Imp Code

class Coordinate extends InputPort{
    type = "integer"
    name = "position"

    constructor(name){
    base.constructor(name)
    }

 function set(value) {
        server.show("X: "+value.x+", Y:  "+value.y+", Angle: "+value.z);
        server.log("X: "+value.x+", Y:  "+value.y+", Angle: "+value.z);
        hardware.uart57.write(value.x+","+value.y+","+value.z);
}
}

function initUart()
{
hardware.configure(UART_57); // Using UART on pins 5 and 7
hardware.uart57.configure(19200, 8, PARITY_NONE, 1, NO_CTSRTS);     //Setting up a channel between Arduino and EI
}

// UART polling function.
function pollUart()
{
imp.wakeup(0.001, pollUart.bindenv(this)); // schedule the next poll in 10us
local s = "";
local byte = hardware.uart57.read();

while(byte != -1) {
s+=byte.tochar();
byte = hardware.uart57.read();
server.log("reading byte");
}

if(s.len())server.show(s);
server.log(s);
}

// Executing the functions
imp.configure("RobotWireless", [Coordinate("Coordinates")], []);
initUart(); // Initialize the UART, called just once
pollUart(); // start the UART polling, this function continues to call itself

//NOTES: The "reading byte" string never shows up on the log.