For a project i'm curently working on I need to wireless control an arduino and four differenty located relays. Controlling the arduino i allready managed using xbees. Now i am wondering wheter it would be possible to use xbees to create a network to also control the relays without using additional arduino's. So the sending xbee is connected to an arduino and the four relays are only connected to an xbee.
The XBees can be used to directly read and write digital and analog data, so, yes, you can use the XBee to directly turn the relay on or off, without a XBee.
Are you using series 1 or series 2 xbees. That type of direct I/O manipulation is a lot easier with series 1. With series 2 you need to get into the API command structure. But it is very possible without arduinos at each node.
Digi's site has all the information needed to configure the XBee to send and/or receive data using the digital and analog pins on the XBee to get/set sensor data.
I have never needed to do this, so I can't help you. I've read all the threads on the forum dealing with XBees, and I know that people are successful at using the XBees this way.
The walkthrough is semi-specific to remote controlling an Arduino, but it does show the key steps for setting up passing digital line status on an Xbee: (1) setting the state of the Digital IO lines (DIO), (2) the DIO change detect bit mask, and (3) setting the I/O line passing input address. (The last step is very important.)
I'm in the middle of a project that leverages this capability, and I'm now setting up an Arduino to send API commands which controls these IO pins remotely. (Which is basically what you want to do as well).
Feel free to post follow-up questions here and I'll do my best to answer them.
I am using Xbee series 1.
I took a look at ladyada's instructions. If I understand correctly it could work like following: on the transmitting Xbee i need to set the DIO pins to output (i.e. 3,4,5,6). On all receveir Xbees the I/O line passing should be set to FFFF. Next on xbee 2 DIO-3 should be set to input, on xbee 3 DIO-4 should be set to input, etc.