The **serial library** supports [serial communication](https://en.wikipedia.org/wiki/Serial_port) between the @boardname@ and another computer. Basically, this allows you to send data from the @boardname@ to your own computer. This is very useful for debugging purposes: you can add `write line` statements in your code and see them display on your computer as the program executes.
You must install a device driver (for the computer to recognize the serial interface of the @boardname@); then, you must also install a terminal emulator (which is going to connect to the @boardname@ and read its output). Here's how to do it:
* Follow instructions at https://developer.mbed.org/handbook/Windows-serial-configuration in order to install the device driver
* Install a terminal emulator; we recommend [Tera Term](https://ttssh2.osdn.jp/index.html.en). At the time of this writing, the latest version is 4.88 and can be downloaded [from here](http://en.osdn.jp/frs/redir.php?m=jaist&f=%2Fttssh2%2F63767%2Fteraterm-4.88.exe). Follow the instructions from the installer.
* Check "Serial"; in the dropdown menu, pick the COM port that says "mbed Serial Port". Hit `Ok`.
* In the menus, hit `Setup` > `Serial Port` and set the baud rate to `115200`.
You should be good. Feel free to hit `Setup` > `Save Setup` in the menus to erase the default configuration file with a new one so that you don't have to type in the settings again.
Please note that Windows will assign you a different COM port if you plug in another @boardname@. If you're juggling between @boardname@s, you'll have to change the COM port every time.
If you prefer another terminal emulator (such as [PuTTY](http://www.putty.org/)), here are some instructions.
* Open Windows's [Device Manager](https://windows.microsoft.com/en-us/windows/open-device-manager); expand the section called "Ports (COM & LPT)"; write down the com number for "mbed Serial Port" (e.g. COM14)
* Open PuTTY; on the main screen, use the following settings: Serial / COM14 / 115200. Replace COM14 with the COM port number you wrote down previously. Feel free to type in a name and hit "Save" to remember this configuration.
![](/static/mb/serial-library-0.png)
* (optional): in the "Terminal" section, check "implicit cr in every lf"
*`ls /dev/cu.*` will return to you a list of serial devices; one of them will look like `/dev/cu.usbmodem1422` (the exact number depends on your computer)
Theoretically, you can dump more sophisticated data and then read it back in the event that two @boardname@s should be connected to each other over serial. We have not tested this scenario yet as we have yet to expose functionality that allows re-routing the serial ports to the edge connector.