What are realistic data rates on XBEE wifi S6B?

XBee & XBee Gateway XBee - WiFi
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1

I would like to send two bytes of data at 5.8kHz. Without overhead I calculate this would be 93kbps. Unfortunately I’m getting significant package dropping at much lower frequencies and as I increase the frequency of the data transfer it gets worse.

Currently I have two XBEE Wifi S6B modules chatting to each other over an AdHoc Network. One is connected to XCTU and the other is connected over UART to a Teensy 3.1 (which is similar to an Arduino, uses the same IDE but has a Cortex M4 processor which runs at 72MHz). The current test I’m doing is getting the Teensy processor to write 10 bytes of data at 10ms to the XBEE module (~8000bps). Its currently connected via the UART pins which I believe should be able to cope with 1Mbps. The two XBEEs are set-up in Transparent Mode. The baud rate has been tested at both 115200 and 921600. I believe the XBEE Wifi S6 units are capable of communicating at between 1 and 72Mbps.

Both units have the latest firmware (2026) and I’m using the latest version of XCTU (downloaded on Friday). The XBEE units are communicating over less than 10cm. The environment is not electrically noisy and I’m measuring somewhere between -20dBm and -30dBm signal strength. Nothing else is communicating on channel A in the local area. I’m receiving fewer than 94% of the packages at the XCTU terminal. I’ve also conducted a similar tests with similar results with both XBEE units connected to XCTU but I removed one onto the Arduino to reduce the serial bus demand on my computer. However it didn’t make a difference.

How could I improve the data transmission rates with a higher success rate?

2

The serial throughput of the XBee WIFI module is documented at up to 320Kbps with the SPI port supporting up to 1MB.

(http://ftp1.digi.com/support/documentation/90002180.pdf Page 8)

If you are having issues with throughput, I would suggest switching to UDP instead of TCP for the protocol.

3

Thanks for pointing out the throughput on XBEE module but I’m already way below the limit plus I’m already using UDP not TCP. Is there anything else it could be?

4

which pins are you working with?
Are you able to reproduce the issue using XCTU?

5

I’m using an XBEE Adapter (http://www.hobbytronics.co.uk/xbee-usb-adapter?keyword=xbee) to connect the XBEE to my computer (when needed) and the adapter is plugged into a breadboard to make the connections to the Teensy. I’m connecting pins 3 & 4 on the adapter which correspond to pins 2 and 3 on the XBEE which are Tx and Rx. The schematic is given on this webpage: http://www.hobbytronics.co.uk/datasheets/ht/xbee_usb_adapter.pdf.

I have already tried using XCTU for both XBEES with no Arduino/Teensy in the loop and I have the same issue of having really low data rates.

6

You may want to try downgrading the firmware to 2024. I have a VB program talking to the XBee thru Ethernet which uses transparent mode to send the data to a serial device. My older 2024 f/w modules work great with 200ms updates. I just got some new modules in with f/w 2026 and my data updates went to heck and took seconds to update. I downgraded these to 2024 and now they work.