Hi,
At the end, in order to figure out all the weridnesses regarding the apparently different behavior of the Arduino on different platforms, I only need to answer a simple question, well two simple questions:
every time it accepts a connection on the serial port, or only when it is powered up or reset?
send in Pd to the [arduino] object) supposed/expected to cause the arduino to reset?
This is slightly OT but it is relevant for working with [arduino] in Pd.
Thanks m.