Choosing the right PLC

As your in the UK, I would go with Siemens or Rockwell.

Routeco that distribute Rockwell are a first class and their tech guy is enormously helpful as is the range of stuff in stock that can be next day'd.

The downside is the price point at this current moment in time, hardware and software.
The software is nice and easy though..

Siemens on the other hand, are currently great value for money. The starter pack for the entry level PLCs and Screens is good value and comes with the software you need, to keep that updated on the level you need is around £200 per year.

The downside is they lack the enormity of a distributor of the calibre of Routeco, you have Underwoods or Parmley Graham as major players, but distributor support is less, that said Siemens Tech support is free and they are very good.

Software has a bit more of a steeper learning curve than Rockwell, but not much.

Both companies are so widely used, everything is Google-able.

I wouldn't even entertain Mitsi and Omron, bit players with bit player support and nightmare software.

I do not believe Mitsubishi software is a nightmare, I have used all versions from the old dos based through GXIEC & GXWorks3, yes like all platforms it's what you are used to, As I said before, I have used many of the better known platforms & fluent in most of them, I cut my teeth on Siemens & Omron becoming system integrator for both, I found Mitsubishi to be pretty easy to use, great range of PLC's integrated software that works well, I have had no issues installing the software (unlike RW & Siemens), GXWorks3 combines both Works2 & 3 that covers the older models (some still current) and their latest platforms. BPX & RS carry stock & in the case of RS, next day on the smaller stuff. Conversion between FX, A & Q series works a dream I have done many conversions very useful. But like any platform there are good & bad things and these vary depending on your view. I agree that Siemens support is pretty good looking at their website, not really used any support from any PLC supplier to be honest in my 37 years in the game apart from one experience with RW, this was awful even after spending over 50K & I took the decision to drop them in a big way.

I suggest looking at Schneider's M241 and M251 PLC. In my opinion they are offer more than the S7-1200 at the same price.
You get Ethernet/IP and Modbus TCP/RTU out of the box. The SoMachine (now EcoStructure) software is not expensive and you get Codesys which a very powerful and modern PLC programming platform.

kallileo said:

I suggest looking at Schneider's M241 and M251 PLC. In my opinion they are offer more than the S7-1200 at the same price.
You get Ethernet/IP and Modbus TCP/RTU out of the box. The SoMachine (now EcoStructure) software is not expensive and you get Codesys which a very powerful and modern PLC programming platform.

Click to expand...

But is M241 and M251 pogrammable with EcoStruxure? (found the answer, yes.)

Steve Bailey said:

As a new user the brand you pick is less important than the quality of local support.

Click to expand...

This statement has always bothered me.
Why is there need for support?
The documentation should be thorough enough to explain how the PLC works.

Peter Nachtwey said:

This statement has always bothered me.
Why is there need for support?
The documentation should be thorough enough to explain how the PLC works.

Click to expand...

Sarcasm? LOL, I hope...



With software like a Rockwell and their lovely help files. Where you lookup a field called [Reset] and the help file says useful things like "This is where you enter the reset". Or help files and other documentation that are 10 versions out of date.

Why is there need for support?
The documentation should be thorough enough to explain how the PLC works.

Click to expand...

If I had purchased one of your company's controllers and felt the need to call for technical support would I be told that you don't offer technical support because your manuals are all anyone needs?

Peter Nachtwey said:

This statement has always bothered me.
Why is there need for support?
The documentation should be thorough enough to explain how the PLC works.

Click to expand...

This statement bothers me more.

Finally from the programming side, higher level languages are appreciated. I come from a programming background and am quite familiar with C and the like, though I've done some practice on ladder logic in a simulator and found it quite understandable.

Click to expand...

Automation programming relies more upon a deep understanding of the process being controlled than upon prior coding experience.

My advice would be to hire an integrator with experience in creating control systems for your particular process.

Besides PLC programming, I have done and continue to do computer programs, starting with turbo basic, visual basic, C ++, Java, etc.

In no case I have considered using these languages in PLC programming, it is a very different world that requires another approach from the beginning, in which you have to use the programming tools offered by the PLC manufacturer.

Manufacturers make sure that you have to buy their software as the only alternative and these tools do not usually offer the possibility of programming in C.

In addition, the execution speed is very important in a PLC and for this a low level language will always be much faster

In addition, as already said, the first is to understand the industrial processes that you want to automate.

Peter Nachtwey said:

This statement has always bothered me.
Why is there need for support?
The documentation should be thorough enough to explain how the PLC works.

Click to expand...

I consider 'local support' to be an important factor in those inadvertent moments when the machine or process is down, and yes the customer didn't keep spare parts on hand.

I concur with questioning why 'local support' is important for system development. To me documentation is a big part of brand selection. While Omron and CX Programmer got a few black eyes in this thread, I've been using Omron extensively for over 12 years and probably have needed to contact support only once per year on average. This is not because I'm an amazing programmer, but rather I've found the Omron documentation to be excellent and thorough.

I've also used another common brand of PLCs that are mentioned in this thread, and have had headaches finding answers for multiple problems. And for this particular brand, we have top notch local support, but unfortunately the documentation is sadly lacking.

So I would suggest Peter's question is well worth considering...

I agree that good documentation is a must, I have been using Mitsubishi regularly over the last few years and on other occasions for over 30 years, Yes their documentation originally was poor, however, with the later GXWorks the documentation (like many others) checks the website for latest versions & if required asks if you wish to update, nice touch this, the documentation is very comprehensive & a visit to the website (a little bit difficult getting used to) there is all the documentation you could wish for.
I have little experience with support as I have never needed it, the local rep often called in & if I needed information would go out of his way to support me.
The only problem (and probably the same with all south east Asia) manuals there is a bit of poor translation (we call it chinenglish) but the examples in their latest documentation are pretty good. I suppose it is like any platform, they can all be daunting to start with, but practice soon overcomes these problems. I have not used Omron for a number of years but when I did again the support was reasonable.

How much documentation is enough?

The Siemen's Step-7 Pro manual download is 12,000 pages.

No other manufacturer has a manual over a few hundred pages, unless you combine Rockwell's many specific manuals into one.

I have just looked at the Mitsubishi E-Viewer system and it contains 5gb of data I think that is quite a lot.

parky said:

I have just looked at the Mitsubishi E-Viewer system and it contains 5gb of data I think that is quite a lot.

Click to expand...

Mitsubishi did excellent job with GX Works3. Documentation is upgraded cca every week and software cca every month or two. Upgrades are free of charge, unlike to Siemens and AB.
I did thorough comparation of Mitsubishi iQf and Siemens S7-1200 and Modicon M241/M251. All three have very similar configuration regarding IO's and options. On test of ruggedness and speed Mitsubishi was best. Schneider had best price. Siemens had cheaper analog inputs and outputs than Mitsubishi, but overall for any project that was more than basic it had highest price. For me GX Works 3 and GT designer were win win combination, specially due to excellent simulators. SoMachine (Codesys) was also good combination also due to Magelis HMIs which I do like. Siemens with their version incompatibilities and HMIs that I do not like is third option for me. I need to state that I do like Siemens online program change best.

#1. Goghie Could not have put it better myself, The only thing I would add is that The GOT's do not have much in the way of templates that work out of the box. There are a number of so called templates but these are nothing more than bitmaps you have to create things like multi state but it's not all that easy. I prefer the Beijers who at one time re-badged them for Mitsubishi great HMI's and I must admit I preferred the E series to the later versions.