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How does a PLC programmer work?
How can a PLC move an entire plant?
A PLC is a vital part in an industrial automation plant. Such devices are, indeed, the brain of industrial machineries.
As we told in a previous article, a PLC detects input signals, process them and activates the digital (or analogic) outputs to run the whole line. But how is all of this possible? Well, you will first need a PLC programmer that knows his trade.
How does a PLC programmer work?
CEI EN 61131-3 regulation standardised 5 programming languages that PLC operators can rely on, languages supported by the different softwares available on the market. Thanks to these specific softwares, it’s possible to write coding lines that can be later uploaded in the PLC memory. The newly created software, however, is not immediately connected to the programmer’s PC for any editing: it must first be tested and then it will be possible to edit it, if needed.
PLC programming begins with a functional analysis of what is the problem to be solved in an industrial automation plant, i.e.: what the software has to make the machines and the plant do. After collecting this information, it’s necessary to understand which and how many signals are introduced, how long do they last and their characteristics. Later, the programmer needs to have an exact and detailed definition and description of the plant functioning, in order to better and more accurately code the PLC application software.
From programming to start-up
Earlier we talked about an analysis of the input signals, we now need to understand when and how long the output signals need to last. Immediately after, the programmer makes an “I/O occupation list”, a list that allows the programmer to know in which entry a specific sensor is connected and in which exit the relative actuator is connected. This passage is fundamental to allow the signals to reach the correct machineries in the automation plant.
Once the creation of the software is done, it’s time to work on the details and get the specifications right. During this last phase, the software is run on an emulator platform, normally called “test bank”. Using this “bank” it’s possible to analyse the PLC behaviour, simulating different situations that might arise on the plant, making sure the software reacts the right way.
What can a PLC do?
Long story short: A PLC programmer is something between a technician and the director of an orchestra that, starting from basic information, can create an application software capable to coordinate an entire industrial system.
Since every PLC software is specifically programmed for the production plant it’s going to be installed on, the possibilities for programmable controllers are virtually infinite. If the programmer knows what an industrial plant has to do, along with the specific characteristics of the signals to exchange, the application software can be programmed in any imaginable way. We are talking about features that range from moving an conveyor belt to coordinate a robot for quality control.