from the Automation List department...
Whats the Best PLC in the market?
PLCs and related questions. topic
Posted by Paul Chung on 2 July, 2001 - 4:58 pm
Whats the Best PLC in the market?
Hello, I'm from the Philippines, I just want to ask what's the best PLC in the market? Some say its SIEMENS, other's say its Allen Bradley, which is really the best? Have anyone of you used Tri-PlC? or IPM brand PLC? Any comment? And what's the best vis a vis price? Meaning, a good reliable PLC but yet inexpensive.
Thank you very much

Posted by Gruhn, Paul on 2 July, 2001 - 5:09 pm
What's the best car in the market?
What's the best PC in the market?
What's the best fax in the market?
What's the best color ink jet printer in the market?
What's the best computer projector in the market?

Get the idea?

That all can do pretty much the same thing (as can all the above products).
Consider other more relevant issues such as programming language, local
support / service, price, deliver and many other issues.

Paul Gruhn, P.E., C.F.S.E.
Siemens, Houston, TX

Posted by Dean Reimer on 2 July, 2001 - 5:10 pm
Talk about opening a can of worms.

I don't think you can say there is one best PLC in the market. Most people will tend to have experience with one or two types, and will tend to regard these with some preference because they are used to them and have developed speed and
technique with programming them.

There are PLCs that handle certain applications better than others. If you are controlling a small machine with 30 digital I/O, your definition of the best PLC is not going to be an AB PLC-5 or a Modicon Quantum. If you are controlling a chemical process plant with 10000 I/O, the best PLC is not going to be an AB SLC
or a MicroLogix.

Most of my experience is with Allen-Bradley gear. While I find it easy to use (I'm used to it after all) they are by no means leading edge in terms of development (AB is very slow in technical innovation) or price.

Ultimately there is no answer. You need to look at the application's requirements and evaluate the offerings from each supplier. The "best" choice is the one that combines the features you need with the right price and level of support.

Dean Reimer
Westroc Inc.

Posted by David Lawton Mars on 2 July, 2001 - 5:29 pm
dreimer@WESTROC.COM writes:
> Most of my experience is with Allen-Bradley gear. While I find it easy to use
> (I'm used to it after all) they are by no means leading edge in terms of
> development (AB is very slow in technical innovation) or price.

I'd disagree on this point. I reckon CLX is a very interesting development albeit a bit slow on customer up-take. I'd say CLX had some teething troubles when it first came on to the market but I think it's going to prove a massive success.
I agree with the general opinion that there isn't a "best" PLC, much as there's no such thing as a "best" anything, but give me AB over Siemens any day. I eagerly await an interesting response from all Siemens fans :)

Posted by jmGiraud on 2 July, 2001 - 5:13 pm
The most complete logical system I used to work with is an hybrid: loop/logic.
It's manufactured in Houston (Texas).
Name: Micon.
You will learn so much from them

Posted by Eminent on 2 July, 2001 - 5:32 pm
Hello Paul Chung,
We could bring all the PLC manufacturers together and say five clients for each manufacturer, and in the end we may end up with tons of comparisons and frankly no solution in sight.

Some of the factors that define a good PLC that I can type on the fly are:
1. Suitability for the service where the PLC is to be used.
2. Reliability (MTTR and MTBF values are good leads).
3. Price and price stability.
4. How open are the PLC protocols? Do you have to pay for the drivers?
5. Support for various programming tools.
6. Programming blocks that are available.
7. After Sales Support. this can be put in no. 1 slot in case you are new to PLC's.

I believe that LinuxPLC will become the best within some time. Chiefly because of its commitment to open source and because of the people behind it. Source being open bugs will get fixed faster.


Posted by Kamath RL on 2 July, 2001 - 5:34 pm
with 20 years of expirience in various brands of PLCs , i can say it is definitely SIEMENS S7 series.
Kamath RL

Posted by Hakan Ozevin on 2 July, 2001 - 5:35 pm
This question may be the opening of Pandora's box. :))

By the way there are quite good ideas here. But I think the answer to this question depends on the location you are. I mean: If you are in a country/city where you can take almost perfect support (excellent product/software support, 24 hrs spare part service, quick delivery), then the answer depends on technical details (and if you are not an end-user already, depends on the preferences of your customer). Even those technical details depends on your orientation. For example, I believe that Siemens PLC's are more easy to program for IT people, however AB PLC's are for EE (Some may disagree this). If you are in a country/city where you may have a problem for the a.m. services, then you have to choose a brand whose representative near you can give you these services better.

Hakan Ozevin

Posted by Kevin Totherow on 2 July, 2001 - 11:46 pm
Best for what? You have to say what is the best PLC for...

I can tell you definitively that the best PLC is the one that can do the job for the cheapest installed and configured cost and provide the reliablity and long-term cost of ownership needed in the intended function - unless your boss, or client, wants brand X. In that case, brand X is always the best PLC.

In some places Siemens was the best, and in others it was AB. In some places PLC Direct was best and in others it was a soft-PLC in a PC.

Kevin Totherow
Sylution Consulting

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