WSL and serial port - windows

Question

I am using Win10 and Linux Ubuntu on WSL 2.0.
For testing purposes of some programs, I would like to use the serial port of my PC in "loopback" with Linux running through WSL.
Basically I would like a process on Linux/WSL to be able to send/receive data from a Windows process or vice versa, through serial port, but without any hardware hack.
Of course I have already tried to set the Windows process serial as "COM1" (as indicated by the Windows resource manager) and the Linux port on WSL as "/dev/ttyS1", but apparently it doesn't work.
Is there any way to do this?

Answer 1

Status update
According to other answers, it seems that the addition of product functions has made it possible to use USB devices with WSL2.
Especially in v5.10.93.2, it seems that drivers for two types of USB serial interface chips are built in.
linux-msft-wsl-5.10.93.2
Enable CH341 and CP210X USB Serial drivers
linux-msft-wsl-5.10.60.1
Enable USB over IP support
Enable USB kernel configuration options for interacting with an Arduino over USB
The following is outdated information.
WSL 2.0 does not support serial ports.
Exceptions for using WSL 1 rather than WSL 2
WSL 2 does not include support for accessing serial ports. Learn more in the FAQs or in WSL GitHub repo issue on serial support.
The following options are possible.
Revert to WSL 1.0 and use
Use third-party products
For example, there seems to be something like this.
Windows USB Server
VirtualHere USB Server
Although it is a Japanese article, there is such a trial article.
WSL2でUSBデバイスを認識させる
Also, if you want to communicate between serial ports even if WSL2 cannot recognize USB serial, this method is also available.
Connecting to serial port (com port) over network
And as you can see from the above explanation, if you want to communicate between the processes of each OS, you can simply use a TCP/IP socket instead of the above mechanism.

Answer 2

Run this in PowerShell or CMD to see if you use Version 1:
C:\>wsl -l -v
NAME STATE VERSION
* Ubuntu Running 1
If yes, here's some tested working code to read COM14 from linux command prompt:
#!perl -w
use strict;
$|=1; # autoflush
use Device::SerialPort;
my $port = Device::SerialPort->new("/dev/ttyS14");
$port->baudrate(115200); # Configure below to match your device
$port->databits(8);
$port->parity("none");
$port->stopbits(0);
$port->debug(1);
$port->read_char_time(0); # don't wait for each character
$port->read_const_time(1); # 0.001 second per unfulfilled "read" call
while (1) {
my ($count_in, $str_in) = $port->read(255); # Supposedly must be 255 always
if($count_in) {
print $str_in;
}
}
If you are running WSL2, you can backup, convert or copy your distribution to WSL1 via wsl --export, wsl --import, and wsl --set-version. See this question among others for details.