Unable to TX from COORDINATOR to END DEVICE

XBee & XBee Gateway XBee - Zigbee
1

Hello,

First time evaluating Zigbee ZB protocol, I have only had previous experience with the 802. protocol tranceivers, and I have a simple question that I just cannot find a direct answer.

The link I desire is between a ZIGBEE COORDINATOR AT and a ZIGBEE END DEVICE AT. Both modules I was able to program these firmwares using X-CTU to the most current version. In a nutshell, I can transmit from the END DEVICE to the COORDINATOR, but I am unable to transmit from the COORDINATOR to the END DEVICE.

PanID’s on both modules are set to “0x123”, and destination addresses (both L and H) are “0” on both modules. Network Security settings are left default. I understand that I am missing something with the Zigbee protocol, but I would really appreciate the fundamental behind the 2-way communication scheme, and how I can implement it.

One more things to add…right now, when I transmit from END DEVICE to COORDINATOR, the coordinator outputs a header from its UART port, as seen in the X-CTU terminal. I do see the data string at the end of this ~10 byte header, and what appears to be a checksum after the data string. Can I change this output behavior to only output the data string?

Thank-you!
Sean Michnowski

2

Hi,

Try setting DH and DL of End Device as SH and SL of Coordinator and vice versa. Then reset both the module. Remember, Start the coordinator first.

3

Hi shahrj1988,

I tried what you specified, but to no success. I also made sure I powered up the coordinator before I did the end device.

I tried reprogramming the end device to be a ‘ZIGBEE ROUTER AT’, thinking that might affect things; but communication is still unchanged…I can transmit router-to-coordinator, but not coordinator-to-router.

I appreciate your input, and I’ll certainly try anything else you specify.

4

OK, figured it out! Just completely reflashed the firmware on both modules, and started new. They can communicate fine.

So I guess I tried to set too many parameters at the same time.

Thanks for your help, I did use your advice when setting the DH and DL for both devices!

5

Also be aware that technically, a coordinator cannot ‘transmit’ to the end-device. The coordinator transmits the message to the PARENT of the end-device (which is likely the coordinator, so it just holds it), and the end-device polls the parent for data - by default 10 times a second.

So using an end-device which is awake makes your RF very noisy with pointless polls.

I hope you also know that end-device are not part of a ‘mesh’. Only routers (& the coordinator) participate in mesh/diverse path routing.