PLC brands comparison 3

This isn't a fair contest. What do you mean, "...rack type being out of scope"? That eliminates many good ones.

What's the application? Is a faster PLC better than a PLC with more memory or capability? How many I/O? What type?

How about technical assistance and on-site service capabilities? Or warranty? Are they important?

You've left yourself open to way too many variables.

Look at sales results for the most popular (I think probably A-B and Siemens).

Here is some "backing" for you of what you are seeking.

Results:

You can vote here if you want, but there is enough numbers above to show you that Allen Bradley is a pretty clear leader.

Chris Elston
Automation & Controls Engineer
Download Sample PLC Ladder Logic Code
at MrPLC.com

I think that most people will argue their favorite as the best thereby rendering any real net gain of insight rather mute; because, many of us simply associate our first experience with the best and never objectively consider alternative systems on par with others. This phenomena is called impressioning and is what causes a duckling to impute maternal charge to the first animal it sees upon birth. As regarding, ease of use, our first experience generally wins hands down, because our learning ability is diminishing as we age, there are lots of names for this condition.

I use all the systems in the survey cited above because my customers all have their "best" ideals and I'm spending their money to make them happy. When I am spending MY money, we use a different "best" because I want maximum punch for the dollar spent without giving up the required performance in field.

I teach PLC system design on about 12 different systems and whatever a newcomer sees the most and learns the first is "best" to him/ her every single time.

This is how I would pick the best in a contest. Take a novice and give him a real world system to design with all the revelant literature from each of the surveyed systems. the one that he can quickest satisfy the given requirements is the best for that particular application in that situation. Of course, that is spoken like an automation contractor, which I am. Each system is targeted to some end and probably excels strictly in that end or they missed their mark in development.

That's my 31/2 cents worth!!

As an aside, I reviewed the survey and have concluded that the best plc is probably not what people are voting in this anyway. In east Asia, I would expect to see %33-40% Omron market share in numbers, In Europe and ultra heavy industries, like STEEL and Aluminum, I would expect to see
around %40 Siemans market share. The survey looks like small to mid-range manufacturing companies talking about what their BOSS had installed in some integrated equipment when it came in the plant. I think people are simply naming what they have seen in a cabinet. Many systems with large followings such as Klockner Moellar and Reliance aren't even listed and I see this in as many places as Allen Bradley in Arkansas.

For small, powerfull, cost efficient PLC's, try Automation Direct,(
Small form factor
Easily configured
Power efficient
Wide range of sizes for required use

No, I am not a salesman, just an observer. We have used several PLC's in our company, and the Automation Direct PLC seems to fit well in the small to mid-range applications.

I see by your reaction, gentlemen, that I have to clarify my request a little.

I clearly asked not to use personal preferences as arguments.
Neither do I think that sales statistics reflects the brand/model quality or value.

The goal of this poll should be exactly to reduce the effect described by Skills, when the first used is considered the best.
Another phenomena is what I call the brand preference inertia.
And very often the reason is that your information about another brands is obsolete.

The reason to evaluate only single-unit PLCs is that I meant small-to-medium projects (128-255 I/O max) and reasonable price (under $1500, excluding software).
This is the class of AB Micrologix 1500, not SLC.
The scan time is not a big consideration, though may be an argument for the choise.

Ideally users of two or more brands should compare them and indicate advantages and disadvantages of each vs anothers.
By the very nature of such method, a user of only one brand has nothing with this poll as an author.

Best regards

I'll start myself, comparing AB Micrologix 1500 to Mitsubishi FX1N.

Hardware.
Both are single unit expandable PLCs.
The hardware is very similar by price with more I/O extensions, but the FX1N tends to be less expensive for less I/O numbers, especially without extension.
Maximum number of I/O is 255 for FX1N and 156 for ML1500.
The advantage of ML1500 transistor main unit is several relay outputs, while the FX1N main unit is homogenous by the outputs type.
The FX1N main unit inputs are configured as sink/source all at once, while the ML1500 inputs are grouped in several groups.
The largest main unit of ML1500 is 28I/O.
The largest main unit of FX1N is 60I/O.
The ML1500 largest extension modules are: for ML1500- 16I/O each, FX1N- only 8I/O each.
FX1N exists in AC powered version.
Also, FX1N of any type features a built-in stabilized 24VDC/600mA service power supply. With AC powered PLC this may eliminate a separate power supply for small project.
The FX1N has an inexpensive option of the programming port duplicator card, which allows the PC to be connected without disconnecting the MMI unit, if any.
FX1N high-speed outputs are isolated and may be used as sinking or sourcing each.
Both models feature two analog setting potentiometers on the main unit.
The special modules choise looks little wider for FX1N.
Expect the FX1N with extension modules to occupy more rail than ML1500 when extended over ~128 I/O.

