Setting The Correct Port - Espressif ESP8266 User Manual

E. Setting the Correct Port
Serial interface: At the hardware level the ESP8266 is programmed through a serial interface.
In short this is a very common communication interface which normally requires three lines:
transmit (TX), receive (RX) and ground (GND). Both devices involved in the communication
need to agree on the rate the characters are sent over the wire. This rate is usually measured
in BAUD. 10 BAUD is equal to 1 character per second. Your average PC or Mac doesn't have
such a serial interface, so how can we program the ESP8266? This is done through a Serial-
to-USB converter. Some ESPs already come with a built-in converter; others need an external
one for programming.
In an earlier step, you already installed the drivers for this converter. If everything went well
and the board is plugged into your computer you should now be able to select the serial
connection. It should show up in the Menu under Tools > Port. On my Mac the device is
called /dev/cu.SLAB_- USBtoUART. On a PC it should be listed as a COM port labelled COM#
(where # is some number).
If you cannot see a device that looks like the NodeMCU, try to unplug the ESP module and
re-plug it after a few seconds. Also try a different USB socket. If that doesn't help consider
restarting your computer... Make sure that you installed the driver as mentioned in the chapter
about drivers.