XBee unstable sensor data transmission

Question

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 <SoftwareSerial.h>
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?

Answer 1

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.