Looked into this a little more and can confirm that the problem lies with the Arduino version.
Download an older version, unplug and then replug in your Arduino and then Open Firefly_Firmata
Follow the instructions in the file…
- Plug Arduino boards into your USB port; confirm that your Arduino’s green power LED in on
- Select your specific Arduino Board and Serial Port (Tools > Board; Tools > Serial Port) *Take note of your Serial Port COM #
- Verify (play button) and Upload (upload button) this program to your Arduino, close the Arduino program
- then open … Rhino/Grasshopper/Firefly (In our case Revit/Dynamo)
Upload the sketch…
