Ed,?
I have Ubuntu and Java installed, but JMRI cannot see any serial ports, does anyone have ideas on how to expose them, the JMRI instructions say to change the permissions, but it expects you to know the addresses, and I am not sure Chrome OS makes them available to crouton/Ubuntu.
Have you read and tried the instructions on "Using the Serial Ports" down near the end under "Notes" at the following link?
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It not only gives instructions but specifically warns that changing serial port permissions will not solve the problem.
I'm not guaranteeing they'll work under Chrome OS...
Dave in Australia