I’m starting using Xbee modules for a project. I’m try to setting a Point-Multipoint Network, but I’m having a couple of problems!
First at all, I have a XBee Pro S2 module and I’m setting it has Coordinator AT in broadcast mode, I have two more modules but those are Xbee S2, I’m setting those has routers AT and they are sending data to the coordinator, The coordinator is receiving all data, but when the coordinador is sending data to routers modules they are losing data and there is a moment (after sending about 3 package of 20 ASCII characters) when routers stop receiving data, after a few seconds in one of them the data arrive, but in the other its lose. Any idea why it’s happening?
I’m trying to change the features of the modules but always I have the same result. I thought that could be the USB port of my PC, but I plugged one router on a laptop and it happens again.
Its any way to set the modules has a virtual cable? I need to send a digital signal by Coordinator to routers, and from routers send a response signal to Coordinator, how can I avoid the data shock?
I’m attaching 3 images, in the first one is the modules settings, in second one is the coordinator to routers problem, and in third is how the coordinador doesn’t lost data.
I really would appreciate if anybody could help me with this problem! Thank You soo much!! (And sorry for my english!!!)
First of all, I noticed that you are not using the latest firmware, download the new versions and try again.
Second, how much do you wait between each broadcast send? One second? as fast as you can…? Does it reproduce when you do a unicast to the routers? (DH & DL set to the module’s SH & SL)
Finally and not very important: if the routers will always send data to the coordinator you can set DH&DL to 00 instead of the coordinator MAC address.
Thank you so much for your answer. The first I did was the firmware update, after that I did a test again but I get the same result. I made the data send almost the fast as possible, and after a few seconds is when happens the data loss on routers. I did set a couple of zigbee modules in unicast mode and there is not data loss. I made also the last test you recommend but the result is same. I have read that in broadcast mode there may be a kind of lag, but there may be a way to avoid or al least reduce it. Any other idea will be good received!!!
ZigBee (the Xbee ZB/S2) doesn’t support broadcast this way, so you cannot reasonably set your coordinator’s DH/DL to FFFF unless you delay at least 5 seconds before your slaves respond & 5 seconds before the next data going out.
If you want point-to-multipoint, use the S1 or raw 802.15.4 Xbee.
Thank you so much for your answer! I check the features of S1 and this serie could work better on this kind of network settings! I made some other tests changing the modules settings (as disable the CTS, or the reducing the hops…), but there was always data loss. One more question… Do you know if with S1 can I also make a network where all the modules make broadcast to all others modules?
Thank you Again!!!
If you do NOT need the mesh, you’ll be very happy with the S1. I think more Digi customers use S1 than S2 and gives you VERY predictable time-latency in the 50msec range! So literally, your central units sends the broadcast and in 10-50msec, the remotes see it. They answer and 10-50msec later the central unit sees the response. of course need to add in the serial UART shift latency.
S2/Zigbee offers nothing so speedy, as route discovery and the broadcast random back-offs mean ANY data can be delayed up to 5 seconds at any time.