- Apr 26, 2017 Windows processes cannot access a serial port after an Interix process uses the serial port. Content provided by Microsoft. (Services for UNIX QFE) Symptoms. After an Interix process uses a serial port and then closes, Microsoft Windows processes cannot access the serial port. For example, after the Igetty process uses a serial.
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- Cant Select 'Serial Port' From Arduino Menus Or Program Arduino Uno, Windows 7. Pages: [1] Topic: Cant Select 'Serial Port' From Arduino Menus Or Program Arduino Uno, Windows 7 (Read 43233 times) previous topic - next topic. You should be able to access TOOLS>SERIAL PORT. Select whatever port is listed. I only had one choice, COM4.
Direct serial port access I have older program that needs a direct connection to serial (rs233) port. It does not work in windows 7 because there is not direct access to serial port hw. Endlessly Evolve. Home; News; Review. Action Figure; Games; Hardware; Movie; Preview; Tutorial. Action Figure. Hi all, maybe not entirely sure if this is a labview question, but i was using labview when it happened. Cannot open com port. Active Participant 05.
Is there a way to connect to a serial terminal just as you would do with SSH? There must be a simpler way than tools such as Minicom, like this
I know I can cat
the output from /dev/ttyS0
but only one way communication is possible that way, from the port to the console. And echo
out to the port is just the same but the other way around, to the port.
How can I realize two way communication with a serial port the simplest possible way on Unix/Linux?
15 Answers
I find screen
the most useful program for serial communication since I use it for other things anyway. It's usually just screen /dev/ttyS0 <speed>
, although the default settings may be different for your device. It also allows you to pipe anything into the session by entering command mode and doing exec !! <run some program that generates output>
.
Background
The main reason why you need any program like minicom
to communicate over a serial port is that the port needs to be set up prior to initiating a connection. If it weren't set up appropriately, the cat
and echo
commands would not do for you what you might have expected. Notice that once you run a program like minicom
, the port is left with the settings that minicom
used. You can query the communication settings using the stty
program like this:
If you have done it right; after booting the computer and before running any other program like minicom,
the communication settings will be at their default settings. These are probably different than what you will need to make your connection. In this situation, sending the commands cat
or echo
to the port will either produce garbage or not work at all.
Run stty
again after using minicom
, and you'll notice the settings are set to what the program was using.
Minimal serial communication
Basically, two things are needed to have two-way communication through a serial port: 1) configuring the serial port, and 2) opening the pseudo-tty read-write.
The most basic program that I know that does this is picocom
. You can also use a tool like setserial
to set up the port and then interact with it directly from the shell.
I found a way using a shell script here that put cat
as a background process and a while loop that read the user input and echo
it out to the port. I modified it to be more general and it fitted my purpose perfectly.
If UUCP is installed on the system, you may use the command cu, e.g.
Try http://tio.github.io
'tio' is a simple TTY terminal application which features a straightforward commandline interface to easily connect to TTY devices for basic input/output.
Typical use is without options. For example:
Which corresponds to the commonly used options:
It comes with full shell auto completion support for all options.
ThomasThis script is based on another answer, but sends everything over the serial port (except Ctrl+Q), not just single commands followed by Enter. This enables you to use Ctrl+C or Ctrl+Z on the remote host, and to use interactive 'GUI' programs like aptitude or alsamixer. It can be quit by pressing Ctrl+Q.
BTW, the putty package (which does run on Linux) does include serial support.
mdpcmdpcPutty works well on Linux and offers some convenience, especially for serial communications. It has one drawback I haven't been able to directly solve: no copy-paste from the Putty window itself. The windows version has a lovely auto-copy to clipboard on highlight, right-click to paste behaviour (and there are excellent plugins for both chrome and firefox to enable the same behavior), but on Linux, no copy love AFAIK.
If the lack of copy is a problem (it is for me) then turn on logging in putty and open a standard terminal window and # tail -f putty.log
and bidirectional text is available for standard copypasta action.
Another issue that can occur is that your user account may need to set to the 'dialout' group to access the serial port.
GAD3RIt depends on what you want to do. Do you want to run a shell or applicaiton interactively from the terminal, connect out to another computer over the serial line, automate communication with a device over a serial port?
