The simplest device for transmitting data over a power network?

Question

Do it yourself

Greetings dear ones.
I'm thinking about one idea, but I'm not familiar with the subject area.
I know there are protocols for data transmission over power networks. X10 for example. It is necessary to find or develop a device that, when connected to the network, simply transmits its serial number to the line. Transmits regularly at some fixed interval. Like "I'm online".
The device should be as cheap as possible, with the ability to set a unique serial number (better - hardwired at the production stage). Of course, the device must be able to be powered by 220V and at the same time remain cheap and compact.
The protocol does not really matter yet, but I heard that X10 does not work well if there are a lot of devices on the network. There will be many devices.
In addition, you need a central device (not necessarily cheap anymore), which will collect information from peripheral devices and transfer it to some server.
Tell me, maybe there are ready-made solutions, or components and technologies that are worth studying.

Answer 1

Maybe this will suit you? en.wikipedia.org/wiki/Communication_by_power line

Answer 2

X10 is designed for “one transmitter - many receivers”, and your situation is the opposite: “many transmitters - one receiver”.
If you do not use two-way communication, it will be quite difficult to avoid collisions. You can use pseudo-random time intervals between bursts.
As a physical layer, you can look at the m / s KR1446XK1, LM567, TDA5051, ST7538 / ST7540. Ready-made PLC-modems are unlikely to meet the "as cheap as possible" condition.
www.soel.ru/cms/f/?/376853.pdf
kazus.ru/forums/showthread.php?s=e39bbb45ec79fe3141debff570162db2&t=17551

Answer 3

If you are going to make your device from scratch, do not count on any transmission reliability. The protocol should be as concise and obtuse as possible. Also, it must be understood that the RF signal, and this is how data is transmitted over network 220, is strongly attenuated in this network. Say, more than 50 meters is already a problem. Retransmission solves this problem, but then the modem is quite expensive. By the way, if all devices work as repeaters - I watched such a thing - the network simply chokes.
Further. Frequencies. Carrier frequencies in industrial modems are about 20 kHz (PLC 1) and 78-90 kHz (PLC II). The second range is not so clogged with interference, however, as practice shows, interference in the network is simply OMG. For example, a switched on energy-saving Chinese light bulb can clog a network segment with a radius of 15-20 meters (a couple of floors in the entrance).
The transfer rate for the PLC, by the way, is 300 baud.

Answer 4

Dofiga and a bunch. In the case of using wireless devices, the problem of registration immediately arises when a certain threshold is exceeded. I don’t remember exactly, but in my opinion, up to 10 mW - you can use it safely. 10mW will not break through 50 meters indoors (a vivid example is Wi-Fi. You can’t catch a signal from a point on the first floor on the 9th floor?). On the street - easily. We can use modules at 433 and 2400 MHz. 433 has a much higher "penetrating ability". Modern wireless systems for collecting data from meters are based on 433 MHz modules. At the same time, in the case of creating a network, a lot of power is not needed. For example, ISTA radio modules use transceivers with a power of only 1 mW. But they all work as repeaters, and it takes a week or more to create a network of sensors.
You can see these modules:
HopeRF RFM22B / RFM23 (200/10 mW)
3DR radio - ready-made radio modems also on Hoper's NRF24L01 modules
- cost a penny, no power, there are ready-made libraries for working with them (however, as for those mentioned above)