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.)
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?
I use both DA-15 and DE-15 all the time in my line of work, and I am fastidious about using the correct terminology on all my drawings. Manufacturers are ironically some of the worst at getting this right.
The correct technical designation for a D-sub connector with nine pins is DE9.
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.
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.
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:
J3 is an 8P8C jack (commonly RJ45) for IEEE P802.3bz 2.5GBASE-T communications, backward compatible with Gigabit and Fast Ethernet
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.
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".
Not connector related, but I can't tell you how many people use time zones like PST year-round. The ST stands for "standard time," meaning not Daylight Saving Time. Right now, PDT would be appropriate.
The thing that kills me is that they could just say "PT" or "Pacific time" and be right, with less effort.
I always know what they mean, but it's wrong for more than half the year.
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.
If you keep calling it DB9 everybody knows what you're talking about. They don't think you're weird and they also don't waste time talking about terminology.
And this reminds me of the time that my colleague put DB15 on a whole bunch of drawings, and we ended up with DA15 connectors instead of DE15. If I see DB9 on any drawing that comes across my desk, it will be corrected.
We used the DD-50 connectors in the telephony world and called them "DD-50 connectors." I always wondered why they were "DD-50" and the 9 and 25 pin connectors were "DB-9" and "DB-25". Now I know... we were just using the nomenclature wrong.
Could the name "DB9" have come from 25-pin serial ports with only the minimum 9 pins populated? That would be a correct "DB9" and would also be valid electrically. I think I've even seen one of those in the wild before.
Given that DB9 is so pervasive (and I admit this is new information to me), I thought AI training data might include the error but no, ChatGPT knows DB9 is wrong:
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.
I hypothesize that the car cigarette lighter port is the only truly standard, widely-used connector remaining. Wall outlets, just for 120V in the US, have at least three variants. 3.5mm audio plugs have at least four variants.
53 comments
[ 3.0 ms ] story [ 96.2 ms ] threadIt’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.
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.
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.
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).
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 thing that kills me is that they could just say "PT" or "Pacific time" and be right, with less effort.
I always know what they mean, but it's wrong for more than half the year.
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.
https://chatgpt.com/share/6883b2ff-d26c-8002-bc4d-b184d7afd4...
I have soldered a lot of these into cable assemblies for automated welding fixtures. They are also found on some servo motors and cables.
Set input and output and check cost.