The process of writing the instructions, sequence, and calculations that the PLC will utilise to automate a machine or process is known as PLC programming. The programme is the intelligence, while the PLC is the hardware.
The PLC’s programming essentially gives a machine a “brain.” Programmable logic controller is known as PLC.
A corporation by the name of Modicon invented the PLC in the 1960s. It was initially used in automotive manufacturing facilities to replace outdated relays that were set up to generate relay logic. It was a straightforward decision-making and management system that worked well for the time, but as usual, there’s always room for improvement.
In a nutshell, a relay is a mechanical switch that is turned on and off by an electrical source.
It is bigger than an electrical device since it is mechanical in nature, and moving parts wear out, deteriorate, and eventually stop working. There are numerous relays needed to build the appropriate relay logic, as well as many more wires to connect them. Rewiring is required if the reasoning is flawed or has to be updated. In order to generate logic circuits and bring them virtually into the programme, the PLC eliminates all of these physical relays.
Ladder Diagram or Ladder Logic has predominated in PLC programming and continues to do so. Despite there being other languages, it is still the most often used language for programming a PLC. The simple explanation is that it closely resembles the electrical schematics used for relay logic. Common electrical symbols, such as those used for contacts and coils, are utilised to programme ladder logic. Since a ladder diagram programme resembles an electrical drawing that electricians are accustomed to and conversant with, switching from hard-wired relays to a PLC was made simple.
Certain abilities and expertise are needed to programme a PLC. It is crucial to comprehend the process that will be automated or regulated. When the primary operations of the machine or process are the emphasis at first, the start-up and shutdown processes are frequently overlooked or given little consideration.
The PLC must be chosen to suit the application, with all inputs and outputs taken into account, replacement parts supplied in case the project expands or to cover components that were merely overlooked.
As with any endeavour, planning beforehand will help you avoid delays and difficulties. Meeting with all the participants or stakeholders would be an excellent starting point. Discuss the details, create a timeline, and get everyone’s approval before moving further. If additional features or functions are later desired, you can provide evidence for why the programming project took longer than anticipated.
The process of automating a machine involves many steps, including PLC programming. The components that supply the PLC with its inputs and the outputs it will control must be designed and specified by an engineer.
If you are just in charge of programming, the engineer must provide you with a list of all the inputs, outputs, and their specifications. He or she might also be the one to provide a control narrative or project description. In a later stage of development, Boolean Logic diagrams may be provided to you, the programmer, from which you can build the programme if they are sufficiently comprehensive. The programming and perhaps the HMI programming are frequently done by the controls/electrical engineer, but that is a different discussion.
In conclusion, PLC programming involves using a specialised computer to give machines and processes a brain and calls for a high level of expertise. In terms of difficulty, ongoing learning, teamwork, and last but not least, financial gain, I can attest that it can be a highly satisfying profession. Read More about HMI programming