Unix Server Tech Knowledge Base

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====== Serial Port ======

Very few workstations and laptops have serial ports, but they are still useful for connecting to network switches, routers, and servers.

I use a USB to Serial converter from Prolific Technology, Model PL2303 Serial. So far, I have not found anything which doesn't support it: Windows, Linux, even my Chromebook (with the Linux subsystem enabled) work just fine.

Most modern network devices use an RJ-45 connector. It looks like a network port, but it is wired as a serial port. HP has a cable with a DB-25 on one end (old school serial port) and an RJ-45 on the other, but that one generally sucks. Get one of the ones that Cisco has. Hint, it is normally light blue in color.

I plug the Cisco cable into my PL2303, the plug the other end of the Cisco into the device I want to control.

Following instructions are for a Chromebook, but should work similar for laptops or even a workstation.

  - On a Chromebook, enable the Linux subsystem
  - Download and install a serial communication software. I like minicom, others hate it and go with something else, but I'll describe minicom
  - Plug the USB to Serial device in. In my case, the first time, it asked if I wanted it available to ChomeOS or Linux, and I chose Linux
  - As root (sudo su), start minicom <code bash>minicom -o -D /dev/ttyUSB0</code>
    - The -o says "don't initialize this as a modem"
    - The -D sets the device (try <code bash>ls /dev</code> to find the device name
  - Configure minicom by pressing ^A-O
    - Set baud to 9600 (to be safe)
    - Set bits to 8N1
    - Set hardware handshaking and software handshaking off
    - exit, then save as default
  - Turn on the device (a network switch in my case)
  - If all goes well, you'll see the boot process start.