I found your post and since there was no polarity info on those points, I searched for colorcode for 3 these wires.
attached pic..
bought
https://www.amazon.in/dp/B077D27PNJ/..._t3_B006JKNWLE
after installing drivers. I used on macbook..
Code:
sudo cu -s 115200 -l /dev/tty.SLAB_USBtoUART
sudo cu --parity=none -s 115200 -l /dev/tty.SLAB_USBtoUART
sudo cu -s 38400 -l /dev/tty.SLAB_USBtoUART
sudo cu --parity=none -s 38400 -l /dev/tty.SLAB_USBtoUART
didnt work.. Swapped rx/tx still no luck.
I used putty on windows with same config in driver config panel ie 38400 and no parity.. nothing appeared in putty for that COM port..
I found that UART module is fine as I got my wifi router TL-WA5210G serial console with this unit afterwards