Cygwin serial port permission denied

Cygwin serial port permission denied

I am trying to log data to a text or csv file from my serial port (data
which is showing in arduino serial monitor). Arduino is connected via USB,
I am using windows 7 and cygwin, and I have set the appropriate
permissions to the serial port /dev/ttyS2 (COM3) with chmod 755:
$chmod 755 ttyS2
$ ls -l ttyS2
crw-rw-rw- 1 Libby None 117, 2 Aug 27 12:23 ttyS2
I have installed PySerial, and when I execute command to write to a text
file, I get an error with permissions denied:
$ python -m serial.tools.miniterm /dev/ttyS2 >> templogger.csv
could not open port '/dev/ttyS2': could not open port /dev/ttyS2: [Errno
13] Permission denied: '/dev/ttyS2'
Why is permission denied? The serial port does not seem to be part of a
group (ls -l output says "None"), I am the owner ("Libby") and I have
read/write access to the port ("crw...").
Thanks in advance for any advice.