Virtual serial line (RS232) on linux with socat and pyserial

README.md

Virtual serial line

Virtual serial line on linux with socat, python server & client

Run on terminal 1:

socat -d -d pty,raw,echo=0,link=/tmp/cryocon_simulator pty,raw,echo=0,link=/tmp/cryocon

Run on terminal 2:

python simulator.py

Run on terminal 3:

python client.py "*IDN?"

References

stack overflow reference

Alternatives:

• example
• nullmodem
• tty0tty

client.py

import sys
import serial
DEFAULT_ADDR = '/tmp/cryocon'
DEFAULT_CMD = '*IDN?'
args = len(sys.argv) - 1
if args == 0:
    addr, cmd = DEFAULT_ADDR, DEFAULT_CMD
elif args == 1:
    addr, cmd = DEFAULT_ADDR, sys.argv[1]
else:
    addr, cmd = sys.argv[1:3]

cmd += '\n'
s = serial.serial_for_url(addr)
s.write(cmd.encode())
print(s.readline())

simulator.py

import sys
import logging

import serial

DEFAULT_ADDR = '/tmp/cryocon_simulator'

logging.basicConfig(level=logging.INFO)

addr = sys.argv[1] if len(sys.argv) > 1 else DEFAULT_ADDR

conn = serial.serial_for_url(addr)
logging.info(f'Ready to receive requests on {addr}')
while True:
    request = conn.readline()
    logging.info('REQ: %r', request)
    request = request.strip().decode().lower()
    reply = 'Cryo-con,24C,305682,1.05A\n' if request == '*idn?' else 'NACK\n'
    reply = reply.encode()
    logging.info('REP: %r', reply)
    conn.write(reply)

virtual_serial_line.sh

# creates the PTYs
socat -d -d pty,raw,echo=0,link=/tmp/cryocon_simulator pty,raw,echo=0,link=/tmp/cryocon