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