I have project to send API packet (ZigBee Transmit Request, API Identifier Value: 0x10) to the coordinator without using (X_CTU), all the xbees are set up in API mode. I have installed the end device which is connected to the microcontroller ATMEL 89c52 as a (ZIGBEE END DEVICE API) & the coordinator which is connected to the PC-hyper terminal (ZIGBEE COORDINATOR API), and I can send (packet data) from end device to coordinator but cannot see it come out of the UART. My question is :(I know when talking to API modules via XCTU, the "Enable API" box must be checked on the PC Settings tab) but in my case ,Im talking to API modules via microcontroller (how can I enable the API (like X_CUT ), I cannot use( +++ & ATAP1) in this mode. Im sure data is being successfully sent (led indicator is glow when send data).I want to use API because I want to be able to know the destination & other info that data is coming from.your help is greatly appreciated.