XBee Wireless Serial Module
The XBee wireless serial module is developed by Digi International. It's a radio that provides a simple and reliable way to add wireless communication to any project. An XBee module requires just four connections: 3.3V supply, power ground, receive, and transmit. You are also able to control various settings of the XBee through a program called X-CTU. Settings like: the channel that they transmit over, baud rate, flow control, the works!
The three main practical advantages of using an XBee system over a WiFi or similar setup are: range, flexibility, and simplicity. With an XBee system you can achieve considerable more range than a standard wireless router. Especially when you move to a lower frequency like 868 MHz. Digi boasts up to 80km (!!!) with some of their modules. Thanks to the incredible ease in configuring the basic settings of the module you can configure multiple networks to work in the same area, or you can even set the modules to work as a mesh network in more complicated and expansive use-cases. The prime feature of an XBee is its ease of use. You are relieved of managing a more complicated Ethernet or WiFi protocol and just have to manage a single Rx and Tx serial connection. What you send into one of your XBee modules appears out of the other. Out of the box, you can connect the modules to the Rx and Tx of your system and you're off. In a basic setup, no configuration is required. It couldn't be easier.
A common term that you may hear when discussing or researching XBees yourself is Zigbee. Zigbee is an alliance and standard of cost and energy efficient mesh networks. XBee employs the Zigbee standard and adds to it and wraps it up in their own neat little package. This is one of the main contributors to the enhanced range of the modules over a standard WiFi radio.
Related Link: Zigbee Alliance
Series Descriptions
XBee modules come in a wide variety of shapes and sizes. For example, we carry the XBee 3. These are 2.4 GHz radios that boast 300' (100m) indoor/urban range and 2 mile (3200m) line of sight range. They transmit using a 79mW radio. These radios are also available with a variety of antenna options, such as a PCB trace antenna, wired antenna, and a U.FL connector to attach an external antenna. There are non-Pro versions of the Series 1 available, but the trade-off is range and in most wireless applications it would be a severe limiting factor.
You also have the option of frequencies. You have the standard 2.4GHz that share the same frequency bands as WiFi but you also have lower frequency modules like 868 MHz and 900 MHz. These lower frequency modules limit you in how much data you can push through the network at a given amount of time, but you receive a significant boost in range. I should note that you can NOT mix and match different frequencies on the same network. You have to be either all 2.4 GHz or all 900 MHz for your system to work.
XBees can come with a variety of antenna options. Some have a chip, or trace antenna that lives on the circuit board itself. These are simpler in that you have no external antenna to knock off. They are also safer by preventing you from accidentally powering the radio without an antenna attached. But you do sacrifice range for this simplicity. As an alternative, they can come with a wire antenna that comes soldered to the module itself. This will give you more range than a chip or trace antenna. Finally, they also come with a variety of RF connectors like U.FL and RPSMA. These allow you to attach a much larger and higher gain antennas to provide even more range for your solution.
Bridging the Gap to the Internet of Things (IoT)
Although the XBee modules themselves operate on a different protocol than WiFi, they can be bridged to the Internet of Things using a USB Adapter Board. This adapter board allows your XBee network appear as a COM port on your computer. Once you have this link, you can write your own software to access your XBee network from your local home network, or the internet at large. For more information on connecting your device to the IoT, please follow this link to Digi's website.