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Why do i not receive the first x characters sent from test board to PC via Xbee S2 PRO?

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I have robot motherboard based on an atmel mcu and xbee s2 pro. (router)
I made another board for communicate to the PC, it is based on FTDI FT232RL. I use it with same xbee unit (coordinator).

I can receive any amount of data from the PC to the robot, but i have to send at least 45 characters from the robot to receive just one at the pc. So for instance i send 100 characters from the board, there is a little delay and i get only the last 56 characters. It has been monitored by several terminal programs.

The xbees are the same (zbp24-zb), one coordinator another router, same channel, same pan, newest firmware (coordinator 20A7, router 22A7), both AT mode. Serial paramteres: 9600 8N1.

Is there some special parameter i should change about the xbees, or the FTDI usb serial converter may be the guilty one? I set the serial port to make hardware flow control and with xon/xoff but did not help. And i did the optimization according to this: http://www.digi.com/support/kbase/kbaseresultdetl?id=3418

I would appreciate any help or idea!
Wish the best!
asked Nov 14, 2014 in XCTU by Gela90 New to the Community (0 points)

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1 Answer

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Other than setting the DL and DH of one to match the SL and SH of the other, that is about it. What I would suggest is removing the radios from your application and just connect the two with cables to get it working. Once you have it working, then add in the radios.
answered Nov 14, 2014 by mvut Veteran of the Digi Community (15,323 points)
Thank you, mvut!

I was debugging all day, watched the signal coming out the Dout pin of the coordinator (pc connected) xbee via oscilliscope, and i noticed, that the frst character is the one i saw on XCTU terminal. Then i was sure that the problem is at my robot firmware and indeed i had not taken into account the time the router joining to the coordinator (i touched a led between pin gnd and DIO5, and it took 1-2 seconds before the blinking). So the first 44-45 characters could have not sent out because the router had not joined the PAN yet.

Anyway thank you the metod you write down above!