What Is a PLC and How Does It Work?
What is a PLC?
A small computer that has been designed to perform particular actions or outputs in response to inputs and a set of rules is known as a programmable logic controller.
Airports, office buildings, railroads, and manufacturing facilities are just a few of the commercial and industrial contexts where PLCs are utilized. We’ll go over the consequences of PLCs in the manufacturing industry explicitly in this post.
Using a PLC to connect your systems and equipment is different from the more conventional method that uses relay logic devices. Although electrical relays function similarly to a PLC in controlling industrial processes, they have serious limitations in terms of maintenance and configuration.
Because electrical banks are composed of a system of physical wiring, the physical connections would have to be entirely rewired if the system’s operation ever needed to be altered.
How does a PLC work?
The steps involved in basic PLC functioning are as follows:
- Determine the condition of the PLC’s input devices.
Data inputs come in two varieties: discrete and analogue.
Discrete
- Data that is in one of two states, such as on or off, 1 or 0, open or closed, is referred to as discrete input.
- A valve state (open/closed) or a push button switch (on/off) are two examples.
Analogue
- Signals with a range of values, as opposed to just on/off or open/closed, are referred to as analogue input.
- Weight scales, temperature, pressure, and CO2 sensors are a few examples.
2.Based on input, carry out program instructions.
3. Run every output device that is linked to the PLC.
- Alarms, indicator lights, valves, and/or visual display outputs are a few examples.
Benefits and Limitations of using a PLC
Benefits
Businesses have turned to innovative methods of automating procedures and streamlining production as a result of the expansion of machinery throughout a manufacturing facility. The use of programmable language controllers to connect and manage the different machines, devices, sensors, etc. resulted from the rising automation. PLCs offer producers a number of advantages, such as:
Relay systems make the entire process more difficult by requiring manufacturers to handle complex logic sequences. Conversely, PLCs can be used to operate a variety of industrial applications using simple programming languages.
More flexibility: A PLC makes it simple for enterprises to modify their production procedures if necessary. This is because, in contrast to having to disconnect and reconnect a complete relay circuit, the logic program may be readily modified via the linked computer. Over time, this makes maintenance and troubleshooting simpler.
Increased dependability: PLC-centric automation requires less wiring, which reduces the possibility of faulty physical connections. Manufacturing processes can therefore proceed more dependably.
Quick reaction time: Modern producers must react to in-factory incidents right away. PLCs allow machinery to react instantly to inputs by controlling it in real-time.
Physically sturdy: PLCs are made to withstand potentially harsh industrial environments including heat, dust, and debris.
Limitations
For many years, PLCs have performed their duties effectively. That is not questioned. They do, however, get headaches. The flaws in conventional PLC installations become apparent as facilities become more interconnected and production shifts more quickly.
It’s not easy to scale up. More hardware, more wiring, more cost.
It can be difficult to send data to contemporary systems.
Not every site has the skilled individuals needed for programming.
Even minor adjustments may require re-validation and downtime.
You are typically stuck with a vendor once you choose one.
Thus, they still make sense in many contexts. However, PLCs can be holding you back if you require speed, flexibility, and more seamless connections to contemporary applications.
PLC vs. Industrial computer
While industrial PCs (IPCs) are strong, adaptable computers that excel at handling complicated data, advanced analytics, and multitasking like running HMIs or AI applications, PLCs are specialised for high-reliability, deterministic industrial control operations. While IPCs offer more flexibility, expandability, and processing capacity for complicated applications but necessitate additional security measures, PLCs are more robust, affordable for basic tasks, and have a more constrained, secure operating system.
Factors to consider when selecting a PLC
Before purchasing a PLC, producers must take into account a few important criteria when using programmable logic controllers for factory automation.
System compatibility: Manufacturers should be aware of whether their preferred PLC is compatible with the production systems they currently use. Furthermore, the PLC must be compatible with the voltage of the factory’s power outlets.
Processing speed: To manage the different operations and activities at a particular facility, the PLC’s CPU should have sufficient processing speed.
The quantity of ports: Making sure the PLC has enough input and output ports to meet production needs is a sensible move.
Analogue I/O capability: Some PLCs are limited to discrete, basic on/off operations. Nevertheless, some production processes are analogue, necessitating the use of a programmable logic controller capable of managing continuous variables.
Durability: A lot of manufacturers place PLCs close to the relevant equipment. As a result, it’s critical to make sure it can withstand industrial ambient elements like high temperatures.
FAQ
What is a PLC and how does it work?
Programmable Logic Controllers (PLCs) are industrial computers, with various inputs and outputs, used to control and monitor industrial equipment based on custom programming. PLCs come in many different sizes and form factors.
What is the difference between PLC and industrial computer?
However, industrial computers are typically equipped with more advanced processors, which allow for superior performance in handling complex control and monitoring tasks. PLCs are associated with ladder logic programming, which is tailored to the needs of industrial control.
What is the main purpose of using a PLC?
Automating and controlling particular machines, systems, or processes is the main function of PLCs. PLC systems, for instance, accurately control tasks like operating conveyor belts, scheduling the activation of motors, and regulating heaters to a predetermined temperature on a production line.