XBee unstable sensor data transmission I am using two XBee Series 2 modules (Zigbee), an Arduino Uno, and a HC-SR04 Ultrasonic sensor to send distance readings from the coordinator XBee on the Arduino to the XBee connected to my computer. I configured the ArduinoXBee as "Zigbee coordinator AT" and the ComputerXBee as "Zigbee end device AT" with the following networking settings:

Coordinator:
PanID: 1234
DH: 0
DL: FFFF 

End Device:
PanID: 1234
DH: 0
DL: 0 (so it can only talk to the coordinator) 

The problem I am facing is that when I open the End Device terminal on X-CTU, the distance readings I get are accurate yet very unstable. Like it receives the correct readings but the transmission is unsynchronized as it sometimes receives 5 numbers in one transmission and lags for 10 seconds then receives the next bunch and lags for another 10 seconds and so on... 

The arduino code is:

#include &lt;SoftwareSerial.h&gt;
const int trigPin = 13;
const int echoPin = 9;

SoftwareSerial xbee(10, 11); // RX, TX

void setup()  {
   xbee.begin( 9600 );
   pinMode(trigPin, OUTPUT);
   pinMode(echoPin, INPUT);
}
void loop()  {
long duration, distance;
  digitalWrite(trigPin, LOW);  
  delayMicroseconds(2);
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10); 
  digitalWrite(trigPin, LOW);
  duration = pulseIn(echoPin, HIGH);
  distance = (duration/2) / 29.1;
  xbee.println( distance );
  delay(500);
}


Can anyone help me?
Probably the end device is set into sleep mode. Check the Sleep Mode(SM) and the sleep period(SP) because what I can see is the XBee gives readings for every 10 seconds.