1. To test a serial port in MAC OSX first download the free CoolTerm application
2. Open Cool Term and click options.
3. In the port dropdown Brainboxes Serial ports appear with the name “cu.usbserial-randomcharacters”
4. Select the port to test with default settings.
5. Press ‘Connect’ on cool term.
6. Put a loop-back on the Connector of the device under test, for an RS232 serial port this can be performed by shorting pins 2 and 3. See: How do I create a loop back connector?
7. Type into the CoolTerm console, the characters should appear on the screen