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TX/RX packet lost

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Dear all,
I have got the following issue using two ProS1.
both configured at 9600bps, transparent mode, No ACK, 16bit addressing, peer to peer and connected to two micros.
the first (master) sends a 3chars packet each 100ms.
the second (slave) receives.
if I put the oscilloscope with track 1 on the TX of the Master and track 2 on the RX of the slave I noticed that randomly, for some second, the RX packets are lost and absolutely not synchronized with the TXs. sometime, this lack of receiving may reach 1s. after a while, everything returns normal.
I tried many things and also read every where but I did not find yet the matter of this behavior.
any suggestion?
BTW, I also checked the power supply as well as reset line.
I'll really appreciate any kind of help.
regards.
asked Dec 28, 2016 in IEEE 802.15.4 by aa.defilippo New to the Community (0 points)

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1 Answer

0 votes
What firmware version are you working with?

What is your MY, DL and DH of each radio?
answered Dec 28, 2016 by mvut Veteran of the Digi Community (11,392 points)
Hi mvut, thanks fo reply.
I am not at the Office at this time but I Can guarantee that the fw version is the last allowed by XTC for that module.
DH is 0. DL and MY are 2 and 3 swapped.The communication runs normally for 1 or 2 minutes. Suddenly the RX signal disappears to be back again after some second. I tried several modules with same result. Only changing to a couple of pro s2b is a little better but the problem is still present.
I am quite sure that if you try the same configuration you will face it.
Try changing the channel you are operating on. I have streamed large amounts of data (Megs) at 115.2kbps without having this issue or at least having a few re-transmissions occurring.  Also make sure that you are using Hardware flow control and a good interface board such as the XBIB-U to work from.
Hi,
here I am after some more test.
first of all I apologize for the wrong information about the second kind of module I tested: it is a XBee S2C and not B as I wrote before.
Anyway, I tried, as you suggested, with different channels but "the song remains the same".
I also tested with a PC instead of a microcontroller because I also supposed that maybe the baudrate could be not enough accurate, but no better results.
changed the baud rate to different values, until 115.2K but nothing.

Finally, the only affordable solution (with only a few lost frames) was to insert a 10ms delay between the reception of the frame by the slave and its response to the master. I tried this because I supposed there should be a kind of timeout to respect by the radio hw before switching the antenna from rx to tx and viceversa. I also had to add a randomized delay to the transmission of the request because when you have more then a pair operating on the same channel there is ALWAYS a lost frame on the receiver side. with this delay I eventually reduced the synchrnisation among the transmitters.

so, at the end this is my configuration:
the Xbee has everything in default but:
- DH, DL and MY as per my previous comment.
- 19200bps and 802.15.4 no ACK.
- Channel 17 or 1A

Please, let me know your opinion and idea about this because I lost a large amount of time before finding an affordable setup.
Ok, tomorrow I'll try. I hope to come back with good news. Thanks a lot.
That looks like the same thing I was telling you to do.
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