With the rSoftwareSerial library you can turn regular pins to serial ports. This is useful as the hardware serial is used by the IDE during development.
There are some limitations to the supported pins: https://www.arduino.cc/en/Reference/softwareSerial
As an example, the following program should run on two boards. When you press on the connected button, the on-board led on the other board will turn on.
Sub Process_Globals Public Serial1 As Serial Private astream As AsyncStreams Private led13 As Pin Private btn As Pin Private softserial As SoftwareSerial End Sub Private Sub AppStart Serial1.Initialize(115200) Log("appstart") led13.Initialize(13, led13.MODE_OUTPUT) led13.DigitalWrite(False) softserial.Initialize(57600, 10, 11) astream.Initialize(softserial.Stream, "astream_newdata", Null) btn.Initialize(btn.A0, btn.MODE_INPUT_PULLUP) btn.AddListener("Btn_StateChanged") End Sub Sub Btn_StateChanged (State As Boolean) Dim b As Byte If State Then b = 1 Else b = 0 astream.Write(Array As Byte(b)) End Sub Sub astream_NewData (Buffer() As Byte) Dim state As Boolean = Buffer(0) = 1 'state will be true if buffer(0) is 1. led13.DigitalWrite(Not(state)) End Sub
The library is attached (it will be included in the next update).