How to Use PuTTY for a Serial Connection

By Gareth Downes-Powell

PuTTY is an open source terminal emulator, used to connect to SSH, telnet and similar servers for remote administration. Developed by Simon Tatham, who released the first version in 1999, PuTTY has been upgraded a number of times over the years to add new features and fix bugs. PuTTY also enables you to connect to a device attached to the serial port on the computer, sending typed commands to the serial device and displaying the reply. This is useful for debugging networking hardware equipped with serial ports, or connecting to microcontrollers and other electronics devices.

Step 1

Click on the Windows "Start" menu, and then click on the "PuTTY" program group to open. Click on the "PuTTY" icon to launch the program.

Step 2

Click on the "Serial" radio button to set the connection type.

Step 3

Type the COM address for the serial port in the "Serial Line" box to select the COM port the serial device is attached to. For example, COM1 or COM2. Type the baud speed the serial device operates at in the Speed box; for example 9,600 or 115,200. If you are unsure of the baud rate to use, check the documentation for the serial device. If no documentation is available, start at a high speed such as 115,200, and work your way down until you can connect to the device successfully.

Step 4

Click on the "Serial" menu item under Connection in the Category menu tree on the left side of the PuTTY window to change the default parameters, if necessary. You can set the number of data bits and stop bits, as well as the parity and flow control method used to connect to the serial device. If you are unsure of the settings to use, leave these set to the default values, which will work in the majority of cases.

Step 5

Click the "Open" button to initiate the connection to the serial device. You may see some introductory text sent from the serial device when the device has connected, but some devices do not respond until you send a command. Once you have typed some data and pressed the "Enter" key to transmit to the serial device, you should see a response from the device displayed in the PuTTY window.

Step 6

Close the PuTTY window by clicking on the close button to end the serial connection when required.