Programming and sofware.
The programming software convenience is strictly individual, but the Mitsubishi software is less expensive and not copy protected.
Even the legacy DOS software may be used for FX1N programming.
The Mitsubishi software does not require additional communication driver to communicate with standalone PLC, while for the Allen Bradley you need the RSLinx installed and configured.
Mitsubishi programming cable is expensive, but I suggested a link to the inexpensive replacement in one of my posts on this forum.
ML1500 has NO online programming or editing- a big inconvenience during debugging!
FX1N may be programmed online except for interrupts.
The ML1500 has bigger choise of internal devices (T,C,B)and their quantity is virtually unlimited (limited only by the PLC memory), all the devices may maintain their status with power off.
The FX1N has limited quantity of each type device, each timer resolution is predetermined.
Only part of the FX1N devices maintain the status with power off.
On another hand, FX1N features 32-bit counters, lacking in ML1500, and almost any instruction may be defined as 32-bit.
ML1500 instruction set looks wider for sophisticated math calculations.
6 high-speed inputs may be assigned to interrupts on FX1N versus 4 on ML1500.
Both feature 2 high-speed outputs (frequency pulse train or PWM each), but FX1N allows more control over the frequency pulse train, like direct frequency change on the fly.
Unlike the ML1500, the FX1N has no forces that can override the program execution- any device may be directly written online; it will be, however, processed according to the program logics and may be altered by the program at any time.
FX1N outputs may be altered online when the PLC is not running, unlike the ML1500.

Well, enough for the beginning.
Correct me if I forgot to mention something important.
And ask questions about FX1N, if any.

Best regards

I have experience with the following brands and models of PLCs. They are Allen Bradley PLC 5, SLC 502,503,504,505,Micrologix 1200, Ge Fanuc 90-30,Omron CS1-G,
Modicon compact,Modicon Momentum,Automation Direct Koyo 305
I find The allen Bradley brand of PLCs to be fairly easy to program. The programming software (RSLOGIX)is very well structured. Programs can be generated very quickly as vertical and horizontal lines are automatically generated.
there is no need to insert extra rows in order to create branch instructions. The I/O tables are automatically generated after the PLC back plane is configured. Generation of bit tables is easily accomplished. I love the manner in wich Allen Bradley addresses I/O. It is extremely intuitive. for example an input address I:1/0 is an input address denoted by the letter (I) that resides in slot 1, terminal 0. Other PLC manufacturer's such as GE Fanuc,Modicon,and kOYO use the following. Where is the logic in these conventions?

%I0001,10001,X1,etc.

One of the aspects I do not like when using Allen Bradley brand PLCs is the fact that many programming devices such as the PIC,PCMK card, and others are available to interface a PC with the PLC. Other PLC manufacturer's provide only a serial cable used to interface the PLC with a PC, thus the complexity involved with setting up a communications driver is non existant. Just give me only one methosd to communicate between the PLC and my laptop!

However the fact that Allen Bradley provides a host of communications drivers for communicating with ethernet device net and such is very nice, as it is integrated into RS Linx. With other PLC manufacturer's these drivers must be purchased sepearately.

It is also failrly easy to make online changes to a program.
When using the PLC 5, SLC 503,504, AND 505. The Micrologix 1200, and SLC 502 PLCs do not allow online changes.

I/m going to stop for now. I have to get ready for the work day. I will dicuss the likes and dislikes of the GE Fanuc PLCs in my next post

bets regards, plcsavvy.

It would seem from "xyzz" posts in this thread that he is trying to get us to "vote" for the Mitsubishi FX1N.

As an OEM we have used numerous PLC's for our customers and there is no doubt that each have there place for many of the reasons specified in the above posts.

The market for the smaller PLC's [rackless/shoebox w-expansion]is extremely competitive. They all have very similar capabilities in hardware and while the instruction sets may be different between manufacturer they can DO the same thing. I would suggest that hardware COST is now completely irrelevant.

The cost of programming/documenting/maintaining the PLC software is the key factor. We have standardized PLC's from Rockwell Automation NOT because they are necessarily the best or most advanced units but because their software IS far ahead of ALL the competition.
"plcsavvy" notes it is very well structured, intuitive. I would add that the ability to modify file types and size in memory offers extraordinary flexibility to the programmer versus fixed memory locations found in most other PLC's. The ability to define each machine function in its own separate identifiable file sure beats one huge long ladder diagram.

Yes RsLinx does stinx. But let's face it, when you get used to it it works fine.

My biggest gripe is the inability to do on-line programming changes on the MLX1200 or MLX1500. "xyzz" definitely is right on that one.

