[GreenKeys] Interface ASR33 to Linux serial port

Tue Jan 9 12:08:44 EST 2024

Hi GreenKeyers,

In the past for my RS-232 projects when I’ve needed serial communications,
I ran into unexplained problems with USB-to-RS232-Serial converters
incorporating the Prolific chipset. Since Prolific has become so, well,
prolific, it has a huge market share, so foreign companies have knocked off
the Prolific chip and flooded the market with counterfeit chips marked
Prolific, but are NOT Prolific brand.  These counterfeit chips have flooded
the electronics parts supply chain, and therefore, have been inadvertently
used in even legitimate companies' USB adapters (even name-brand
companies).  To protect themselves, Prolific finally changed their drivers
so that their drivers are on the lookout for bogus chips. I think those
Prolific drivers are part of the Microsoft Plug-n-Play devices.  If the new
Windows driver finds a counterfeit chip being used on the system, the
driver will give a warning and disable the device by overwriting the driver
on your system. With the RPi running its version of Linux, I’ve scratched
my head trying to get gettys to run right because it might show the login
prompt, but either not accept characters, or it accepts characters but
would not give me a Password prompt, so I couldn't get logged in. Searching
on the internet, I saw other people had problems with the Linux drivers too.

So I’ve given up on Prolific and only use devices which use the FTDI
chipset. If a device doesn't specifically say it uses the FTDI chipset,
chances are it doesn't, so I don’t bother with it.

Recently I’ve had great luck with Gearmo 4-Port RS232 to USB FTDI chip
Adapter w/RX and TX Status LEDs (
https://www.amazon.com/Gearmo-Port-RS232-Adapter-Status/dp/B08P24ZQ1B
$44). It comes in a version that doesn't have the status LEDs for a few
dollars cheaper, but LEDs are well-worth it when trying to debug something.

If you only need one RS-232 port, I can recommend Gearmo's USB to Serial
RS-232 Adapter with LED Indicators FTDI Chipset (
https://www.amazon.com/gp/product/B00AHYJWWG   $23).

The only thing I can't verify is if it goes down to 110 baud (I don't have
a 110-baud device in the same location).  I did connect Ports 1 & 2
together (via a null modem connector) and opened two putty sessions set for
110 baud, 8 bits, 1 stop, no parity, xon/xoff, and it seemed to work (I
could send characters back and forth between windows).  I used putty
version 0.78 on Windows 11 and a command line of: "C:\Chuck> putty -serial
COM5 -sercfg 110,8,1,n,X" because I could never correctly configure putty
with its GUI.  However, when I opened a putty session for 300 baud and kept
the other at 110, I expected I couldn’t communicate between them, but lo
and behold, it worked anyway, so I’m not sure it actually went down to 110
and 300 baud.  Maybe it defaults to a certain speed if someone tries to
give it a speed it can't handle.  Like I said, I don’t have a 110 baud
terminal in the same location so I couldn’t really verify 110 or 300 baud
operation, but sometime I will and report back.

Hope the above helps.

Chuck
W9CFR

On Mon, Jan 8, 2024 at 2:36 PM Tom Lake <tlake at twcny.rr.com> wrote:

> I have a PiDP-11 as well and the Teletype works fine with it. I replace
> the PiDP-11 with the Pi 5 using the same RS-232 converter and I can’t log
> into Linux with the Teletype.
>
>
>
> *From:* Michael Katzmann <vk2bea at gmail.com>
> *Sent:* Thursday, January 4, 2024 5:33 PM
> *To:* tlake at twcny.rr.com
> *Cc:* greenkeys at mailman.qth.net
> *Subject:* Re: [GreenKeys] Interface ASR33 to Linux serial port
>
>
>
> I've got a PiDP11 with a 33 attached.
>
> Usually the 33 is driven off the PDP11/70 SIMH emulator.
>
> I tried running the agetty command as you showed and it looks like it
> worked (except bash is confused for some reason)
>
> The OS is Raspbian (32 bit) but its pretty close to Ubuntu (both based on
> Debian). I favour Fedora myself!
>
>
>
> Michael
>
>
>
>
>
>
>
> On Thu, Jan 4, 2024 at 3:52 PM Tom Lake <tlake at twcny.rr.com> wrote:
>
> I have an Ubuntu 23.10 system with agetty running on its eight serial
> ports. I can hook up most terminals to the ports and login to a bash shell.
>
> When I try to use a Teletype ASR 33, however, I get the login prompt and I
> answer enter the username. If I hit Return, nothing happens. If I hot Line
> Feed, the Password prompt is shown.
>
> After I enter the password (all uppercase) Incorrect password is shown.
>
>
>
> Since the prompts are displayed properly, I’m pretty sure the baud rate,
> BPS and stop bits are correct. What else can I check?
>
>
>
> I start agetty this way:
>
>
>
> agetty  -L -U ttyUSB0 110 tty
>
>
>
> The -L means it’s a dedicated line, not dial-in. The -U means the terminal
> is uppercase only and some upper/lowercase conversions should be made.
>
> The port is a USB to serial port (ttyUSB0), baud is 110.
>
> ______________________________________________________________
> GreenKeys mailing list
> Home: http://mailman.qth.net/mailman/listinfo/greenkeys
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:GreenKeys at mailman.qth.net
>
> >>> Jordan Spencer Cunningham's GreenKeys Search Tool:
> https://teletype.net/gksearch
> >>> 2002-to-present greenkeys archive:
> http://mailman.qth.net/pipermail/greenkeys/
> >>> 1998-to-2001 greenkeys archive:
> http://mailman.qth.net/archive/greenkeys/greenkeys.html
> >>> Randy Guttery's 2001-to-2009 GreenKeys Search Tool:
> http://comcents.com/tty/greenkeyssearch.html
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to vk2bea at gmail.com
>
>
>
>
> --
>
>    |\      _,,,---,,_             Michael Katzmann
>    /,`.-'`'    -.  ;-;;,_         NV3Z / VK2BEA / G4NYV
>   |,4-  ) )-,_. ,\ (  `'-'
>  '---''(_/--'  `-'\_)
>
>
> ______________________________________________________________
> GreenKeys mailing list
> Home: http://mailman.qth.net/mailman/listinfo/greenkeys
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:GreenKeys at mailman.qth.net
>
> >>> Jordan Spencer Cunningham's GreenKeys Search Tool:
> https://teletype.net/gksearch
> >>> 2002-to-present greenkeys archive:
> http://mailman.qth.net/pipermail/greenkeys/
> >>> 1998-to-2001 greenkeys archive:
> http://mailman.qth.net/archive/greenkeys/greenkeys.html
> >>> Randy Guttery's 2001-to-2009 GreenKeys Search Tool:
> http://comcents.com/tty/greenkeyssearch.html
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to chuck at rehor.com
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.qth.net/pipermail/greenkeys/attachments/20240109/c6f9807e/attachment-0001.html>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: image001.jpg
Type: image/jpeg
Size: 2059553 bytes
Desc: not available
URL: <http://mailman.qth.net/pipermail/greenkeys/attachments/20240109/c6f9807e/attachment-0001.jpg>