X10 protocol in a “smart” house: should we live on with a veteran?

The article discusses the devices of the "smart" home, working using the X10 protocol.

Communication Protocol History X10 for controlling household electrical appliances from a central console has nearly four decades. It was developed back in 1975 by Pico Electronics and quickly acquired the status of the de facto standard. This happened thanks to the ingenious engineering solution: use the electrical wiring of the house to transmit control signals.

The idea was developed in industrial PLC modemsused today to transfer data from electric meters to power wiring. An example is the Mercury counters of the Incotex Moscow company. But, unlike its progenitor, this data transfer protocol is closed because it uses a proprietary data encoding algorithm to achieve high noise immunity.

Today, only firms manufacturing products compatible with the X10 protocol have dozens, if not hundreds. Chinese manufacturers added to them home automation products with the S10 protocol, which is, if not a clone, then certainly the X10 sibling. But the abundance of products on the market and the huge former popularity does not mean that this standard has no problems.

To get started, briefly get acquainted with features of data transmission through the power network of the X10 protocol. All products that meet the protocol can be divided into transmitters (sources of control signals) and receivers, or executive schemes. Control signals are transmitted when the voltage crosses the zero value.

The transmitter, having determined the moment of zero transition, with a delay of no more than 200 microseconds, gives a control signal of 1 ms duration in the form of a packet (train) of oscillations with a frequency of 120 kHz and an amplitude of up to 5V. The signal receivers at this time “open” a time window and “listen” to the network. When a signal appears in the allowed time, it is processed. In the original version, 256 receivers could be controlled. A more detailed description of the protocol can be found in numerous sources. We will not need more detailed information for discussion.

A feature of the X10 protocol is the serial transmission of binary instruction codes. For one transition through a zero value, only one bit of information is transmitted. Therefore, this is a very slow protocol: transferring a standard command to turn a device on or off takes about a second. You can still put up with such inconvenience.

But the following drawback can seriously limit the lifetime of a long-lived standard. It's about extremely low noise immunity of devices working with the X10 protocol. Since the invention of the protocol, the world has changed dramatically. If in the seventies the main household source of interference was discharge lamps and hair dryers with a collector engine, today this list has expanded significantly.

Almost every house or apartment has TVs and computers with a switching power supply. Pulse power use modern economical lamps. Even ordinary Charger contains a nonlinear current limiter - a capacitor. Such an abundance of non-linear loads “pollutes” electrical networks.

The degree of “pollution” of electric networks is so high that it is difficult to compare even with noise in the radio bands. There have long been strict rules governing the operation of radio equipment. The requirements for the quality of electric networks are accepted in the USA and European countries (Euro norms), but they cannot guarantee the operation of X10 standard equipment without failures.It is better not to talk about the quality of energy in the networks of the CIS countries at all - it is depressing.

Under these conditions, information transmission over electric networks is possible only with a sophisticated coding system by noise-tolerant algorithms. And in the X10 protocol, only one control bit and amplitude modulation are used in commands. Therefore, most users of devices operating in the X10 standard complain of malfunctioning commands.

To combat external interference and unauthorized access to the system, filters are installed, for example, the FM10 module, which is part of the X10 line of units. But with the increasing number of sources of interference inside the house, several such modules may be required. All this complicates and overloads the system with auxiliary units.

In general, analyzing the abundance of devices compatible with X10, the seditious question arises: "Isn’t it easier to abandon the standard, which has so many shortcomings, and move on to building a system based on a modern protocol?"

Modern set of remotes operating using radio channelsquite copes with the tasks of home automation autonomously. Therefore, embedding an additional X10 support function in them is more a tribute to tradition than a necessity.

Indeed, to enter a control signal into the power network transceivers are required, which complicates both the control panels themselves and the system as a whole. You also need to add information signal repeaters, voltage drop filters, signal blockers, bridges for communication with different phases, etc. The list of auxiliary equipment that increases the reliability of the system has long exceeded the complexity of the basic devices of the system itself.

For whom then is all this released? The fact is that in the United States alone, about 5 million homes are equipped with X10 protocol automation systems. No fewer systems operate in Europe. Since the advent of the standard, more than 100 million products have been sold. Manufacturers are guided by these consumers, continuously expanding the list.

But for those who are just thinking to tackle a fascinating problem creating a "smart home", focus on the X10 standard and equipment supporting it is not worth it. Today, the market offers modern products for home automation, performing an extensive range of tasks: measuring temperature and humidity, managing loads directly and the timer, and much more. Moreover, they are much more reliable, and often cheaper.

It is important to consider one more feature - products from different manufacturers may not be compatible with each other. Against the background of all these problems, such shortcomings as the lack of acknowledgment (feedback from receivers) and insecurity from unauthorized access look like just small roughnesses of the standard.

And one more thing: for all its flaws and respectable age, X10 standard products are far from cheap today. The simplest basic set, consisting of a remote control and a receiver, costs from $ 200, and each additional unit is still an average of $ 30. And the products of "reputable" manufacturers, for example, the Belgian company Xanura, will cost $ 2,300 for a multifunction controller and 300 for an IR transceiver.

Therefore, those who prefer this standard should be very careful both in determining the tasks that your smart home system will solve and in choosing device suppliers. The best option is to buy X10 Inc products, which are widely represented in the CIS markets, but other options are possible depending on your financial capabilities.