I am trying to access a device which is attached to a USB-serial port. The settings are 57600 baud, 8 bit, 1 stop bit, no parity. The device outputs a status line every second and accepts typed commands.
I would like to use GNU screen to initiate 2 way communications, so I am using this command:
screen /dev/ttyS2 57600,cs8
However I just get a blank screen, nothing received from the device.
The communication is fine using teraterm, and I can also do this
stty -F /dev/ttyS2 57600 cs8
cat /dev/ttyS2
to see the status output from the device.
I've tried various combinations of ixon, ixoff, crtscts, and clocal but nothing makes any difference.
How can I determine what the correct command should be?
I am using Cygwin on Windows 10.
I faced the same issue with gnu-screen, I started using plink.exe instead from the PuTTY suite. It's not optimal, but it does the job. In my case serial is just for recovery, not for everyday usage.
Start PuTTY, create a profile with your serial connection.
Name and save the connection.
From cygwin, run: '/cygdrive/c/Program\ Files\ (x86)/PuTTY/plink.exe -load SerialProfile'
Related
Good Morning,
i'm trying to work out the reason to weird characters being outputted in a serial console in linux.
Device:
12d1:15c1 Huawei me906s module in a WWAN to USB adapter (working for normal operations and switches modes etc
The device is connected initially with the PID 15c1 and the output of lsusb -v below:
12d1:15c1 Output
When the device is sent the AT Command of AT^GODLOAD, it switches into download mode which changes its PID too 1568. Output of lsusb -v below:
12d1:1568 Output
OS:
Ubuntu 16.10
Speed:
9600 baud as reported by stty -F /dev/ttyUSB0
Expected: Send AT Commands through /dev/ttyUSB0 with minicom or echo/cat
Result and Description:
When the device is in normal mode (15c1) the device ttyUSB0 is used to send AT Commands, this works perfectly and we can set the chip into download mode (PID 1568)
After Download mode is enabled the chip reboots and reconnects too ttyUSB0, however weird characters show up in minicom and through terminal using 'cat
The weird characters are the same in both monitors and the hex is:
7e 03 00 06 9e 4c 7e
When we send any AT command in download mode the characters show up, except for one AT command as shown in the pictures. This command is significantly larger than any other ones.
Command examples which don't work in GODLOAD:
AT+CMGR?
ATI
-Results in the weird characters ~[][][][]L~
Command which does work:
AT^SIGNVER=5,0,1234567891011121314151617181920, 8502
We have used wireshark to capture the update process on a windows machine.
I actually have screen shots of the operation, commands etc but cannot post them due to limit.
Questions:
-Does the packet size matter for serial commands sent to the module?
-Are we missing some form of a line ending, carriage return or termination to start/end the message correctly?
Thanks for your help in advance
I have software for communicating with a serial device that only runs on Windows 7. My host machine is running Ubuntu 16.04, with Windows 7 in virtual box.
I've managed to set it up using USB device filters in VirtualBox settings so that Windows sees and can communicate with the device.
However I'd like to capture what's being sent to and from the device. I thought something as simple as cat /dev/ttyUSB0 would work but unfortunately when I start VirtualBox I get this in dmesg:
[31199.465270] vboxdrv: ffffffffc0df4020 VMMR0.r0
[31199.653494] vboxdrv: ffffffffc0ef7020 VBoxDDR0.r0
[31199.710573] VBoxNetFlt: attached to 'wlp1s0' / 98:54:1b:04:13:48
[31199.863579] ftdi_sio ttyUSB0: FTDI USB Serial Device converter now disconnected from ttyUSB0
[31199.863674] ftdi_sio 1-3:1.0: device disconnected
So I don't know which file to monitor in /dev anymore. I suppose I might be able to try listen for the communication from Windows, but if I can I'd like to know if it's possible to monitor it from my host machine.
Edit:
This answer helped me for a start. I now get some cool looking stream on the terminal, next step is deciphering it, or if anyone has a better way I'm interested - it looks like the person who answered that question still has deciphering it as a TODO :-)
The fact that it was communicating with software in VirtualBox didn't really matter. This answer got me most of the way just by (as root):
modprobe usbmon
cat /sys/kernel/debug/usb/devices|less and search for device
cat /sys/kernel/debug/usb/usbmon/7u where 7 is the number from "Bus=" in the device table from step 2
From there is was just filtering the output.
A basic way could be just
cat /sys/kernel/debug/usb/usbmon/1u |cut -d\ -f9- | grep ^\n
But the device I was working with was constantly sending lines with just 4 characters, to filter out those I got the address word from the output line, and grepped for that. In my case I only wanted to capture "C" or callback output. I was also filtering for lines that contained more than just the default "0160" that the device was constantly outputting. To try understand the hex output I put a xxd -r -p at the end which gave me:
cat /sys/kernel/debug/usb/usbmon/1u | grep -e 'C Bi:1:005:1\s0\s\w*\s=\s0160\w' | cut -d\ -f8- | xxd -r
Where the grep is
grep -e 'C <address> <someotherstuff> = <always-output-string><anycharacter>
This still gave me this indecipherable junk below, but I don't know the format so I'm stuck here. Maybe the steps to read and filter will be useful for someone
>
O�UDQN��RG_JAMS142E DEFAULT0XXXXXXX�lSTz:�RSDU�vy��������������������������z�fff=�����{6zC"z�u6zC�z�H
;�����C��Af[���RSC�b ISD�EGIN
�CG_IEW0321:0407JUN12S��Z-�$''$'''C'''
I am start learning Linux(CentOs 5.5 kernel 2.6.35.13).
