UART of XBee S2 module with intermittences

I have programmed a XBee S2 module with XB24-ZB ZIGBEE END DEVICE API 29A7 firmware and this module was with intermittences on UART.
With the XB24-ZB ZIGBEE COORDINATOR API firmware was evething OK!
Help me please! Because I need the ZIGBEE END DEVICE API to communicate with ZIGBEE COODINATOR API.
Thank you!

Hello Adelino,

That’s normal behavior, EndDevices sleep periodically by default when they are connected (see module’s user manual). If you want to wake up it to communicate with X-CTU you may press commissioning button (DIO1/SW3 in XBIB boards) once, the module will wake up for 30 seconds. When module is sleeping, it doesn’t listen to the UART, the On/~Sleep and/or CTS lines should be checked before sending anything.