Why does this sort of thing bother you?
Why do you feel it's so important to insist that the
term 'null-modem' is only valid if the modems it replaces are both
RS-232 and not if one of them is a USB modem? A modem is a modem
(although technically the box that connects your computer to the
internet may /not/ be a modem, something else for you to rant about ;-) )
I certainly had much better results googling for "USB serial null
modem" than "USB Provides a DB25M wired as DCE"...
If Tripp-Lite calls their U209-18N-NULL cable a "USB to Null Modem
Serial FTDI Adapter Cable" (and most people who've never heard of DTE
or DCE know what that is) then I'd say that there /is/ such a thing,
despite the fact that you "know better" and don't want to use the term.
https://www.tripplite.com/usb-null-modem-serial-ftdi-adapter-cable-com-retention-usb-a-db9-m-f-18in~U20918NNULL
IMO you should have put it all under "opinion".
Or are you really just trolling?
----- Original Message -----
From: "Brian K. White" <[email protected] <mailto:[email protected]>>
To: <[email protected] <mailto:[email protected]>>
Sent: Friday, May 31, 2019 2:19 PM
Subject: Re: [M100] possibly ideal serial cable?
> It's no great mystery that web sites, who wish to sell things,
employ as
> many keywords as possible so that even uneducated people who search for
> things by the wrong terms can still find them and buy them.
>
> That doesn't make the term any less incorrect, nor does it mean anyone
> else, in any other context (meaning me, and here), should use the wrong
> terms for things if they know better and don't want to.
> --
> bkw
>
> On 5/31/19 1:51 PM, Mike Stein wrote:
>>
>> For something that "there's no such thing as", there sure are a lot of
>> various null-modem adapters and cables out there.
>> BTW, while we're picking nits, USB/is/ a serial protocol, so a
>> USB<>RS-232 adapter /does/ have two serial ports!
>> As the name suggests, a null-modem cable/adapter/whatever /replaces
>> a serial modem-to-modem/ connection between two computers regardless
>> of the protocol used; RS-232 and RS-232 modems have been obsolete for
>> decades, so the term 'crossover' has become more popular, but it's the
>> same thing: a cable or adapter to directly connect two computers
together.
>> A pair of modems would connect the transmit signal (pin 2 on an M100)
>> on one end to the receive pin (pin 3) on the other end. When you
>> replace those 2 modems (RS-232, USB, whatever) with a null-modem cable
>> you emulate those modems and do the same thing, connect transmit to
>> receive etc. (instead of straight-through, connecting transmit to
>> transmit etc.)
>> Good luck in your quest to eliminate the term "null modem" in
>> reference to USB cables; I suspect it'll be around for a while and
>> more easily understood by many folks than "Provides a DB25M wired
as DCE"
>> FWIW, here's a USB-RS-232 Null modem cable; better send them an email
>> to let them know that "there's no such thing" ;-) :
>>
https://www.startech.com/ca/Cards-Adapters/Serial-Cards-Adapters/USB-to-Null-Modem-RS232-DB9-Serial-Adapter-Cable-DCE-FTDI~ICUSB232FTN
>> Here's an example of a USB-USB null-modem RS-232 replacement; DTE and
>> DCE have no meaning here whatsoever.
>>
https://www.ftdichip.com/Support/Documents/DataSheets/Cables/DS_USBNMC.pdf
>> And here's an Ethernet null-modem (crossover) cable:
>> http://www.nullmodem.com/10BaseT-Crossover.htm
>> m
>> ---- Original Message -----
>>
>> *From:* Brian White <mailto:[email protected]>
>> *To:* [email protected]
<mailto:[email protected]><mailto:[email protected]>
>> *Sent:* Friday, May 31, 2019 5:56 AM
>> *Subject:* Re: [M100] possibly ideal serial cable?
>>
>> Technicality:
>>
>> There's really no such thing as null-modem in a usb adapter.
>> Null-modem vs straight through describes the wiring between two
>> serial ports. A usb adapter only has one serial port.
>>
>> That single serial port can be wired to be either a DCE port or a
>> DTE port. Most computers or host devices (like terminals) have DTE
>> ports, and most peripherals (like modems) have DCE ports, so that
>> a modem can connect to a terminal with a simple straight-through
>> cable.
>>
>> Most usb adapters are meant to drop in place of the serial ports
>> that computers no longer have, and so they provide a DTE port.
>>
>> A custom non-standard one could provide a DCE port instead, and
>> could be made even more non-standard by having a DCE port with a
>> female connector.
>>
>> So, it's not null-modem, but it is "Provides a DB25M wired as DCE"
>>
>> ------
>>
>> Opinion:
>>
>> I personally wouldn't like to combine the serial cable and the usb
>> adapter in one, especially not if the serial port will be so
>> unusual. I don't like uneccessary adapters and connection points,
>> but I do like standard interfaces. So there is a tug of war or a
>> balance between those two aims. I like the usb part to be
>> generically useful on it's own with anything else, and if the usb
>> part breaks, you can swap in any other standard usb adapter. Same
>> for the serial cable. It doesn't have a chip that could go poof,
>> but a wire or a pin could just break. If it's a standard cable, it
>> can be replaced with any other standard cable.
>>
>> I also don't like adapters hanging off of device ports directly.
>> I'd rather have the rigid plug that sticks out of a usb port or a
>> serial port be as small as possible. Aside from being generally
>> less annoying, it puts the least mechanical strain on the port,
>> and reduces the chance that you'll break the usb or serial port in
>> your laptop or other device. So if I have to use adapters, I try
>> to use a standard cable on each device, and stick any adapters in
>> cabling in the middle. Although, those mini adapters that are just
>> like two plugs back to back, a single one of those on an existing
>> plug isn't *too* bad.
