What's wrong with Serial

[Don Wilhelm-3]

Folks,

This revalation about the RJ-45 jack being used and defined for use as an
RS-232 connector amplifies my point.  It is not reasonable to expect that
every RJ-45 jack is an RS-232 connector.  We know that they are used for
Ethernet connectors, Yaesu uses them for microphone connectors, they are
ofter used in telephone systems, etc. - so just by looking at the jack, it
is not possible to identify its use and pinout.

Similarly, the DE9 connector on a piece of equipment does not provide any
assurance that it is a serial port, let alone one conforming to the RS-232
standard.  Again, the K2 DE-9 connector is clearly labeled "AUX I/O".

73,
Don W3FPR


> -----Original Message-----
>
> The latest copy of the spec I had was EIA-232-F.  It did not
> specify the 8 pin modular connector.  EIA-561 covers the 8
> position modular plug when using it in an EIA-232 compatible
> system.  RJ-45 (Registered Jack) is defined in FCC part 68 and is
> a whole other ball of wax!
>
>

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[Mike S-8]

At 12:43 PM 6/21/2006, Jack Brindle wrote...

>The current evolution of the RS-232 spec also now contains a pinout  
>for an RJ-45 8-pin modular connector. ... RJ-45s allow much high panel density that DE9  
>connectors, even though they have the problem of being the same as  
>those used for ethernet connections.

The current RS-232 spec, TIA-232-F-1977, only specifies the traditional DB-25 and an alternate 26 pin connector.

The ANSI-TIA-EIA-723-1998 specification, which is more applicable to modern serial ports (RS-232-F only goes to 20 Kbps, "723" goes to 512 Kbps), adds the DE-9 connector.

Use of the 8 pin modular (RJ45 should not be hyphenated and refers to more than just the connector) is not defined in either spec. It is covered in EIA-561.

To the original concern, Elecraft chose a commonly available, easily used, reliable connector. It's not labelled "RS-232" or anything which would (should) lead someone to believe it's directly compatible. It's well documented. No problem.

BTW, an RJ45 doesn't actually exist, there are RJ45S and RJ45M telco interfaces. "RJ45" is an informal term incorrectly used to refer to 8 pin modular connectors.

All of this may seem a bit pedantic to those used to informal use of these designations, but in the standards world, correctness counts. It is through ignorance of the subtleties that incompatibility problems arise. Informal terms are fine, as long as everyone agrees. The problem quickly arises however, that not everyone does agree and being informal there is no authoritative reference to settle disputes. (from someone who's employer is a member/subscriber to most, if not all, communications/electronics standards organizations, and runs into this stuff regularly in real life situations)
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[Bill Coleman-2]

On Jun 21, 2006, at 12:49 PM, Jack Brindle wrote:

> Mini-Dins are simply not reliable. The connectors break all-too  
> easily, mostly due to the pins bending if the connectors are not  
> aligned just right. We intentionally moved away from them at Apple  
> because of this problem.

And here I thought that it was because USB was a better solution....  
At least, that's what they told me at WWDC 1997. Instead, it was the  
stupid connectors for Serial and ADB.

> There really isn't a good connector solution at present. If you  
> look at what is available in a semi-rugged form factor, we are  
> limited to D-shells, DINs (not mini-Dins), RJs, and not much else.  
> The RJs are not shielded, so we end up duplicating connectors out  
> of necessity.

USB connectors are highly reliable, sheilded, and you could put two  
of them in the space that a single DB-9 fits....

> I think Wayne made a good choice with the connector, and it is up  
> to us to realize that it is not standard RS-232 and just deal with  
> it. Of course, few, if any, other ham rigs have "standard" RS-232  
> connectors on their rear apron...

Indeed.

Bill Coleman, AA4LR, PP-ASEL        Mail: [hidden email]
Quote: "Not within a thousand years will man ever fly!"
             -- Wilbur Wright, 1901

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