What are the benefits and challenges of using PLCs for sensor and actuator control in smart factories?

PLC's are an effective control and information consolidation point where they are not often tasked with enterprise level communications and can be physically setup to be isolated from the enterprise network to prevent any compromise of safety, Process security and real time operations not allowing enterprise interrupts from needed immediate control. Recipes and variables can be exchanged without compromising the core programming and limitations of the system. So long as a electronic and Physical programming isolation is maintained from the enterprise network. The difference of Programmable logic control and real time Kernal operations on a server or PC system are getting more blurred, but PLC's are still reliable over a long term.

A quick look and comparison of a controls cabinet controlled with relays and a PLC controlled cabinet with an HMI will quickly show the benefits a PLC has. Cabinets using relays and indicator lights can be overwhelming to look at and troubleshoot if not well documented or if there are any abnormal failures. PLC controlled controls cabinets tend to be much simpler and easy to trace the wiring. There is also the huge benefit of being able to easily display the conditions of the sensors and process on an HMI if necessary. While odd failures can also occur in a PLC, they are much less common and most issues can be diagnosed in a graphical user interface. Some PLCs also allow online changes to the control programs without any process stoppage.

PLCs can be layered in a way that other systems simply cannot support. A sensor array PLC can have all of your inputs. A safety PLC can be laid on top of that for all of your safety chain functions. Your control PLC can take information from the safety PLC and the sensor array PLC to make informed decisions and all of those can be separated by various firewalls, password protection and other things. Like everything else in the electronic world. However, garbage in equals garbage out so every layer needs to be tested within an inch of its life. But once it's set up and working reliably, it can stay that way until something fails. Depending on the end process or the end product, you will write your code in the safety PLC to fail safe.

Once our code was embedded into the system we are identified with some alarms written on the code because the system is not matched with requirements in the initial stage. So we need to eliminate all these alarms by rectifying the errors one by one. There may be a problem with the controllers, sensors, actuators, device connections, safety equipment etc. So in my opinion a PLC programmer should have knowledge in many sectors like Electrical, Mechanical and Electronics. We need to take care of the software part, and if an error or problem occurs to be identified and resolved for example if there is a problem with the power supply of a component we need to study the electrical schematic diagram etc.

You need to first learn the basics of PLC programming (such as data types, declaration of variables and tags, and the standard PLC programming languages), and then keep practicing using the freely available software platforms for PLC programming such as CODESYS. There are plenty of tutorials for most of the platforms that makes learning easy and fast. After learning the basics, it would be great to pick up a scenario and develop a program to control the system. It is recommended to start with the general case and then add the details (like the top-down design).

If you're new to coding, you may want to look into using other people's codes, there are no end to the resources available to people working with almost every PLC on the market. Or even better if you're really brand new start building your own code, test it. Make sure you do it in a safe environment where you're not actually controlling the end process and you'll be fine. Plus the education you will develop will be unparalleled.