One of the most valuable characteristics of building your own home automation system is the ability to personalize it by picking and choosing the devices that meet your needs. However, there are times when you require a product to perform a certain function and that product may not exist for the protocol of your choice.
The history of the X10 protocol dates back to the mid 1970s and X10 devices are still in production today. Throughout the lifetime of X10, engineers and hobbyists have created a large variety of device types from wall modules to light switches, motion sensors, water leak detectors, drive way sensors, and much more.
Eventually, we will probably see similar devices available that utilize the Z-Wave protocol. But until then, we can use existing X10 devices to meet our needs. How can we allow the different protocols to interact with each other? We do this by bridging the communication gap between the two protocols using a home automation controller.
The X10 protocol is known as a power line carrier (PLC) protocol and how it works is straightforward. In the United States, home-based power alternates current direction 60 times a second. Each time it changes direction the voltage at the point of change is zero. X10 sends data over the home's power lines as close to this point as possible.
By contrast, the Z-Wave protocol is known as a wireless mesh network protocol and it does not rely on the home's power lines to transmit data. Everything is transmitted using a radio frequency (RF) signal in the 908 MHz signal band.
So there is an obvious communications barrier between Z-Wave and X10! They not only speak different languages but they also use two very different methods of transportation. So how do we cross this barrier? By building a bridge using software or hardware. Basically we need something that speaks both protocol languages and provides a logic engine.
The inexpensive solution to this problem is to use a software product such as HomeZix or HomeSeer. You would then use a X10 PC controller such as the W800RF wireless X10 receiver or SmartHome PowerLinc PLC. Both of these X10 controllers communicate with the software using the computer's serial port.
You would also need a Z-Wave PC controller, which comes in many varieties including USB, serial, and Ethernet. HomeZix and HomeSeer both support speaking the X10 and Z-Wave language and they both have built-in logic engines.