what plc is the best?

[PLucas]

Reading the replies,

it seems to mean that Ron has got it spot on.

Just for the record, I think GE Series six PLC's are the best followed by Siemens S5, S7 200's and 300's.

Why?

Because I know series 6 like the back of my hand, and the only other PLC's I have worked with are Seimens S5's and S7's.

All down to personal preference.

Paul

 

[bentleya]

Terry,

It's nice to hear someone else likes TI. I have several of the old ones (305,405,...) but my favorite is definitely the 545 & 555 units.
I have to work on idec, GE, Modicon, AB, TI and several different lines within the same manufacture. The TI is the easiest for me to explain and teach our electricians to use.
I even have 8, or so, of the old CVU100's in use. They're a blast.
I don't even try to teach the programming on those (OIL).
I believe the Modicon (984's in use) is the simplest PLC on the market. Of course, don't plan on doing any rocket science with them!

 

[Tom Jenkins]

Otay, now I hab to tay tometing

Nif's comment forced me bandage my tongue and break the vow of silence.

First off, Nif, your market share arithmetic is off. In Europe you neglected Omron and Mitsubishi, which in my limited travels over there seem to have a small but significant market share.

In the US you neglect GE, Modicon (Schneider) Mitsubishi, and AutomationDirect. All of them not only have a measurable market share in the US, all of them have an increasing market share while Allen Bradley has a decreasing market share.

Furthermore, you don't distinguish between techinical merit and market share, which may be a result of technical superiority, or may be a result of marketing, or may be a result of local distribution, or may be a result of packaging PLCs with other parts of a broad product line.

Furthermore, you don't take into account the importance of technical support, either the manufacturer's or the local distributor's.

Furthermore, you don't take into accont application specific factors like communications, I/O count, specific process or sensor constraints, programmer's expertise, operator interface requirements, and so on.

There is no one best PLC brand, and there is no one best PLC model. I have my favorites, but they don't coincide with every body else's needs. An engineer must consider all of the above factors and make a judgement based on individual system considerations. The reassuring factor is that most of the major brands can do a good job with a reasonable committment of resources.

 

[TimothyMoulder]

My two-bits...

"Best" is also a subjective criteria.

Obviously, the PLC that can do only DC I/O is not as good as the one that does AC and DC. What if you want to turn on your house lights?

Of course, that's a bit extreme, but it illustrates my point. I've got about ten software packages on my compuker at the moment, about a third of them are DOS based. I can say, with some degree of certainty, that DOS based plc software SUCKS!!! And any PLC constrained to DOS software (B+R 2005 with an NC154 controller, for example, I have four of them to contend with) LIKEWISE SUCKS!!

Now, among windows programs, I like RSLogix500. It's easy, intuitive, and once you have a little experience, powerful. When you save a program file, it saves an actual, single file (unlike PicPro, which saves a whole host of function blocks, or VLC that saves about a million flow charts).

It works with enough hardware that you are almost always assured of finding something that meets your needs, and you can build on what you already know of the program, instead of a new set of commands and methodology ("Where the $%^%$ is the N/O Contact?!").

The only thing I don't like is the software extortion method AB uses to generate extra pocket change, and for that reason I'm phasing the smaller ones out and going with a different company. But I am happy to have "cut my teeth" on Allen-Bradley products, and would cheerfully recommend them to beginners. Also, I intend to use them in the future for any large-scale work that comes in.

So there's my vote - Allen-Bradley, for ease of use early on, and power when you're ready for it.

TM

(Let the egg-tossing begin!)

 

[GregPLC]

Modicon???

What is everyone's opinion of the newer modicon stuff? I learned on Modicon, using concept function block programming.....Now I'm learning AB PLC's. Why is there hardly ever any mention of Modicon on here?

Greg

 

[Peter Nachtwey]

Not So!

You can program using, STL,FBD,LAD,SCL....+ A few graphical languages.. and so on.

Don't you think that learning all those programming languages make the learning curve longer? Most people would consider the learning curve for STL steep. Most would rather programming in a higher language. Yet there is no easy way to do indirect addressing using ladder. There is an example of how to do indirect addressing using ladder on the disk that comes with the Berger book. In STL indirect address is easy.

ALL Commands can be used in eg. Ladder

Where is the JL or jump distributor instruction for ladder? The jump distributor instruction is the key to writing efficient state machines. I don't know of any other PLC has the abitlity to use jump tables besides the S7-300 or 400.

I can think of a lot more examples of instructions in STL that do not exist in LAD. I will be merciful.

 

[tomneth]

OK, I'll throw my $0.02 in. The first PLC I ever worked on was a Texas Instruments PM 550. I loved it. Then some more TI sequencers. Then a GE Series Six, not as much love, especially with PID loops, but didn't spend as much time on it. Then Modicon's 984, once you understand how the networks scan very user friendly. Then Siemens S5, more complex with STL, but try doing some of that with LL. And now throw AB SLC's into the mix, not as difficult as Siemens but still different enough to require a learning curve.

