Andrew,

Very many thanks for such a prompt reply. I can report seeming success
after several hours work.

I have 4 x XBee Pro 868 radios. XBP08-DP is the modem identifier with the
latest firmware 1061 installed using X-CTU. I chose the default Function
Set, XBEE-PRO 868 SINGLE CHANNEL.

I was able to configure them to API ENABLE mode 2 with the command ATAP 2
in a terminal window. One radio is set as COORDINATOR with ATCE 1 and the
others as STANDARD NODE or END DEVICE with ATCE 0 or ATCE 2. I gave each of
them a different name with ATNI END DEVICE 02, for example. They each have
the same Modem VID with ATID 3001, in my case. I also set the same baud
rate for serial i/o, ATBD 5 for 38400 for convenience in connecting each
radio to my PC for analysis.

Finally, following a warning on the paparazzi VAU project page, I reduced
the output power to 1mW because these are long range radios close together
in a small room, my lab, with ATPL 0 and saved my new setting with ATWR.

I powered up each radio and connected the COORDINATOR radio via USB to my
PC and the X-CTU software. In PC Settings, I set the baud rate to 38400,
Enabled API and Use Escape Characters. Next I opened the Remote
Configuration (NETWORK) window under Modem Configuration, clicked Open Comm
Port and then Discover. All the radios, with their hardware address and
IDs, appeared one by one within a few seconds.

So far so good. I repeated the X-CTU process with each radio in turn. Those
configured as END DEVICE or ROUTER listed the other END DEVICEs and ROUTERs
in their NETWORK window but not the COORDINATOR radio which only appeared
in its own NETWORK window.

However, I tried the X-CTU Terminal Window to see if I could send a simple
text message from one radio to another radio connected to X-CTU on
different PC. I tried typing in the window and sending a randomly assembled
packet but to no avail. Nothing appears in the other PC Terminal windows.
This does not entirely surprise me. It is pretty much the standard test in
AT mode but API mode is packet based and other radios will only respond to
valid packets.

Any ideas on how I can easily test API mode further?