In the previous tutorial, Zigbee technology and its application in building Wireless Sensor Networks was discussed. In this tutorial, learn to perform simple Client to Client Communication over Zigbee Protocol. There will be two Xbee modules taken and will be configured to communicate data with each other over the air.

The Xbee devices communicate with each other wirelessly over the air. They do not have any microcontroller or processor in themselves, so they cannot manage the received or sent data. They can simply transfer the information what they receive. But they can be interfaced with other microcontrollers and processors like Arduino, Raspberry Pi or PC via serial Interface.

So, basically, Xbee modules are capable of two types of communication – wireless communication and serial communication. The wireless communication takes place between Xbee devices so that the devices act as radio frequency (RF) devices. For data to transmit and receive from one Xbee module to another, both devices should be on same network. The data between two devices is transmitted wirelessly. By serial communication (UART), the Xbee modules can communicate with microcontrollers and processors.

A microcontroller, processor or PC can send data through the serial interface to the Xbee module (transmitter) and the Xbee module wirelessly transmits the data to other Xbee module (Receiver). The receiver Xbee module transmits the data through the serial interface to controller, processor or PC to which it is interfaced. The controller interfaced to the Xbee module processes the information received by the Xbee devices. This way, controllers can monitor and control remote devices by sending messages through the local Xbee modules.

The Xbee modules communicate with each other in two modes – Transparent mode  and API (Application Peripheral Interface) mode. This project is based on Transparent mode. In transparent mode, Xbee modules act as serial line replacement. All data received through serial input is immediately transmitted over the air. When other Xbee module receives data wirelessly, it sends that exactly as it receives through the serial interface and vice versa. Contrary to this, in the API mode, the data is transmitted with some additional information.

In this project, two Xbee modules will be interfaced with two PCs and they will be configured to communicate data with each other in transparent mode. The XCTU software can be used on the PCs to send and receive data between the PCs and the Xbee modules.