CoolTerm : Terminal Program for Serial Port Connection

Advanced electronic devices offer more than one way to communicate with them. For example, a typical WiFi router has USB port, an Ethernet port and maybe the RJ25 port for the ADSL variants. But inside the router, there is usually a low level communication port which is done through a UART (universal asynchronous receiver & transmitter) pinout. Some of the electronic boards have four pins indicating VCC, RX, TX and GND while others just leave it to the user to solder the wiring on the labeled points.

For such a four-pin interface, we need a special device called USB-to-TTL adapter which is easily available from any online shopping site such as Amazon or eBay. But even then we need a terminal software so that we can actually send and receive commands to the serial communications port.

In the older versions of Windows, there was a terminal application included but it has been discontinued. Now you can use a free program called CoolTerm which offers many advanced features for serial communications with electronics devices.


CoolTerm is a easy-to-use serial port terminal application. It has been designed keeping in the newbies in mind but professionals can use it too. We can use it with any hardware connected to serial ports such as routers, modems, mobile phones, servo controllers, robotic kits, smartwatches, GPS receivers, micro-controllers, and more.

Establishing a connection is very easy with the help CoolTerm. All you have to do is select a COM port, baud rate and click on the Connect button in the toolbar. The baud rate is very important because without the correct baud rate, data will not be interpreted accurately.

In the usual terminal programs we can see only the ASCII output from the port, but in CoolTerm we can switch between the plain, hex and chart view. The plain view shows the regular text, the hex view shows the data in hexadecimal format and the chart view shows the data received as data points.

CoolTerm is a portable application for Windows and is also available for Linux, Mac, and Raspberry Pi. They also provide builds that work on very old versions of Windows such as Windows XP.

You can download CoolTerm from