SparkFun Forums

[Joeisi]

This will work but you are better off doing pairing. Basically this means that all the radios in your system have the same address and broadcast to each other. On the plus side, any two radios will talk to each other right out of the box. On the downside, with more than two radios, you have no idea where your 'ack' messages are coming from.

Solved by hardware addressing to some extent.

[alkaser2100]

This will work but you are better off doing pairing. Basically this means that all the radios in your system have the same address and broadcast to each other. On the plus side, any two radios will talk to each other right out of the box. On the downside, with more than two radios, you have no idea where your 'ack' messages are coming from.

I checked out the xbee datasheet, and I found that the default mode is unicast with short16 bit addressing but I'm not shure due MY,DL and DH are zeros ( I read them using x-ctu). also, I do not what you mean with the pairing and what the available alternative of pairing if it was the default method???

Solved by hardware addressing to some extent.

what do you mean with hardware addressing in xbees. I used two xbee modules to communicate between MATLAB and PIC serially and vice versa. so, do you think that the addressing mode is the reason of my xbee's probem???

thanks

[Joeisi]

Shoot I meant software. Im sorry I cannot type....

[alkaser2100]

no problem my friend, do you mean I should change the address of both xbees manually via x-ctu?? this is my first time with xbee. I thought that I can operate them easily by changing the baud rate only and I succeeded but with the signal losing problem . but now, I think that I should change a lot of things e.g. the address of xbee module!!!

[stevech]

I'm using the default addressing. I did not change the addressing mode nor any one of addressing registers. however, when I read the addressing registers, I found MY=0. DH=0, DL=0. is this good???

Need to read up before taking the beast out of the hanger.

[Joeisi]

Well If you would give all the recivers the same address, you could send one package of the transmission as a constant address.

[stevech]

Note that 802.15.4 has a broadcast address (0xFFFF) much like IP and ethernet have the same. There's no ACK of course.
The term "broadcast" in networking means using that all 1's address to do one-to-many. In wireless, it goes to all in-range devices on the same channel and same network ID (PAN ID, like SSID in WiFi). There is an all 1's broadcast PAN-ID too, but that's really not good to use!

The 16 bit short addresses are messy if you don't use a network layer (ZigBee, ISA100.11, 6LowPAN) atop the 802.15.4 MAC and PHY. Without a network layer, it's best to use the 64 bit addressing - because every module has a unique 64 bit address, much as do Ethernet NICs with 48 bit addresses.

[alkaser2100]

Thank you Joeisi and stevech,
I chenged (MY) of first xbee to 1 and its (DL) to 2 and (MY) of second xbee to 2 and its (DL) to 1 that means short 16- bit unicast addressing. moreover, I increased (RR) retries but it did not work too where the problem still exists
let's think about together: :think:
- is usually the signal between two xbee modules lost when any one of them is moved? is this normal:?:
-if No, what is the reason for this losing???
-- is it the power source? ( I checked the voltage of both the 9.6V battery and voltage regulator and there was not any drop while losing)
-- is it the addressing mode? ( i'm using 16 bit unicast and I,m going to try 64-bit unicast)
anything else???
- if Yes,
-- is there a failure in one or both xbee modules??

[stevech]

XBee series 1 non-Pro model? It's about 2mW. Range depends on antenna types. Worst, it should be 100++ ft line of sight.
Xbee series 1 Pro model - is 60mW. Range again depends on antenna types. Expect 300-1000 ft line of sight.
With gain antennas, 1/2 mile or more line of sight.
Moving with the radius affects nothing, as long as serious RF obstructions aren't present.
At close range (say, 50 ft) all sorts of non-line-of-sight should work.
You can look at the received signal strength (RSSI) with XCTU or your own software to query that register via an AT command or via use of the XBee binary API (there are Arduino and other libraries for that API).

Be sure to read, re-read, re-re-read the XBee OEM manual.

[alkaser2100]

the problem in RSSI that it is not available without or before sending or receiving data. additionally, I want to reduce the required time to send or receive data in order to decrease the response time of my controller.
I tried my program outdoor but it did not work even I put xbee modules faced to each other, it seems like there is no signal at all although I tried the same program at indoor place an it worked bat at small range.
do you know what the reason for this problem? do you that there is a malfunction in my xbee modules??

[stevech]

I can only say that with XBee non-Pro models (2mW, lower than the Pro model)... range of course is affected by what kind of antenna you chose. The chip antenna (blue thing on PC board) is a poor antenna and is directional as said earlier.

RSSI is that of the last-received packet.

If you cannot exchange messages at 50 ft. or so, there's a fundamental problem.
Use the XCTU range test program to eliminate the chance that part or all of the problem is your configuration settings.

A zillion people use these products quite successfully.
It takes some reading of the OEM manual and some learning about communications. It's not a simple appliance.