I’ve been working with S1 XBees for some time now, investigating firmware settings and understanding the API mode packet structure. I am a software developer and new to electronics.
I have 9 XBees set up as endpoints and one as a coordinator. I have a program running on the computer hooked up to the coordinator that sends a IO sample request to each XBee endpoint in turn, pausing between each request and pausing for 10 minutes when all 9 requests have been sent.
Unfortunately, for every 9 requests sent, 2-4 of them get a NO_RESPONSE response from the coordinator. It’s not always the same endpoint that can’t be reached, and an endpoint that didn’t respond in one set of 9 requests may respond in the next set of 9.
Does anyone know why this might be? All endpoints are set to never sleep - and sleeping is the only logical reason I can think of that an endpoint would only respond sometimes. I’ve been chewing through this problem for three months without any real successes.
My first thought is a bad connection or several bad connections somewhere in the network. But you say it is a different endpoint point from time to time. However, I would not rule out a bad connection. If you have this option, I would try and disconnect an endpoint one at a time and see if the problem continues. If it continues, there could be more than one problem connection. Therefore, I would divide and conquer by dividing the network in half or thirds.
I have not worked with xbees at all, but I have alot of experience with networking control equipment. In my experience, 9 times out of 10, it’s hardware - especially using serial and coaxial cabling.
Thanks for the input. The traces on the circuit boards seem to be fine and all components are seated well. I’ve just concluded a four-week test wherein the error rate was 0.15%. The difference is that in this most recent test, the coordinator and all endpoint XBees were all in an area of about a square foot. Previously there was about three feet of space between the coordinator and the endpoints. Changing the power level made no difference.
It appears the XBees have a problem consistently communicating across any distance. I am still trying to determine why 0.15% of the time these units are unable to communicate when they’re right next to each other.