Virtual serial port pairs in Mac OSx

I was unable to find any apps to create virtual serial ports for later versions of Mac OSx eg., Catalina.

There is a partial solution using the linux socat utility. It will create functioning vsp’s but the ports will not be detected by most apps, like Max/MSP.  I tried setting a symlink to files in /dev using tty. and cu. prefixes. eg., /dev/tty.x1. But apps that look for serial ports still couldn’t detect the vsp’s.


  1. download and install socat using macports or brew. eg., “sudo port install socat”
  2. Disable SIP (system integrity protection). In Catalina, reboot holding cmd+r. Then type: “csrutil disable” into a terminal window. Reboot – Note: you probably don’t need to do this if you aren’t setting up a link in /dev – which so far doesn’t work anyway
  3. Run one of the following commands:

socat -d -d pty,raw,echo=0 pty,raw,echo=0

sudo socat -d -d pty,link=/dev/tty.x0,raw,echo=0,user=tkzic,group=staff pty,link=/dev/tty.x1,raw,echo=0,user=tkzic,group=staff

What works and what doesn’t

After setting up the ports, you can send data in one port and out the other, for example, type the following into 2 different terminal windows.

cat /dev/ttys004

echo “Hello World” > /dev/cu.x1

This works great. But, so far, using sym links – the ports don’t show up in any app that accesses serial ports. Still working on this…

Using socat you can also setup a serial/tcp pair – this may be a solution for some projects.