XBee init fail -5 and -62

Hi every one, I am currently programming with one coordinator(BL4S100) and several remote device(XBee Sensor Temperature\Light\Humidity , Xbee Digital I/O adapter…).

I am have a issue that when the device is ON(able to communicate), my program can run smoothly, however when one of the remote device is OFF( due to no power or out of range), I did not receive any error of unsuccessful message send to that device, instead the message which can not be send will queue up in the buffer and other message can not sent out, after a while my program stopped with error message xbee_init() fail -5(xbee timeout).

Is any one experience the same issue? how or what AT command can detect the remote device is not in the network? I dont want to use the node discovery every time before i sent any message out since this action is too time consuming.

Can I do it by observing the status of the CTS flow control pin on the XBee module of the BL4S100?