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Application of PLCs in Smart Homes – Insights from an Experienced Electrician

Two days ago, Engineer Zhang from my community approached me, saying that his “smart home” system was constantly malfunctioning, and the system he spent a lot of money on was less stable than a regular switch. Upon inspection, I found that he had hired someone to install it haphazardly, with various brands being incompatible and the automation logic not properly configured. What a waste of money! I immediately re-planned a home system based on PLCs for him, and the results were excellent!

PLC stands for Programmable Logic Controller, and don’t be intimidated by the name; it’s essentially a “super switch” used in industry, far superior to those incompatible smart home systems. I have used them in factories for over a decade without major issues.

Young Wang, don’t let my age fool you; using PLCs at home is much more stable than those so-called smart speakers or mobile controls. Why? Because PLCs are designed to operate continuously in harsh environments, and the load at home is a piece of cake!

Let’s talk about how to use PLCs for home lighting control. The simplest way is to program your living room light like this:

LD X0    // Entrance button input

OUT Y0   // Living room light output

LD X1    // Sound sensor input

OR Y0    // Maintain current state

OUT Y0   // Final output to the light

With just these few lines, we have implemented button control along with sound control. Traditional smart home systems would require hundreds for dedicated modules, but I achieved it with PLCs for just a few dozen.

Some may ask, can PLCs control temperature? Of course! The temperature control system I installed for Engineer Zhang’s home is quite simple:

PLCs have far superior analog processing capabilities compared to typical home temperature controllers. A regular temperature controller simply switches on or off at a set temperature, while PLCs can achieve smooth control, making it more comfortable and energy-efficient.

LD AI0    // Read temperature sensor value

SUB K250  // Subtract set temperature of 25.0 degrees

BLT CLOSE // If below set value, turn off cooling

SET Y1    // If above set value, turn on cooling

As you can see, this is where PLCs excel compared to traditional temperature controllers; the temperature fluctuations are minimal, avoiding sudden hot and cold, and saving on electricity bills.

The most impressive feature of PLCs is their interconnectivity. I remember last week, Engineer Zhang asked for my help because various brand smart devices in his home could not work together. I laughed when I heard this; it’s a strong suit of PLCs!

PLCs can serve as a central controller to connect various brand devices. For instance, his original smart curtains could not interact with the temperature control system, so I used a PLC to act as a “translator”:

MOVW D0 D100   // Read curtain status to data area

LD X7          // Check if it is a direct sunlight period

AND D100.1     // Curtain open status

OUT Y5         // Control air conditioning to enhance cooling

Young folks, remember, when doing smart homes, the biggest fear is having one brand with a separate system, each acting independently. The greatest advantage of PLCs is their “compatibility and inclusiveness”; almost all devices can be integrated for unified management.

Speaking of convenience, PLCs also excel in remote monitoring. I added a communication module to Engineer Zhang’s home for less than 300 yuan, allowing him to see the situation at home while on business trips and even control it remotely. Just think about how much those professional smart home systems would charge for this feature!

PLC ladder diagram programming is simpler and more intuitive than smart home platforms. I trained a few young people, and they could grasp basic programming in just two days. Look at those smart home platforms; just registering an account and connecting devices can take half a day, and you have to worry about the manufacturer going out of business and shutting down servers. With PLCs, the program is stored in the controller, so there’s no need to worry even if the sky falls!

In fact, the most important aspect of smart homes is practicality, not flashiness. Many people buy smart speakers, but once the novelty wears off, they gather dust. PLCs, on the other hand, are customized based on your actual needs. For example, creating a wake-up mode: at 6 AM, the curtains automatically open, the coffee machine starts working, and the bathroom water heater preheats. All of this can be achieved with just a few timers in a PLC.

Remember, when selecting devices, don’t be swayed by brands; focus on practicality and stability. PLCs have been used in factories for decades, and their reliability has long been proven. Using them at home may seem like overkill, but they will definitely not cause any issues.

Young Wang, don’t underestimate this old man; I may not keep up with the times, but when it comes to control systems, I still have my skills. If you’re interested in PLCs, feel free to come to me. No matter how smart the work gets, it still relies on solid industrial technology as a foundation!