XBees - Arduino - page 91

other hand, may need to use a mesh protocol to be more robust in getting the data to the endpoint, with the range
not being as important. To avoid issues in debugging, and for best results when purchasing a first set of XBees, match
modules according to the series number, transmission power, and antenna type.
There may be a need in some projects to mismatch the modules, such as when using two modules with greater
range and having others in the network with lower transmitting power to more effectively cover an area. Keep in mind
when mixing the ranges of the modules that they can usually receive data at a faster rate than they can transmit data.
Another possible mismatch comes with pro versions of XBee modules. Pro modules are clearly labeled with the word
Pro on the module itself; these modules provide an integrated programmable microcontroller that acts in the same
way as attaching an Arduino to a standard XBee module. The pro modules are useful for stand-alone operations
or removing overhead from the Arduino itself. The move to the pro module is not necessary, and can add more
complexity because the microcontroller used is made by Freescale and has a programming methodology different
from the Arduino.
Here are the different series (series 1 and 2 are the most commonly used in Arduino development):

• Series 1 : This series has a network topology of spoke-and-hub or point-to-multipoint and
uses the 2.4 GHz frequency band. Series 1 modules can be configured and used out of
the box without extra software. This series works well for remote control applications and
simple sensor networks. All communications go through a central node; outer nodes cannot
communicate with one another. This series has a rage of 300 feet to 1 mile.

• Series 2 : This series is a bit more complicated than series 1, but provides more functionality
and flexibility. It's capable of mesh networking , which closely resembles the common wired
networking topology of an ISP, router, and computer. There are three different internal
firmware options that can be used for a mesh network.

• There must be one controller in the network, which functions like a DHCP server or ISP.

The controller assigns the address and determines if a new node can join the network.

• Mesh networks also include router firmware and allow for multiple routers in the

network.

• Routers connect to the controller and to endpoints, which are the third firmware option.

Both the controller and router have to be powered all the time and cannot take advantage
of the power-saving feature of sleeping; this is due to the modules keeping track of routing
information. The endpoint can be put into a sleep state. This series is usually marked on the
board by an S2 below the XBee markings. There are two other variants in this series: S2B
and S2C. S2B is the pro package and S2C is a surface-mount package. The regular S2 has
the standard XBee through-hole configuration. This series has a range of 400 feet to 2 miles.

• Series 3 : This series offers a 900 MHz point-to-multipoint module with about 6 miles of range.

• Series 4 : Modules of this series can be used for proprietary Digi mesh and point-to-multipoint;
they have an approximate range of 1.8 miles using 900 MHz.

• Series 5 : This series is licensed for European point-to-multipoint in the 868 MHz band; it has
about 25 miles of range.

• Series 6 : This series offers a WiFi module packaged in the XBee format. It uses SPI or UART for
connections and can work on B, G, and N networks.

• Xtend : Modules of this series have a range of 15 miles, the longest available for use in the
United States. They communicate at 900MHz. The network topology is proprietary multipoint
or proprietary mesh.