XBee Series 2 w/ Arduino Nano Communication Issues

Hi all,

I'm having a few issues getting a pair of XBee S2 modules talking to each other properly. One XBee is connected to a USB explorer plugged into the computer and the other is connected to an Arduino Nano. The 5V logic from the Arduino Nano is stepped down to the 3.3V logic that the XBee runs at (and vice versa) using GTL2002 2-bit bidirectional low voltage translator (www.nxp.com/documents/data_sheet/GTL2002.pdf). Both the Arduino Nano and the XBee are run off independent power (currently a breadboard at 5V with a regular for 3.3V).

If I use the following software and send characters from the PC to the Arduino over the XBee link (through the terminal), it works correctly. The Nano's LED lights up whenever a key is pressed.

int incomingByte = 0;   // for incoming serial data
int led = 13;

void setup() {
        Serial.begin(9600);     // opens serial port, sets data rate to 9600 bps
        pinMode(led, OUTPUT);
}

void loop() {
        
        // send data only when you receive data:
        if (Serial.available() > 0) {
                // read the incoming byte:
                incomingByte = Serial.read();

                digitalWrite(led, HIGH);
                delay(1000);
                digitalWrite(led, LOW);
                delay(1000);
        }
}

However if I try and transmit any information from the Nano to the computer, (see code below), the terminal program on my computer connected to the XBee receives no message. I can see serial messages down the wire that is connected to the Din on the XBee using an oscilloscope.

void setup()
{
  // start serial port at 9600 bps:
  Serial.begin(9600);
}

void loop()
{
  // if we get a valid byte, read analog ins:
  Serial.println('0');
  delay(2000);
  Serial.println('1');
  delay(2000);
}

The XBee connected to the PC is configured as a ZigBee Coordinator AT mode radio, and at the arduino mode a ZigBee Router/End Device AT mode radio. Neither radio has flow control enabled. The radios do work together otherwise. Any ideas?