huanyang vfd modbus ok but M3 gcode not working on 2.8 master

rebooted multiple times and ran "ps -lt tty0" to see if there were any other processes using the tty and had none running. The tty port does work with the vfd in the debian 6 instance of linuxcnc. Thanks for the suggestion.

You might not have permissions to access it.

try ls -l /dev/ttyS0


You could trybut I don't think it will stay after reboot.

you're correct about the permissions as it is root access only. Ill try this later today from the root user. thanks

Continuing this thread, I did log in as root user and checked the tty ports and they are not being used by other processes and shown as idle. Here is the message being generated in the linuxcnc_print.text file:
RUN_IN_PLACE=no
LINUXCNC_DIR=
LINUXCNC_BIN_DIR=/usr/bin
LINUXCNC_TCL_DIR=/usr/lib/tcltk/linuxcnc
LINUXCNC_SCRIPT_DIR=
LINUXCNC_RTLIB_DIR=/usr/lib/linuxcnc/modules
LINUXCNC_CONFIG_DIR=
LINUXCNC_LANG_DIR=/usr/share/linuxcnc/tcl/msgs
INIVAR=inivar
HALCMD=halcmd
LINUXCNC_EMCSH=/usr/bin/wish8.6
INIFILE=/home/mike/linuxcnc/configs/my-mill-25Oct18/my-mill-25Oct18.ini
PARAMETER_FILE=linuxcnc.var
TASK=milltask
HALUI=halui
DISPLAY=axis
Starting LinuxCNC server program: linuxcncsvr
Loading Real Time OS, RTAPI, and HAL_LIB modules
Starting LinuxCNC IO program: io
Starting HAL User Interface program: halui
Killing task linuxcncsvr, PID=1900
Removing HAL_LIB, RTAPI, and Real Time OS modules
Removing NML shared memory segments

I guess copy the terminal output.. I didn't see any errors listed in what you posted.

Let me say thanks for hanging in there on this and in reading the LinuxCNC documentation, as well as this output message, is it possible the "uspace" is not configured properly?
LINUXCNC - 2.7.14-41-g85b3fd171
Machine configuration directory is '/home/mike/linuxcnc/configs/my-mill-25Oct18'
Machine configuration file is 'my-mill-25Oct18.ini'
Starting LinuxCNC...
Found file(REL): ./my-mill-25Oct18.hal
Refusing to run as root without fallback UID specified
To run under a debugger with I/O, use e.g.,
sudo env RTAPI_UID=`id -u` RTAPI_FIFO_PATH=$HOME/.rtapi_fifo gdb rtapi_app
./my-mill-25Oct18.hal:4: waitpid failed /usr/bin/rtapi_app trivkins
./my-mill-25Oct18.hal:4: /usr/bin/rtapi_app exited without becoming ready
./my-mill-25Oct18.hal:4: insmod for trivkins failed, returned -1
Shutting down and cleaning up LinuxCNC...
Refusing to run as root without fallback UID specified
To run under a debugger with I/O, use e.g.,
sudo env RTAPI_UID=`id -u` RTAPI_FIFO_PATH=$HOME/.rtapi_fifo gdb rtapi_app
LinuxCNC terminated with an error. You can find more information in the log:
/root/linuxcnc_debug.txt
and
/root/linuxcnc_print.txt
as well as in the output of the shell command 'dmesg' and in the terminal

Don't try to run from the root account. We can fix the permissions of /dev/ttys0 so you can access it from the user account

OK, I did change the permissions for /dev/tty and that resolved the starting LinuxCNC issue. I had one more problem with not being able to get out of E Stop. I resolved that by adding" -15-not" to the estop pin in the ini file. I'll run some g-code later today but the original problem seems to corrected. Thank you all for the help.