Testing the serial ports

You will need:

• The machine to be tested

• Screen

• Keyboard

• Crossover or "null modem" serial cable

• Connection to the internet

Step 1 - Connect the peripherals

Connect the screen, keyboard and serial cable, then power the machine up. Log on to the desktop.

Step 2 - Prepare the test

First, make sure that the screen program is installed. Open a Terminal window and run the following commands.

sudo apt update
sudo apt install -y screen

Now open a second Terminal window.

Step 3 - Run the test

Run one of the following commands in each of the terminal windows:

sudo screen /dev/ttyUSB0 19200
sudo screen /dev/ttyUSB1 19200

After running each command, the console will go blank with just a blinking cursor. Now run the following tests

• Click on the first terminal and type some text. It should appear in terminal 2

• Click on the second terminal and type some text. It should appear in terminal 1

If either of these tests fail, please double check the isolated port has been correctly installed.

Assuming both tests pass, simply close the terminal windows.