How to directly send G-code to printer from a Linux terminal?
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Should it be possible to directly send G-code to the printer serial connection using pipes under Linux?
Example:
echo M106 > /dev/ttyUSB0My controller runs at 250000 baud, I have tried setting the TTY baud rate to 250 kBd with:
stty -F /dev/ttyUSB0 250000But, unfortunately, this particular baud rate appears to be unsupported under Ubuntu, giving the error:
stty: invalid argument ‘250000’
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For direct low-level printer control from a terminal, without specific software, I found the following solution with full credit thanks to user: http://stackexchange.com/users/6463673/meuh
Sharing here as may be of use to other users in the 3d Printing community, and I was unable to source a "complete" solution to this elsewhere.
Step 1)
Create a custom python script that allows you to set arbitrary baud rates (make executable withchmod u+x).#!/usr/bin/python
# set nonstandard baudrate. Original Question: http://unix.stackexchange.com/a/327366/119298
import sys,array,fcntl
# from /usr/lib/python2.7/site-packages/serial/serialposix.py
# /usr/include/asm-generic/termbits.h for struct termios2
# [2]c_cflag [9]c_ispeed [10]c_ospeed
def set_special_baudrate(fd, baudrate):
TCGETS2 = 0x802C542A
TCSETS2 = 0x402C542B
BOTHER = 0o010000
CBAUD = 0o010017
buf = array.array('i', [0] * 64) # is 44 really
fcntl.ioctl(fd, TCGETS2, buf)
buf[2] &= ~CBAUD
buf[2] |= BOTHER
buf[9] = buf[10] = baudrate
assert(fcntl.ioctl(fd, TCSETS2, buf)==0)
fcntl.ioctl(fd, TCGETS2, buf)
if buf[9]!=baudrate or buf[10]!=baudrate:
print("failed. speed is %d %d" % (buf[9],buf[10]))
sys.exit(1)
set_special_baudrate(0, int(sys.argv[1]))Step 2) Run the script to set your baud rate.
./set_custom_baud_rate.py <> /dev/ttyUSB0 250000Step 3) You can now monitor your printer output in a terminal window simply with:
tail -f /dev/ttyUSB0Step 4) And finally, open up a new terminal window, and you can directly send M or Gcode to your printer; example:
echo "M115" >> /dev/ttyUSB0
Can I ask you how is possible that this script works? I don't understand why you use ``<>``, at first I thought was a typo, but modifying the script and opening the serial directly doesn't modify its baudrate.
``<>`` on unix opens a file read+write mode, without truncation, and creates the file if it doesn't already exist. i.e system call: ``open(filename, O_RDWR|O_CREAT)``
For example, ``cat < foo.txt`` it will print the contents of foo.txt, or fail if foo.txt doesn't exist. Whereas ``cat <> foo.txt``,will also print the contents if it exists, but will create the file if it doesn't already exist.
I know what ``<>`` does, but I don't understand why this works for the baudrate: you are setting the baudrate of the file descriptor ``0``, i.e. ``stdin`` not for the serial port.
My understanding is the baudrate is simply the first argument to the script, (i.e ``sys.argv[1]``). If you were to modify the script and hardcode a baudrate, and/or open device using the python equiv. of ``open(filename, O_RDWR|O_CREAT)``, then I, too, would be surprised if that didn't work.
@gipi The "<> /dev/ttyUSB0" argument defines stdin and stdout for the script. When the script operates on stdin, it is operation on /dev/ttyUSB0.
This didn't work for me, nor this guy: https://3dprinting.stackexchange.com/questions/10612/sending-g-code-through-usb-serial-doesnt-work-ender-3?noredirect=1&lq=1 The tail command doesn't output anything The printer seems to thing "ok" is an unknown command, which is its response, right? So why is it receiving its own response as a command?
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Content dated before 7/24/2021 11:53 AM
gipi 5 years ago
Can I ask you how is possible that this script works? I don't understand why you use ``<>``, at first I thought was a typo, but modifying the script and opening the serial directly doesn't modify its baudrate.