Reply To: Optical dissolved oxygen solutions?

@madbird – I’m sorry, I’m not at all familiar with the MKR or any of its shields.  For anything to work, you need to know what kind of serial port you need and how the pins are connected.  Merely creating and not using an AltSoftSerial instance shouldn’t be a problem at all.  But, of course, nothing’s going to work if you don’t tell the code the real port the device is connected to.