Losing communications

I’m new to XBee.

I have one XBee (Series 2) set up as a COORDINATOR AT. I have another XBee set up as an END DEVICE AT. I only want to use transparent mode so that my PC and my microprocessor think they’re communicating over a normal RS-232 line.

I want the coordinator to always send commands in broadcast mode because I intend to add three more end points when I get the first setup working. I set the destination address on the end point to the coordinator’s serial number(s). I’ve attached the files that show the setup of each in X-CTU.

This setup works momentarily: My PC will communicate with the microprocessor thru the XBees the same way that it would with a serial cable attached (I have a switch that toggles between hardwired and RF.

After a few moments, the communications end and I can’t even see the end point any longer with X-CTU. I have to hold down the commissioning button in order to read the XBee with X-CTU.

I assume that this means that the end point is very busy trying to do something and can’t be reached any longer. I’ve tried different modules with the same result. What am I doing wrong?