Altair8800 or AltairZ80 SIMH and connecting console to a physical serial port?

[Joseph Corda]

Greetings
Using SIMH and Altair8800 to develop a monitor program as away to learn 8080 assembly language.  So far made good progress .. but I would now like to test the monitor interaction using a terminal program.

SIMH is running on a Ubuntu 24.04  Linux system and I currently have a USB to 4 port 
Star-Tech serial hub offering up /dev/ttyUSB0-3 (which has been working great).

Below is my Altair8800/Z80 config file...
If I run ./Altair8800 TestConfig with the "set console" commented out my monitor program works as expect in the SIMH console screen.

If I include the "set console" and connect minicom -D /dev/ttyUSB0 -b 9600 ...I do not see any console messages on either SIMH console or minicom.   Next I tried to connect a serial cable between ttyUSB0 and a Windows 10 system running Teraterm and still I see nothing.  (I also tested using null modem adapter just in case)

Finally to take my monitor program  out the equation I tested using ALTMON and get same results.

I'm sure I am missing something simple.... any suggestions would be appreciated 
Happy New Year!
Joe

TestConfig SIMH config:
==========================

reset

;Works fine to SIMH console with this next line commented out

set console serial=/dev/ttyUSB0;9600-8n1
set cpu noitrap
set cpu z80
reset cpu
load JoeMON.rom f000
go f000
;load ALTMON.rom f800
;go f800

[Terry Fox]

First thing I always check anytime I have problems with a Linux box hardware/software is to check permissions on ALL affected things.  I can't tell you how many times stuff wouldn't work together because a permission problem, even with USB serial ports.

Yay Linux....

[Joseph Corda]

Agreed .. permission was one of the first things I check on the ttyUSB devices.. but I will recheck now 
Thanks for the suggestion
Joe

[Joseph Corda]

ITS ALIVE !!!
Thanks to Patrick Linstruth for his help.. as he guided me to the solution. 
A few points to mention for anyone trying this in the future on a linux system...

• I needed a null modem  between the Serial ports. ttyUSB0 and ttyUSB1
• Added these setting to my SIMH Altair8800 config file
  • attach m2sio0 connect=/dev/ttyUSB0
  • set m2sio0 baud=9600
• Setup minicom ttyUSB1 as 9600,8n1
• Double check you wiring (my breakout box was cause of an issue)
• Double check your permissions to ttyUSB ports (those happen to be correct in my setup)

Wishing everyone a Happy New Year!
Joe