Of the PLC's I've worked on I liked the TI and Modicon the best but probably because the TI was my first and Modicon I've worked on the longest. They are all similar in function and in my opinion the most user-friendly PLC is the one you've worked on the longest and are most familiar with. Your employer will probably dictate which PLC you like best

 

[RRobbins]

Gota add mine too!
I have used them all and they all have a place. Depending where that place is. Some of the small bricks, no matter whose, they are are extremely fast, but limited communications and interfaces. For a small OEM or for learning PLCs they are perfect. Most of you guys only know ladder logic. The US is the primary user of LL is is loaded with overhead and takes a lot of programming to get anything done. I program in many languages, ladder is prefered by most maintenance people.
Mid sized PLC's are all pretty close, price and functionality. Higher end, give me Siemens, they are the ONLY one that can do hot-swapping between instructions. Most require the checks to be at the end of the scan. Easy to set up and extreamly powerful.
Profibus is my prefered distributed I/O network. At 12mb, it can handle remote analog I/O, faster than most PLC's analog in the local rack.
I think the TI545 and 555's were the most powerful "Process" controllers, because of their analog capability. Most other PLC's were designed around digital I/O.

 

[Terry Woods]

RRobbins said...

"I think the TI545 and 555's were the most powerful "Process" controllers, because of their analog capability."

Please don't put them in the grave yet. They are still supported by Siemens.

With respect to preferences, of the dozen-or-so PLC's I've learned, the TI was the latest (that sorta includes the S7-2XX). So, I've known and worked with others longer than TI, but, in terms of the design philosophy, and for my tastes (all in my mouth?), the TI wins hands-down!

Even if it doesn't meet all of Peters' needs.

bentleya said...

"Terry,

It's nice to hear someone else likes TI. I have several of the old ones (305,405,...) but my favorite is definitely the 545 & 555 units.
I have to work on idec, GE, Modicon, AB, TI and several different lines within the same manufacture. The TI is the easiest for me to explain and teach our electricians to use.
I even have 8, or so, of the old CVU100's in use. They're a blast.
I don't even try to teach the programming on those (OIL).
I believe the Modicon (984's in use) is the simplest PLC on the market. Of course, don't plan on doing any rocket science with them!"

I still have a couple of 405's as well. We recently got rid of the 305's.

I certainly agree that the TI is easy to explain. I like the way that it appears to use a "flat-file" system. Damned near everything is available at the top level (one exception being Constants-K... easy enough to get around, though). Sub-Routines, Special Function Programs, All Data, and... are available at anytime. This makes for very easy (though, incredibly stressful) On-Line Programming. No need to shutdown the whole system just to fix a small problem.

The "flat-file" nature makes it really easy to explain things in terms of a desk-top. I don't have to use a "File-Cabinet" explanation. Everything is above board.

I'm using TiSoft and CVU10,000. Have you noticed that in CVU you generally can use only two colors to indicate the status (either ON or OFF) of a graphic symbol? I found a way to use as many colors as I need.

So, I can show that...
the motor is ON,
the motor is OFF & Available,
the motor is OFF & Not Available (as in "Locked-Out"),
the motor is in Stand-By,
the motor has FAULTED.

That's five colors for the same figure.

Might not sound like such a big deal to some of you guys, but it is to CVU users!

---

...SLAMMED... ???

I didn't see anyone get slammed.

---

Ken Roach said...

"Terry, that was admirable. Your succinctness serves your point well."

Believe it or not, Ken, I really do try to follow my Life-Philosophy.

Thanks.

 

[RRobbins]

Sorry Terry, you are right. I am currently helping a customer with a project (water treatment) with all NEW TI parts. The new TCP CP and NEW configuration software is sweet. There is also a new OPC server package for the 545/555's. The OPC server don't need Tisoft or Soft Shop to configure, only the TCP address and memory type and location (eg. V1000 or WX200). You do need the latest version of SoftShop to utilize the expanded features in the 555-1106 processor. What I meant was, 10 years ago, the 545's were ahead of their time!

 

[Peter Nachtwey]

You don't always get what you want, but you get what you need.

Even if it doesn't meet all of Peters' needs.

You should know that we have sold more product that works with the TI545/TI555 than any other PLC. It has satisfied the need for a lot of my customers and therefore mine. We have a TI525, TI535, 2 TI545s and a TI565 with remote base controller. We have put a lot of resources into support our products in the 505 platform.

I don't argue which is best. I state features and let others decide what is best for them. My 'favorites' are those PLCs that communicate well with our product and require the least amount of tech support from us.