When I try to install a usb wifi stick(TP-Link TL-WN823N,and "lsusb" will show ID 0bda:8178 Realtek Semiconductor Corp..)
It work fine in the window interface( ctrl+shift+F7).
But when I shift to the command window(ctrl+shift+F1),and try to start wifi connection by
wpa_supplicant -Bw -Dwext -iwlan0 -c/etc/wpa_supplicant.conf
I found it kept print logs to screen before I type the command above.
I use
ps axjf |grep wpa_supplicant
to list all related process and find
there is a process start by user "dbus" with the command
/usr/sbin/wpa_supplicant -c /etc/wpa_supplicant/wpa_supplicant.conf -u -f /var/log/wpa_supplicant.log
I dont know whether is this dbus' command that lead the problem.
Below is the screen shot.
kept logging msg:(
Partly fix the problem.
There are two things that make the wifi information keep on loging on the screen.
First, if you use NetworkManager, it will automate run the command under /etc/sysconfig/wpa_supplicant, where you can find the default command write there has no -B parameter which will keep the log in the background.So you can either add an -B to that command or stop NetworkManager and start wifi connection with your own command like in the question.
Second, when you install the driver, the default run status is power saving mode, so when you transfer data with wifi, you can see the screen keeping log infomation like "get into the pw_saving","get out pw_saving" etc.
To fix this, you can shut down the power saving mode like this:
create a file /etc/modprobe.d/8192cu.conf with the following contents:
options 8192cu rtw_power_mgnt=0 rtw_enusbss=0
Or you can rewrite driver code to stop print the info to screen, which I still don't know how to do.
from an ESXi 5.0 shell I would have access to a VM virtual serial interface (VM is running on the ESXi hypervisor). Using netcat (nc) available on ESXi, is possible to connect to the VM virtual serial interface via a UNIX socket binded to it (named pipe).
Now, to emulate a "real" terminal connected to the VM serial interface, I've set the pseudo-terminal in raw mode via "stty raw" command (issued on ESXi shell). Access to the OS running in the VM is fine but I can see that sent characters are echoed back
I've tried passing -echo to stty without lucky: the terminal seem blocked and the only way to recover is disconnect and riconnect again...
Someone can help me ?
I've solved concatenating stty and nc as follows:
stty raw -echo; nc -U 'unix socket'
which is the difference between stty and nc "concatenation" via ";" and just run the two commands one after the other ("stty raw -echo" and then "nc -U unix socket") ?
I'm using Expect to connect to my server over a (virtual) serial port. (HP iLo, to be specific)
When booting from a Linux OS ISO image, you eventually get to the 'boot:' prompt. When my server reaches that prompt, I would like to enter my own custom boot options and press enter. Easy, right?
This is how the boot prompt looks when you're watching my Expect script execute (looks normal):
boot:
However, I have not been able to match 'boot:'. Looking at the Expect Buffer in my logfile, this is what is being captured for that line:
ESC\[25;01HbbESC\[25;01HESC\[25;02HooESC\[25;02HESC\[25;03HooESC\[25;03HESC\[25;04HttESC\[25;04HESC\[25;05H::ESC\[25;05HESC\[25;06H ESC\[25;06HESC\[25;07H"
I think all those control sequences are screwing up my match. If you look closely 'boot:' is actually in there, but it's surrounded by what I believe are ANSI control sequences.
In fact, the logfile is absolutely full of ANSI control characters.
Relevant pieces of the Expect script I've been playing around with:
bash #] expect -d -c '
.....
# SSH to the Virtual Serial Port Management server
spawn ssh user#1.2.3.4
.....
# Access the Virtual Serial Port for the server being booted
send "vsp\r"
.....
# After rebooting the server, when the boot: prompt appears, enter boot options
expect {
"boot:" {send $bootOptions \r\n"}
timeout {send_user "Never found boot prompt\n"; send_user "$expect_out(buffer)"; exit 1}
}
.....
exit'
Any ideas about what the best way to handle those control characters would be? I've tried exporting TERM=dumb and TERM=vt1000 on the machine I'm running the script on. Didn't make much of a difference.
Not sure if this will help, but you could create a wrapper for ssh and exec that instead of ssh and then have
ssh <host> | perl -pe 's/\e([^\[\]]|\[.*?[a-zA-Z]|\].*?\a)//g' | col -b
perhaps take out the col -b which filters newlines if you don't need that.