Following this post are several (about seven) threads that document some things that I have noticed about the XBee-Pro 900 when used in API mode. There don’t seem to be very many threads in this forum. Hopefully that will change as it seems like a very useful radio, at least for my application.
My application is telemetry (and possibly control) in a model aircraft. Using the XBee in Transparent Mode is very very simple, and I would have stopped there if I hadn’t decided to explore its use for control as well.
When used a control link, integrity of transmission becomes paramount. And in API mode, it seemed that there are very adequate provisions for assuring that a transmission has succeeded. I hoped as well that there would be indications (increase in Retry Count) of nearing a range limit. Therefore, I embarked on utilizing the API mode of the radio to gain access to the extra information in a systematic manner. I have been somewhat thwarted in this endeavor as it appears that the reported Retry Counts do NOT act as expected. In addition, RSSI does not seem to available. I am hopeful that the TR count (transmission errors) will give an indication of an approaching range limit, although I was hoping to detect the range limit approaching before packet transmissions started failing completely.
This is a very interesting series of posts regarding your experiences and model airplane application. I’ve never hobbied with model airplanes, but I’ll bet adding an XBee-PRO to a high powered rocket could gather some interesting data as well, or at the very least work as a homing device when the bird floats down to earth. Thankyou
Hi BobA,
I am doing the same thing, sending telemetry from my plane back to my base station. One thing that is occuring is that if I get out of range, or hit an error where the transmission fails, I am having issues when I get back in range, that being that transmission fails. I have tested this on the ground transmitting location etc as I move around. Block the signal with a large building, then come back into radio contact and none of the transmissions from that point on make it back to the base. I can recieve however.
So basically looking for any pointers on how to handle transmission errors in code.
I am writing in C# and listen for the serialErrorRecievedEventHandler. Basically all I have been doing within this event is to discardOutBuffer and and discardInBuffer. This doesn’t really seem to be the solution. Any pointers would be much appreciated.
A couple of other questions associated with this post.
1: Can anyone please point me at a good resource for serial port communication?
2: what is the best way to handle large packets of information transmission where the size of the data is larger than that which can fit within the TX / RX buffers. Eg. an image.
Lastly, Digi, these units are so much better than I was hoping for, simply brilliant. My many thanks.