I certainly agree that the TI is easy to explain. I like the way that it appears to use a "flat-file" system. Damned near everything is available at the top level (one exception being Constants-K... easy enough to get around, though). Sub-Routines, Special Function Programs, All Data, and... are available at anytime. This makes for very easy (though, incredibly stressful) On-Line Programming. No need to shutdown the whole system just to fix a small problem.

The "flat-file" nature makes it really easy to explain things in terms of a desk-top. I don't have to use a "File-Cabinet" explanation. Everything is above board.

So is the "flat-file" structure best for you or best because it is easy to explain to someone else?

For me S7 data blocks or Control Logix objects with tag names are best, but then I don't have to explain this to an electrician like you do. This is similar to the same reason I like AB MSG blocks. MSG blocks are not faster than Profibus DP, but they are easier for my customers to configure and program so it is easier for me or our tech support to explain.

Obviously, our definition of what is best is tempered by pragmatism.

---

...SLAMMED... ???

I didn't see anyone get slammed.

---

Me neither.

Kalle, I may not have mentioned your favorite PLC because I don't have your type of PLC. I actually have all those PLCs I mentioned and more. I didn't mention GE9070 or Reliance Automate, but those are pretty much ancient history. We need these PLCs for testing our products, writing example programs and supporting customers. I sometimes refer to my office as the electronic zoo. A spare SLC5/04 recently got pressed into service doing traffic lights in a co-workers class project of all things.

Sort of off topic. One of the reasons AB sells so much is that the AB distributors and AB support the local education systems. The instructor works for the local distributor and brain washes a new group of students every quarter. What PLC do you you think these student will like best? As someone above stated the best for them is the PLC they know. That is strategic marketing.

 

[The real deal]

SLAMMED... ???

What are you doing, sucking up? Anyone can fall in line and be the same!

 

[Phil Melore]

I know who you are...

What are you doing, sucking up? Anyone can fall in line and be the same!

Ok Mr 'The Real Deal'. It took me a while to do the detective work... but I know who you are now.
Since I see you generally post under another user name I'd ask that you behave and use your regular username.

I'll go ahead and disable this 'real deal' account for you... since I'm sure you have no need for it anymore.

Now play nice and this will remain 'our little secret'. utoh

 

[TimeFluxCap]

mocrothene

Ive worked with both AB and Siemens but they can be expensive for software if you just want to play around. Try
http://www.crouzet.com/corporate/m2/uk/index.cfm
and check out the Crouzet Millenium II. You can download the software for free and have a play.

Have fun now!

 

[Terry Woods]

Peter said...
"You should know that we have sold more product that works with the TI545/TI555 than any other PLC."

Yeah... I know... I just didn't do a very good job of saying what I meant.


In my poorly written original post...

---

With respect to preferences, of the dozen-or-so PLC's I've learned, the TI was the latest (that sorta includes the S7-2XX). So, I've known and worked with others longer than TI, but, in terms of the design philosophy, and for my tastes (all in my mouth?), the TI wins hands-down!

Even if it doesn't meet all of Peters' needs.

---

Second try...

---

With respect to preferences, of the dozen-or-so PLC's I've learned, the TI was the latest (that sorta includes the S7-2XX). So, I've known and worked with others longer than TI (and S7-2XX), but, in terms of the design philosophy, and for my tastes (all in my mouth?), the TI (and S7-2XX) wins hands-down!

Even if it (the S7-2XX) doesn't meet all of Peters' needs.

I said that only because, in the past, you have described various problems with the S7-2XX that make it harder for you to do what you need to do. That's all I meant to say.

---

Terry said...
I certainly agree that the TI is easy to explain. I like the way that it appears to use a "flat-file" system. Damned near everything is available at the top level (one exception being Constants-K... easy enough to get around, though). Sub-Routines, Special Function Programs, All Data, and... are available at anytime. This makes for very easy (though, incredibly stressful) On-Line Programming. No need to shutdown the whole system just to fix a small problem.

The "flat-file" nature makes it really easy to explain things in terms of a desk-top. I don't have to use a "File-Cabinet" explanation. Everything is above board.



Peter asked...
So is the "flat-file" structure best for you or best because it is easy to explain to someone else?

First...
I didn't claim it was "best"; I claimed it was "easy".

Now...
The answer to your question(s) is Yes... Yes, on both accounts.



Peter said...
Obviously, our definition of what is best is tempered by pragmatism.

To which I say...
I agree. I sure find it a lot easier to communicate using English!

I was once faced, at the last-minute, with creating a Spanish Interface. I broke out my "Spanish Made Easy" book and an "English-to-Spanish Dictionary". I never did find out exactly how it turned out... but I did get a note in the mail from the customer expressing their delight in the humorous interface. (The screen messages were eventually rewritten.)