ZigBee / XBee issues with Firmata

I'm just starting with attempting to communicate to the Arduino trough a simple Xbee network.

Everything actually works pretty well. I followed the tutorial at: blog.kevinhoyt.org/wp-content/xbee-setup.pdf to get the Xbee comm going and all seemed OK.

I'm using Firmata "out of the box" to test some basic I/O comm with my Arduino and it works OK. The problem is that when sending commands to the Arduino there can sometimes be some sort of breakdown or buffer overrun or something.

An example may explain this best:

1) Power everything up, see that the Arduino – Xbee – Xbee – PC communication is working 2) Using Firmata command protocol send/receive data from the PC 3) Set some Arduino AI pins to report – the data are received by the PC over the XBee network fine and can be processed (I'm using a PC with LabVIEW to view everything). 4) Set an Arduino Pin to be Digital out – I have this hooked to an LED to observe 5) Send the Firmata command to turn this LED on 6) Send the Firmata command to turn this LED off 7) Repeat the ON/OFF commands a few times relatively quickly (like a few mouse clicks) 8) The first few ON/OFF are observed with the LED, then there is a breakdown and the commands are not getting through 9) Once I observe that the ON/OFF commands stop being reflected with the LED, the Arduino appears to restart itself! 10) Bummer :(

This does NOT happen if the Arduino is connected directly to the PC (i.e. w/o the Xbee chain).

To me this seems like the data are getting bottled up somehow with the Xbee or with Firmata and then these build up to a problem!

Any suggestions much appreciated.