PLC Programming Overview

PLCs take the operators commands from the SCADA system and turn them into reality. They provide the signals to control equipment, logic to ensure things happen safely and in the correct order, and make your process as repeatable as possible.

PLCs, robotics and other automation tools take away the monotonous, strenuous, and dangerous work away from your operators freeing them up to do things best accomplished by humans. Automation increases productivity of your process, improves quality, and helps your people get more done in the same period of time.

When designed properly PLC logic is easy for your maintenance staff to use as a troubleshooting tool. Like any programming language, it requires skill and experience to write efficient and error free code, however it only needs to be as complex as necessary. When something goes wrong with equipment, a PLC can be your most valuable tool to the process up and running quickly, reducing downtime.

Automation saves you money, operates your equipment more safely, and increases your facility’s throughput. 

Already have a PLC?

Which PLC is best for my system?

Choosing “the best” PLC for your system depends on a number of factors including, but not limited to:

  • What do you have currently or what are you used to using?
  • Do you need redundant PLCs?
  • What type of I/O does your process require in your PLC?
  • Does your architecture use modern protocols like MQTT?
  • What SCADA or MES System are you using?
  • Do your PLCs need to communicate with one another?

We have helped many companies determine the right PLC for their needs, and can help you as well if you would like.

Some facilities might be able to use a small PLC with built-in I/O and not a lot of expansion possibility, while others may want a fully distributed architecture capable of hundreds of thousands of I/O points.

You might want to use different programming languages to build the PLC logic. Most PLCs support ladder logic out of the box, and may also include the other IEC 61131-3 languages, or may require additional software to support those.

In the end it comes down to who will be doing the programming, what you need the PLC to do, and what systems will be pulling data from the PLC. Once you filter the list through those items you will have a better idea of what is available and can start to look at things like price, security, and what looks the coolest.

PLC Software and Languages

In order to actually program the PLC, you need software to communicate between your computer and the PLC. This software lets you build the control logic, then turns it into instruction the PLC can understand, and loads the code into the processor. Each brand of PLC has its own software package, and some use third party packages like Codesys.

Sometimes you have to buy this software (Rockwell, Siemens, GE) and sometimes it is free (Bedrock, Codesys, EZAutomation). Paid vs. free is more a function of the manufacturer’s business models than quality of the software, so don’t be scared off by “you get what you pay for”.

In order to program a PLC, you can choose from various “languages.” These languages are spelled out in IEC 61131-3 and consist of Ladder Logic (Ladder Diagram), Function Block, Structured Text, Sequential Function Chart, and Instruction List. Of this, Ladder Logic (LL) is the original and most prominent in the field. Much has been said and debated over which of these languages is best at the end of the day, and if you have questions we can help you decide which language would work best for you.

No PLC (yet)?

Why might I want a PLC?

PLCs can take the place of pushbutton controls on your machines, allowing you to integrate with an HMI or SCADA system to control your equipment. A single PLC can be used to control multiple pieces of equipment, or even an entire facility.

If you are looking for automated machine control, be it robotic, furnace, brewing, or anything else in-between, a PLC is what you want. PLCs are used in critical applications in all industries, and give you repeatable results.

If you work at a facility and are not using PLC’s, please drop us a line. We can walk through your process and see if a PLC would help you, give you an idea of what it can do, what it would cost, and get you into the wonderful world of automation.

Are there other options for my system?

Despite all the wonderful functionality PLC’s can offer automated processes, they’re not for everyone (here’s looking at you, non-automated, software-using breweries!).

If you belong in this category, Corso Systems can provide many non-PLC solutions that can benefit the performance, output, and functionality of your system.  Check out Brewtel by Corso Systems if you have a brewery, and or more into what MES might be able to offer you in terms of monitoring, scheduling, and management.

As always, feel free to reach out any time if you have questions about anything or want to know more about what Corso Systems can do for your company.

How do I get started?

Getting started takes a couple paths depending on your project. If you are looking to upgrade your current PLC’s, we can run through what it takes to convert PLC from one model or brand to another. If you are looking for new PLCs or your first PLC, we can run through all of your options and help you make the best decision for your business.. It is an extreme rarity for one of our project to not have PLC programming included and we can talk you through any scenario you might be able to dream up.

Want to get the most out of your PLC? Learn about visualizing and controlling your PLC’s in our SCADA and HMI sections.