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Searching with Google returned only 3rd party documents (i.e. from chip vendors or university lectures). Is there a main document of such specification, similar to USB?

Amumu
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  • I think it's [this (OCLC WorldCat link)](https://www.worldcat.org/title/interface-between-data-terminal-equipment-and-data-communication-equipment-employing-serial-binary-data-interchange/oclc/38637094). Will look for a non-print reference. – uint128_t Jun 23 '16 at 15:20
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    Yes, but it is not free. And you might be disappointed that it only mentions connectors, pin names, and voltages, NOT the data format that is used. – Wouter van Ooijen Jun 23 '16 at 15:21
  • Have you tried to google "rs-232 standard"? It is giving you it's official name right away... But the document itself is not free. – Eugene Sh. Jun 23 '16 at 15:21
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    Wow.. that's a big score for such a question... – Eugene Sh. Jun 23 '16 at 17:40
  • @EugeneSh. Actually, I fully [agree](http://electronics.stackexchange.com/questions/240747/simulation-model-for-floating-gate#comment526623_240758). Well, of course I'm happy to get some rep but there are other answers I made that were more interesting. That could almost deserve a discussion on meta but I think there's actually nothing to do. – dim Jun 23 '16 at 18:17
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    @dim Well, in this case I am not even speaking of the answer, which did require from you some effort. I am speaking about the question, not demonstrating any and not very useful at all.. – Eugene Sh. Jun 23 '16 at 18:20
  • @WoutervanOoijen Nor does it actually define the functionality of the various signals. It was the development and popular adoption of the IBM PC that effectively "standardized" RS-232 pins and functions, to the point that you didn't need someone to build a custom cable, and you didn't need to own a breakout box to do it. (I still remember my mother going through major pain with a serial printer, because the vendor used an UNDEFINED pin on the 25-pin connector for a critical handshaking line, and NONE of the local "experts" in Austin knew about it.) – John R. Strohm Jun 23 '16 at 22:27
  • @EugeneSh. I tried google "rs-232 standard" and other terms but it did not show the official homepage. Hence, I asked this question. I guess many other people were in the same situation then. – Amumu Jun 24 '16 at 01:21
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    @Amumu: Are you serious? The second link for me is the Wikipedia article about rs232, which in the first paragraph states: *The current version of the standard is TIA-232-F Interface Between Data Terminal Equipment and Data Circuit-Terminating Equipment Employing Serial Binary Data Interchange, issued in 1997.* – Eugene Sh. Jun 24 '16 at 01:25
  • @EugeneSh. Google does not even provide the direct link to the homepage of such spec. And since I was trying to search for a link, I did not look at the Wiki article, and even if I did read, you might not assume that the organization published it online. – Amumu Jun 24 '16 at 01:36
  • @John R. Strohm Correct, that's why I mentioned only 'pin *names*'. But in these days of 3-wire connections, maybe with a DTR/CTS (mis) used to reset a target and force it into bootmode the functions of the 'other' pins (as far as they were ever used for a specific function) is nearly irrelevant. – Wouter van Ooijen Jun 24 '16 at 06:16

1 Answers1

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The original standard has been written by the Telecommunication Industry Association (TIA). Its name is EIA/TIA-232.

But you must pay to get it. You can buy it on TIA's store. This is the reason why you don't find it on the internet: publishing it is illegal.

Anyway, all the necessary information required to implement an RS-232 device is easily available on the internet and on various 3rd party publications, as you noticed. I guess TIA doesn't make much money from this standard anymore.

(and at this price, I wouldn't buy it)

Here are some useful resources:

  • Linear Tech RS232 Quick Guide, summing up pretty much everything needed from a technical point of view, in a single page.
  • Wikipedia page for more detailed explanations and some historical background.
  • An old app note from Dallas (now Maxim) covering all technical aspects in details.
dim
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    Wow, a big price tag for such a common standard. I guess the book has nice colors in it. – Amumu Jun 23 '16 at 16:07
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    @amumu Colors? For this price people should get an authentic [illmuninated manuscript](https://en.wikipedia.org/wiki/Illuminated_manuscript). – dim Jun 23 '16 at 16:30
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    @Amumu: Different licensing schemes. The USB spec can easily be found online but manufacturers must pay to buy a vendor ID so that device drivers can identify the device. Also, vendors need to pay an annual fee if they want to declare that their device is USB and use the logo (which is why some generic products form China do not say they're USB even though the connector is obviously USB). RS232 on the other hand has no licensing fee for implementations but make their money from selling the spec (this is the same business model as the PCI bus) – slebetman Jun 23 '16 at 18:22
  • Seeing how old serial port is, it still needs a person to pay to get the official specification??? I am surprised. – quantum231 Jun 23 '16 at 22:46
  • The RS-232 protocols are old, made for QAM transmissions,etc. I see many RS-232 to RS-485 adaptors and even I2C adaptors. Intel has stated that the DB-9 connector will be around for some time on work-stations and desk-tops, but if you write your own code or use LabViews basic drivers, the protocol is what you want it to be. For valid operation RTS and CTS should be used properly. –  Jun 24 '16 at 06:24
  • @quantum231 Just because it's old doesn't mean it's obsolete. RS-232 is a very reliable protocol, and the age means that there are countless software libraries and hardware devices available to facilitate it. I use it almost daily, including on new devices, not just legacy. – skrrgwasme Jun 24 '16 at 09:04