Home/Support/Support Forum/xBee Modules S2: Want to send quick messages to all endpoints - how to fix / avoid the slow unicasts ?

xBee Modules S2: Want to send quick messages to all endpoints - how to fix / avoid the slow unicasts ?

0 votes
I've got three Arduinos connected to XBee S2 modules (one Coordinator and two Endpoints), all running API mode. The firmware is 1120 / 1320.

How can I stream data really fast from the coordinator to the two endpoints ? I am trying to make the endpoints respond to live audio. The data sent to them is about 10 bytes of payload - which is the output from an FFT; but the endpoints need to respond close to real time, thus the data transfer rate from the Coordinator needs to be as fast as possible. I do not expect the Endpoints to send any data back.

I tried the following, and ran into these issues:

1. Asynchronously sending (ie: without waiting for a response from the module when sending) unicast messages from the Coordinator to only one Endpoint (call it E1). This works quite fast, regardless of whether the other endpoint is on or off, and I would like to maintain this speed. However, I can't maintain this speed when sending to both endpoints (see below).

2. Asynchronously sending one unicast message from the Coordinator to one Endpoint E1, then another unicast message from the Coordinator to the other Endpoint E2. When this happens, E1 receives the data very slowly (about 1 message every second). This slowness happens regardless of whether E2 is powered on or off.

3. Asynchronously sending broadcast messages from the Coordinator. When this happens, E1 receives the data very slowly (about 1 message every second). This slowness happens regardless of whether E2 is powered on or off.


Why is this happening, and more importantly how can I make the Coordinator send data to both Endpoints really fast ?

Thank you !

PS: In case it matters - the modules are wired only on pins: VCC,GND, DIN,DOUT, and ASSOC. The modules respond well to API AT commands. I've also tried changing BH to 1, without any effect on the latency.
asked Dec 8, 2015 in ZigBee PRO Featureset (and legacy ZNet 2.5) by julesra New to the Community (0 points)
edited Dec 8, 2015 by julesra

Please log in or register to answer this question.

3 Answers

+1 vote
First off, the firmware version you are working with is the Znet 2.5 code that has not been supported by anyone for almost 6 years. Next, the Zigbee protocol which the XBee ZB modules you are working with is not designed to stream Live data to more than one module. Never the less without some sort of delay. For that it is best to use the XBee 802.15.4 modules instead.
answered Dec 8, 2015 by mvut Veteran of the Digi Community (11,298 points)
0 votes
Asynchronously sending one unicast message from the Coordinator to one Endpoint E1, then another unicast message from the Coordinator to the other Endpoint E2. When this happens, E1 receives the data very slowly (about 1 message every second). This slowness happens regardless of whether E2 is powered on or off.


___________
NOOR
answered Dec 10, 2015 by hnoor0011 New to the Community (1 point)
0 votes
Asynchronously sending broadcast messages from the Coordinator. When this happens, E1 receives the data very slowly (about 1 message every second). This slowness happens regardless of whether E2 is powered on or off.


_____________
NOOR
answered Jan 11, 2016 by hnoor77 New to the Community (1 point)
That is correct.  You are limited to about one broadcast transmission per every 2 - 4 seconds.
...