XBee Series 1 not working well at 115200 baud

XBee & XBee Gateway XBee - 802.15.4
1

I’ve written a short test program in C to benchmark a network between several XBee Series 1 radios mounted on USB development boards. For now, I’ve set up one radio as a coordinator and set the other radio to associate to it. Using API mode, I’m trying to send messages from the end node to the coordinator. This works well for baud rates up to 57600 but at 115200 most of the API messages to the radio are not received successfully. I’m guessing that the API message is getting corrupted since when a message is sent to the radio successfully I receive a TX Status packet back. When the message is not received, I get no response back and the message is never transmitted across the network. I’ve tried experimenting with the RO value with no success. I’m working with Fedora Core 6 and 9, firmware 1084 on my radios. The same host machines with the same development boards work fine at 115200 baud with Series 2 radios oddly enough.

If anyone has any suggestions on how to make communication with the Series 1 radio at 115200 baud more reliable or how to go about diagnosing the problem further, I’d greatly appreciate it. Unfortunately, I’m looking for data rates greater than 57600 so 115200 baud is a necessity for me.

Thanks!
Tim
tsorrent at bbn dot com

2

If anyone else runs into this - I got a tip from Digi to interface with the XBee with two stop bits rather than one. Works great now! Other suggestions were to open the PC’s com port at 112kbps rather than the full 115.2kbps or interface with the radio at a lower baud rate.

3

Yes, I discovered this the hard way. It appears as though the XBee will keep up for a while, but after you send 50 to 100 bytes, it will randomly drop a portion of the bytes. Unfortunately, the XBee does not appear to have enough CPU cycles to run the hardware handshaking lines either in this situstion.

4

Thank you tsorrent.I was thinking hopelessly for the same problem.2 stop bits is great.Works fine now.
Thanks again.
Cheers.

5

I’ve found that using 111111 baud with 1 stop bit works reliably. This rate can often be got on MCUs using a ‘round’ clock like 8MHz (111111=1MHz/9)

6

Hi mike
Thank you for your advice.
Could you please let me know you have ever checked error rate with 111.111 baud speed?
Best regards
volkan

7

Which side is set to use 111111 Baud? The xbee, the uc or both?

Thanks, Jan