Types of PLCs

Hello,

I am a college student and very new to the concept of PLCs, and I was wondering how many different types of PLCs are there? What are the most popular? Are there some that are better than others? I assume part of it depends on what it is being used for. Any insight would be greatly appreciated.

Thank you

Can you define what you mean by "types of PLC's"?

welcome to the forum.

by types of plc's you mean brands, there is a lot.
Allen Bradley, Omron, Toshiba, GE, Modicon, Koyo, Square D, Mitsubishi, Siemens, Texas Instruments, and the list goes on. hundreds of them.

what brands are popular, everyone has their own personal preference.
the big question is where do you live, and what is preferred in your area?

I have only dealt with Allen Bradley (AB) for the last 15 years, the plants I worked at only allow that brand, we have multiple licenses for the software.
the plants I worked as before that was mostly Allen Bradley and Mitsubishi.
again, plant standards.

it all depends on the area you are in. at my current location AB has good service, I know of a location in Iowa where you couldn't pay the customers to take AB, their reps stunk and gave horrible service. so Siemens is the top dog there.

in your career, you will have to deal with many types of customers, customer requirements, and people, so you must learn to adapt.

remember to document everything, keep good notes, work with maintenance and learn what they know and can do. give them detailed prints of electrical, pneumatic, hydraulic schematics, give detailed manuals, detailed plc programs.
keep things simple for maintenance to work on issues.

hope this helps,
james

You can slice this cake in a dozen ways...

Basic info about PLC:
https://en.wikipedia.org/wiki/Programmable_logic_controller

You can divide it by manufacturers, operating systems, hardware architectures, programming standards, safety...

gmcmichael said:

Hello,

I am a college student and very new to the concept of PLCs, and I was wondering how many different types of PLCs are there? What are the most popular? Are there some that are better than others? I assume part of it depends on what it is being used for. Any insight would be greatly appreciated.

Thank you

Click to expand...

Obviously there are lots of brands. PLCs range in price from ~$100 for a CPU at the low end, to ~$10000 at the high end. Software is typically free for the cheapest controllers, but you need to pay for programming software for more expensive controllers. Smaller controllers tend to have built in IO, whereas more expensive controllers need IO cards added (often in remote panels). More expensive controllers are typically faster, have more memory, and support more complex applications.

All PLCs can do basic logic. Some have extra functions built in, for motion control, safety, redundancy, special communication, etc. In general, you get what you pay for, but people definitely have different strong preferences. I don't know of any players in the market that are entirely coasting and overpriced, if you see a product out there, there is probably at least some niche where it fits perfectly.

These days, almost everything communicates over Ethernet in some form or another. Older PLCs typically communicated over serial.

Has the British HNC degree reached the states?

Many countries tend to favor a particular brand for example the states tend to be mainly AB (Rockwell), Europe tends to use Siemens as their main brand & Asia Mitsubishi, Toshiba etc. In the UK AB seems to be one of the main contenders for the larger companies (probably because their roots lie in the US), A lot of equipment used in the UK tends to be made in western Europe i.e. Germany, France & Italy so very often Siemens (unfortunately the UK are now a nation of shopkeepers & service industries, however, there are some in the UK that are fighting back). So the answer is probably open, however I have been in the industry for over 35 years & in UK there tends to be a reasonable mix of most brands. On this site you will probably see many comments/suggestions about using a particular brand, this is because these people use them all the time and some will have little experience with other brands. Me I have no real favorites, they all have their good & bad points, some of the main factors I have used in deciding what brand to use has been the support, reliability and cost. Unfortunately some of the big boys are using rather extreme ways of marketing & supply to hold users to ransom, this is spreading and increasing the costs to the user industry. Unfortunately the trend nowadays is bringing new versions onto the market more frequently and making it less backward compatible (if you don't know what I'm getting at surf this forum for problems in upgraded software and older equipment).
Sorry my beef for the day.

Ronnie Sullivan said:

Has the British HNC degree reached the states?

Click to expand...

I'm from Southern Europe and had a similar question "Define what is a PLC." in an exam... which then made me realise it was essentially a way for the teacher to give brownie points to the students he liked best as it can be a one line answer or an entire thesis report.