How to use Prolific RS232 USB to Serial Converter with Ubuntu

Using ubuntu 14.04 I didnt need to install any drives. Just plug and play. Also works with Ubuntu 11 (according to link) so should work with Ubuntu 11+ in general.

First plug in the Prolific to the device. My setup looks like this.

Computer—>Prolific—>DE9 cable—>Device

The DE9 cable is your typical null-model cable. That runs on RS232 standard. DE9 sometimes wrongly called DB9 cable. DB9 is the name for the port. DE9 is the name of the cable.

Anyhow here is the linux commands:

First check that it detects:
dmesg | grep tty

It should appear as a /dev/ttyUSB0 (or similar)

Now lets setup minicom (you can also use programs like screen). Minicom is best because you can change baud rate and stuff on the fly without exiting.

apt-get update
apt-get install minicom

Setup the initial connection parameters (these will be the defaults that last throughout history, you can of course change these)

sudo minicom -s

Note: note the use of sudo because /dev/ttyUSB0 probably has permissions only for root (you can ofcourse do some “sudo chmod 666 /dev/ttyUSB0” type of commands to allow for regular user access)

When in “minicom -s” (minicom setup) navigate with keyboard and mouse

1. Go to “Serial Port Setup
2. Setup your device (first line) to say “/dev/ttyUSB0” (without the double quotes of course).
3. Change any other settings like baud rate from 9600 to 115200 (usually thats the only setting you have to change – stop bit and the like usually gets left as default)
4. Exit out of the “Serial Port Setup” to get back to the main menu of “minicom -s” (minicom setup)
5. “Save setup as dfl” to save the settings as default.
6. Select Exit to get out of minicom

Now open up minicom and you should be faced with the serial interface

sudo minicom

It will tell you that can do special commands using

CONTROL-A then press a <key>

CONTROL-A then press Z: to see all of the keys
CONTROL-A then press C: to clear the screen
CONTROL-A then press P: to change baud rates on the fly (usefull if your device goes thru different baud rates through its boot up phases, like at POST its at 9600 but post GRUB its at 115200)
CONTROL-A then press Q: to quit

Extra notes:
– When trying to find a working port or changing devices press ENTER after physical connection to see if you get any text
– If you get garbage text, try to change baud rates (look up baud rate of the device to find out the baud rate that you need to be configure for)
– The baud rate of the device your connecting to is what matters (not the baud rate of your PC)
– If your messing around with the physical connectiong, keep the USB end connected to the PC (dont remove that). Instead play around with the serial cable end.
– If trying to get an unknown device to work, first make a known device work using the above setup, then while keeping the Prolific converter in USB port, just dislodge the serial cable from the known good device to the unknown device (and hit enter)
– This method also works if you have a UART cable daisy chained off such as this:
Computer—–>Prolific—–>DE9 cable—–>Serial 2 UART convert——–>UART—–>Device

Note: for more help on using minicom:

One thought on “How to use Prolific RS232 USB to Serial Converter with Ubuntu

  1. Thanks for the write up. I didn’t think about chmod 666 /dev/ttyUSB0. This worked for me, using PuTTY.

    Had to go into PuTTY settings and turn off flow control (on by default) and set the default serial to /dev/ttyUSB0.

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