>>
>> I also don't like relying on things that are too custom that you
>> couldn't find from other sources or 15 years later.
>>
>> But I myself spent some time hunting down the ususual "ideal"
>> serial cables to document on tandy.wiwk, so that you could have a
>> serial cable that had everything but the usb all in a single cable
>> with no adapters. Partly for the neatness and convenience, and
>> also to document something that a new user could buy and it "just
>> works" even if they have no idea how rs232 works. Those cables are
>> off-the shelf, not made custom by a single person, but they are
>> still non-standard cables that are really only good for this
one job.
>>
>> So, I'm guilty of violating that "standard interfaces" rule a
>> little myself, because those cables look like modem cables but
>> they're not. The really ideal minimal as possible arrangement, yet
>> that maintains all standard parts and interfaces all the way, is a
>> standard 9-25 modem cable, a standard usb adapter, and a 9m/9f
>> mini null-modem adapter in the middle. (Except I think no one
>> makes one of those mini-null modems with complete wiring, while
>> some of the cables I found are more complete.)
>>
>> I have to admit, for the purposes of simplicity and removing all
>> the variables that people are mystified by... this does remove all
>> opportunities to get anything wrong, and makes the smallest and
>> simplest object to include in a laptop bag along with the M100. It
>> only does one thing, but if you're only doing this one thing, this
>> is the simplest way to do it.
>>
>> I would put a label right on the plug that says For Model 100
>> though if I got one. Or at least one that says Port is DCE or
>> something.
>>
>> It's bad to have objects lying around that look like one thing,
>> but are actually something else. If I didn't know the extremely
>> bizarre special purpose this object was wired for (let's say I'm a
>> young relative 10 years from now) and I came across it in a box of
>> junk, and tried to use it, it wouldn't work, I'd watse time
>> spinning my wheels trying things that *should* work, and then
>> throw the thing away. Or I'd stumble upon some combination of
>> adapters that worked, and then I'd think I leaned how serial ports
>> worked except what I learned wouldn't work anywhere else. (and
>> then if I somehow ever found out out that it wasn't broken, it was
>> just wired up in an insane way, I would curse whoever made it, and
>> whoever didn't put big explanatory labels all over it).
>>
>> All that said, it's a cool find and I'll probably get one!
>>
>> For an example of what I mean about not combining too much...
>>
>> Say you don't buy into any of that nonsense I just bloviated so
>> much about, and you like this all-in-one cable because, duh, look
>> how slick that is! Right from the laptop to the m100 in one shot!
>>
>> Now you want to use mComm on your phone instead Laddie on your
laptop.
>>
>> Now what? You need... an adapter. You need an "otg" usb adapter to
>> go from the phones usb-c or micro-usb to provide a usb-a port. Do
>> you really want to go back to that guy on ebay and have him make
>> another special cable with a micro-usb on the end instead of
>> usb-a? If not, why not? What was the point of getting this custom
>> cable in the first place?
>>
>> And then next year when you get a new laptop that only has usb-c
>> ports. You need an adapter again, or you need yet another custom
>> cable whose only difference is a usb-c plug on the end...
>>
>> Maybe I won't get one after all because both those last two
>> examples are already true for me. I have an android phone and an
>> android tablet with only a micro-usb. My next phone will probably
>> have usb-c. I already have old and new laptops with both usb-a and
>> usb-c, including one with only a single usb-c port.
>>
>> --
>> bkw
>>
>> On Thu, May 30, 2019, 4:38 PM Jim Anderson <[email protected]
<mailto:[email protected]>
>> <mailto:[email protected]>> wrote:
>>
>> I ran across this eBay seller while looking for ham radio
>> programming cables for my various radios - the seller is a ham
>> and makes custom serial programming cables for hundreds of
>> varieties of radios. I did not think to look deeply at his
>> inventory when placing my order with him, but it occurred to
>> me today that he might also make different varieties of
>> regular DB-9 and DB-25 based USB serial cables, and what do
>> you know, he does!
>>
>> One of the cables seems like it might be perfect for our hobby
>> - USB with an FTDI chip on one end, DB-25 male wired null with
>> full handshaking on the other end, and what seems to be a
>> fairly thin and flexible cable in between. The only downsides
>> are that it's a bit pricey ($37 US) and that the DB-25
>> connector shell he uses may be too bulky to properly fit a
>> Model 100 without cutting extra clearance on the connector
>> shell or the M100 housing (this is a known problem with some
>> cables and the 100, but doesn't affect the 102 or 200). Also
>> AFAIK he only sells on eBay, not through other retailers,
>> which may be a problem for some people.
>>
>>
https://www.ebay.com/itm/FTDI-USB-DB-25-Male-Serial-RS-232C-Null-Modem-Full-Han
>> dshake-Cable-NM-25M/151495441948
>>
<https://www.ebay.com/itm/FTDI-USB-DB-25-Male-Serial-RS-232C-Null-Modem-Full-Handshake-Cable-NM-25M/151495441948>
>>
>> http://tinyurl.com/y3wln2l3
>>
>> I really wish I'd bought one while I was ordering cables from
>> him, even just to try it out (it would have been cheaper
>> because shipping to Canada is $$$ and I was getting three
>> cables sent already for the shipping price of one). If I have
>> a reason to buy anything else from this guy I'll definitely
>> get one of these and give it a whirl if nobody else has tried
>> and vetoed it by then.
>>
>>
>>
>>
>>
>>
>>
>> jim
>>
>
