Xbee S2 Throughput

XBee & XBee Gateway XBee - Zigbee
1

Hi. I am sending Hello World (11 bytes) from my coordinator to End device which replies with “ACK” packet. Both the Xbees are using Arduino for computation. My round trip time according to Arduino comes as an average of 54ms at almost zero distance. According to this i am getting throughput of 1.63kbps.

(Throughput = bits /round trip time) if i am correct then.

The power level is at maximum of 2mw with wire antenna. Can anyone please advise if this is correct or too low?

Are there any other methods which i can use to analyze the data throughput of Xbee and round trip time? I would really appreciate if anyone can emphasis on this please.
The codes that i am using are as follows:
Transmitter Xbee

unsigned long startTime;
unsigned long RoundTripTime;

void setup() {

Serial.begin(9600);
}

void loop()
{

//startTime = micros();
Serial.print(“Hello World”);
startTime = micros();

while(!Serial.available()){}
char bdata;
String data = “”;

while(Serial.available() > 0)
{
bdata = Serial.read();
data += bdata;
delayMicroseconds(1050);
}

if(data == “ACK”)
{

 RoundTripTime = micros() - startTime;
 //Serial.println("Total time: ");
 Serial.println(RoundTripTime);

}

delay(2000); // prevents overwhelming the serial port
}

Receiver Xbee
void setup()
{
Serial.begin(9600);
}

void loop()
{
// listen out for the letter “H”, and send a “K” if we get one.
while(!Serial.available()){}

char bdata;
String data = “”;

while(Serial.available() > 0)
{
bdata = Serial.read();
data += bdata;
//delay(2);
delayMicroseconds(1050);
}

//Serial.println(data);

if(data == “Hello World”)
//{
Serial.print(“ACK”);

//delay(1000);
}

Thanks in advance.

2

Yes, if you have an end-device, then it only polls the parent (your coordinator) periodically. So I’m surprised you are seeing 50 msec instead of 100+msec.

Anyway, it can be a complex dynamic, and if you really worry about throughput you perhaps shouldn’t be using a transaction-oriented protocol like ZigBee. ZigBee is designed to (for example) check a thermostat temperature every few seconds, so ‘throughput’ has no relevance.

You’ll find non-mesh radio like pure 802.15.4 (Xbee S1) much ‘faster’ from a throughput stand-point.

3

Thanks lynnl. You have cleared my doubts.