If you want bidirectional communication then I presume you want something interactive with a human on the terminal. You can configure the system to allow logins from a terminal over a serial port by seting up a getty(1) session on the serial port - getty is the tool for setting up a terminal and allowing logins onto it. Put an entry in your inittab(5) file to run it on the appropriate serial port on a respawn
basis.
If you want to connect to a device and initiate automated two way conversations then you could see if expect will get you what you want. Use stty(1) to configure the port to the right parity, baud rate and other relevant settings.
If you want to communicate interactively with another computer over the serial port then you will need terminal emulation software. This does quite a lot - it sets up the port, interprets ANSI or other terminal command sequences (ANSI was far from being the only standard supported by serial terminals). Many terminal emulators also support file transfer protocols such as kermit or zmodem.
The ins and outs of serial communications and terminal I/O are fairly complex; you can read more than you ever wanted to know on the subject in the serial howto.
As mentioned before you can try picocom. The latest release (2.0) can also be used (safely) to set-up a 'terminal server' since it no longer permits shell command injection. See:
You might want to take a look at
Pro: doesn't have obvious security problems like minicom or picocom (if you don't have a problem giving the users shell access, no problem, but you most likely do have one if you want to set up a terminal server...)
You need to be sure to have the correct read write permits on the device, you could see it with:
I rely on the script you found and made some modifications.
For the development systems I've used by now, they used to need:
- None parity and
- One stop bit
Those values are the default ones in the script.
So in order to connect, you can use it as simple as follows:
Example:
Script:
P.S.: You need to know which kind of line feed is using your receiver system since this will determine how you'll need to send the commands in my case I needed a Windows like LF, means that I need to send
ASCII values for:
- LF : 0Ah, line feed 'n'
- CR : 0Dh, carrige return 'r'
- BS : 08h, back space '<-'
As it is not mentioned here already, I'd also mention socat
- more info in https://stackoverflow.com/questions/2899180/how-can-i-use-com-and-usb-ports-within-cygwin :
or
(though, I've had the problem of stopping it once it starts running, under MSYS2 on Windows)
Another easy option is to access the machine over ssh with the -X
flag and run a program such as putty or gtkterm.
So:
It should launch the graphical interface on your client PC and from there you can access the serial port as if you would be in the host.
Disclaimer: Only tried this with ubuntu machines. I'm guessing that it won't work with machines without graphic interfaces.
From the ssh manual:
-X
Enables X11 forwarding. This can also be specified on a per-host basis in a configuration file. X11 forwarding should be enabled with caution. Users with the ability to bypass file permissions on the remote host (for the user's X authorization database) can access the local X11 display through the forwarded connection. An attacker may then be able to perform activities such as keystroke monitoring. For this reason, X11 forwarding is subjected to X11 SECURITY extension restrictions by default. Please refer to the ssh -Y option and the ForwardX11Trusted directive in ssh_config(5) for more information.
-Y
Enables trusted X11 forwarding. Trusted X11 forwardings are not subjected to the X11 SECURITY extension controls.
So use -Y
if security is an issue.
Usb Port
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Hello Novicexyz,
If your unable to run the program in windows 7, let’s try to install the programs in compatibility mode and check if it works.
Program compatibility is a mode in Windows that lets you run programs written for earlier versions of Windows. Most programs written for Windows XP also work in this version of Windows, but some older programs might run poorly or not run at all.
Most programs written for Windows Vista also work in this version of Windows, but some older programs might run poorly or not at all. If a program written for an earlier version of Windows doesn't run correctly, you can try changing the compatibility settings for the program, either manually or by using the Program Compatibility troubleshooter.
Note: Make sure that this program can only be used in windows 7 professional, Enterprise and Ultimate edition.
To install the programs in XP compatibility mode, please follow the steps below:
Serial Port Pinout
1. Right click on the program icon and select properties.
2. Now click on the compatibility tab.
3. Under compatibility mode check “Run this program in compatibility mode for”.
4. From the drop down menu, select Windows Xp.
Refer this link for more information:
Make older programs run in this version of Windows
Serial Port Adalah
I hope this information helps. Please get back to us if you have any more questions about this issue.
Centos Access Serial Port
Thanks and Regards
Mir - Microsoft Support
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