Create Virtual Serial Port in Linux
Create Virtual Serial Port with socat & Python in Linux.
Virtual serial ports are a logical representation of physical serial ports. These ports do not connect with the serial port. A virtual serial port allows us to emulate a physical serial port, thereby removing the requirements of cable and physical communication interface.
Additionally, a virtual port allows software packages to communicate with internal memory using the null modem emulator. The null modem emulator is a virtual driver for Linux that enables virtual serial port communication.
There are several ways to create a virtual serial port in Linux to test and debug serial communication protocols.
socat
Install
socat is usually available by default, but we can still install it manually with apt-get or yum.
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#Debian-based
sudo apt-get install -y socat
# RHEL-based
sudo yum install -y socat
Create Virtual Serial Port
For instance, to create two pseudo terminals with the debug mode on:
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$ socat -d -d pty,rawer,echo=0 pty,rawer,echo=0
The -d -d option prints errors, fatals, warnings and notices. The two pty,rawer,echo=0 create two pseudo terminals under /dev/pts.
Python
A python script can create virtual serial ports.
Here’s a simple example:
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import pty
import os
import select
def mkpty():
master1, slave = pty.openpty()
slaveName1 = os.ttyname(slave)
master2, slave = pty.openpty()
slaveName2 = os.ttyname(slave)
print("\ndevice names: ", slaveName1, slaveName2)
return master1, master2
if __name__ == "__main__":
master1, master2 = mkpty()
while True:
rl, wl, el = select.select([master1, master2], [], [], 1)
for master in rl:
data = os.read(master, 128)
print("read %d data." %len(data))
if master == master1:
os.write(master2, data)
else:
os.write(master1, data)