Which PLC Hardware to Buy, When to Invest & What You Should Know before Purchasing PLCs
Introduction
Learning different platforms can be very exciting. However, as the excitement diminishes and we get to some of the most difficult concepts, it could be tempting to switch platforms, purchase new hardware or to spend time elsewhere. This is the reality a lot of us have faced or will face at one point or another.
I receive this question quite frequently, but this one was much more thorough than some of the ones before. I believe it’s time for me to write a dedicated post about this topic and give you my perspective on when, why and which PLCs / HMIs systems you should invest in.
Learning PLC Programming Takes a Long Time
It takes a long time to become a good PLC Programmer. You can grasp the basics of it within a few weeks, but it can take a lifetime to master. Although I wouldn’t recommend it, I personally know engineers who’ve focused on a very narrow branch of PLC programming for their entire career. In fact, Rockwell Automation has engineers who’ve done nothing but Servo Motion.
The point I’m trying to make is that it may be tempting to switch gears and experience the rush of learning something new on a regular basis. However, this isn’t the right approach if you want to become an expert in the field. You need to make sure that you stick to the craft and explore the different features within the same platform.
If you believe that you’ve had enough exposure to ladder logic programming, see if you can write a few programs in function blocks, master a PID loop or build a sequence which rejects a product. Look beyond what you’re currently working with and see what else can be implemented.
Keep learning & mastering the craft.
Practicing on a Standalone PLC is Challenging
There are several learning stages through which every programmer, PLC or otherwise, goes through. First, you start watching videos of someone programming. You then download a simulator and try to implement a few things yourself. Next, you purchase a piece of hardware and write a fully functional program.
The final stage above is an excellent time for you to start looking for a job as a PLC programmer. The reason being is that you’ll never have access to the same type of hardware at home as you will at work. It’s an excellent idea to spend some time programming a PLC connected to your laptop, but you need to see the world which involves actuators, valves, motors, sensors & of course operators which will be running your system. No virtual training can prepare you for this; it’s something you’ll have to deal with on the job.
The lesson here is that your goal should be to use the skills you’ve learned as soon as possible. If you’re going to learn for the purpose of learning, the knowledge will most likely go to waste.
Fun side note: I purchased a guitar in the hopes of starting to play. I’ve taken it out of the case 3 times in the last 7 years. Don’t let that happen to your 1000$ PLC/HMI.
PLC Programming Knowledge is Reapplicable Across Platforms
A big misconception among PLC programmers is that you need exposure to every platform in order to be competent. In other words, you can’t program a Siemens because you’ve only been programming Allen Bradley PLCs. This couldn’t be further from the truth. Most ladder logic instructions are exactly the same on every PLC platform. The only differences you should expect will come from the IDE layout, some of the configurations & how things are tied together. An experienced Allen Bradley programmer should be absolutely confident in his skill to transition to the Siemens platform if push comes to shove.
By knowing that the above is true, you can stay focused on the same platform and keep learning advanced concepts. If there’s a need for you to work with something else, your response should be that you’ll need a bit of time to get up to speed, but you know how to get it done.
If you are familiar with PLC programming in general, don’t let a specific platform discourage you from applying to that particular job.
Conclusion
Forces are a powerful tool which can be primarily leveraged during start-ups and/or for troubleshooting. It allows one to set input or output to an energized or de-energized state bypassing whatever logic is tied to it.
Within the industry, forces are being heavily utilized as patches for solving problems. The key to properly utilizing forces is to make sure that none of them are left within the program as you walk away. In case you need to temporarily force an Input or Output, you must remember to rectify the problem and remove said force.
