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

XBee & XBee Gateway XCTU
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1

Hi!

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!

2

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.

3

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!