elsjaako
DE15 and DA15 both exist and are pretty commonly used, I'm not aware of any other conflicts in normal versions.
However, you can get weird Dsub connectors with things like COAX in there, so having the shell sizes have names can be useful.
dfox
Coax and high-current/voltage pins are not that weird. You can also get truly weird semi-proprietary pins like fiber optics or even pneumatics/fluidics.
dec0dedab0de
I vaguely remember there being some proprietary connectors that were the same as the standard with a single pin missing.
dfox
IBM did that pretty often. And well, the original VGA connector had pin 9 missing and used as a key.
null
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sjsdaiuasgdia
IMO, the issue is less that there is a shell designation and more that the shell designation is hard to interpret.
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.
Also, it's 8P8C, not RJ45, and sometimes it's more important to use the term from a standard body, but usually it's more important to use the term everyone knows. When documenting, I recommend saying something like this: