Connecting to the Console Port

There are times when directly accessing the console is required. Perhaps GUI or SSH access has been locked out, or the password has been lost or forgotten.

A null modem cable is a 9 pin D-Shell connector serial cable where the transmit pin on one end connected to the receive pin on the other. These cables can be crafted by hand or purchased inexpensively. A null modem cable pinout is shown in the figure below. USB to serial adapters can be used on client PCs that do not have a standard 9-pin DB-9 serial port.


Null Modem Cable Pinout

Use a terminal program to connect to the device console port. PuTTY is a popular terminal program that is available on various operating systems. Some other choices of terminal programs:

  • Windows - SecureCRT

  • Linux - minicom, dterm, screen

  • macOS - cu, screen, ZTerm


Do not use Windows HyperTerminal

The settings to use within the terminal program are:


115200 baud

Data bits:




Stop bits:


Flow Control:

Off or XON/OFF.


Hardware flow control (RTS/CTS) must be disabled.