I'm wondering if those parties heralding the intuitiveness of RSLOGIX have used DIRECTSOFT to a large degree. I use both, albeit, I don't use RSLOGIX as much and I find it uses
unusual paradigms for memory. I develop a lot of microcontroller system pic, AVR motorola, and intel stuff and DIRECTSOFT appears to match most of the software development for computers, regardless of use. With regards to PLCSAVVY's observation of memory/ I/O reference, it seems that DIRECTSOFT uses the convention used in most any microcontroller development system. X's are input and Y's are outputs is fairly standard algebraic notation based on the cartesian system.

Both systems edit fine I suppose, I used both in parallel
to pick the most efficient, quess?

The points QUIPPDUDE makes are interesting; but, I've never found a need to adjust memory size of resources to cause me much trouble because DIRECTLOGIC provides enough of all these resources you don't have to dink with it in the first place, DL systems aren't stingy like that, which is really why that ability is required anyway!

As regards his statement about long ladder programs being cumbersome, That's why STAGE programming is provided, so you don't have them anymore if it is applicable.


Software wise, DIRECTSOFT is way ahead of any development software under $10,000 with the exception of Think-n-Do.

Hey, you might get a better response if you asked which was the WORST PLC.

I'd vote for the Honeywell LogicManager, IPC-620. Most expensive and weakest program I've seen. I don't think they make it anymore (Honeywell switched to the A-B Contrologix platform). Thank goodness!

Well, many thanks to mister X, he really worked hard on this one.

One thing that belongs to the past is the "No Licences" feature of GX-Dev. The newer versions come with a site licence. You install it and then you need to supply them with a key generated by your PC and then they give you another key to unlock the software. What a pain!

At least one could copy the master disk of AB.

I still will use version 9.11B and older for they still can be copied. Hey, I have a laptop too!

I was out of town a few weeks ago and in a hotel room I installed this new GX-Dev. version...

Since the software detected that I had GX-Dev. installed earlyer in my laptop, it locked the program and I could not use it anymore...

The features I like about the Fx serie is the ease of use and programming.

Want a OSR, add P to the function. That is nice.

The down side... If one has never established the configuration of an special extension module... the writting and reading of buffer meory areas in those can be a little tricky. I get many calls about this.

Also the way that Forces (Mitsu) do not work when the bit is in the program is a pain.

As for OMRON, another brand that I use, I really kinf a like some of them functions. The table compare is very good.

IMHO

The best printing goes to AB (Zoom + many extras)
The best Online monitoring goes to Mitsu (fast)
The best software to program via the web goes to Mitsu (almost not com loss)
The best software goes to AB (unbeatable for thos shoeboxes)
The worst software goes to AB (don't tell me RSLinx of not RSLogix) the fact that they are separate is irrelevant.

As promised, here are my thoughts on the GE Fanuc 90/30 PLCs. I find that the versa pro software environment is for the most part well designed. I like the fact that you can issue commands (pneumonics to create ladder logic.This speeds program development. Once learned your fingers can fly across the keyboard. Some of you may say that you can do this with Allen bradley PLCs as well. I have to agree, but not with the ease and speed of versa pro.I praise Ge fanuc for their one serial interface for communicating to the PLC and laptop computer. Only one driver to configure!
One major complaint I have with the GE Fanuc PLCs is the use of the words store and load. These are used to down load and upload. Don't ask me what each means. I can never remember and always need to look for the meaning in the help files,if it has been sometime since I last used a GE Fanuc plc. Another complaint I have is the fact that Timers and counters automatically encompass three consecutive registers. One register is used for the accumulated count, another for the preset, and another to address the counter.
Believe me it can be a major pain in the butt, if you use these registers elesewhere in your program (overlap). I do like the plug in communications modules that GE Fanuc provides. there are so easy to configure and very robust.
Getting the software to print a program that can be read can be a daunting task the first time around. After that it is a piece of cake.
All in all I like using the GE Fanuc PLCs.
Modicon however is a different story.

I do use Direct Soft 32 and Skills is correct that the I/O addressing scheme follows the convention used by most microcontrollers as does the use of watch windows or in microcontroller terms the watch directive. I too design microncontroller related devices.

But let me ask you a question. Can you. using other manufacturer's PLCs, know exactly where to look on the PLC for an I/o point that is addressed as x10 or y13 without first referring to an electrical diagram?

You can with the Allen Bradley PLC.

best regards, PLCSAVVY

Those are great points made by plcsavvy, and I got a great deal of insight into fanucs software development systems. I also had an epiphany as I read it. Angels didn't come down and dance around my head; but, I did see something cool. In looking at different peoples preferences, I saw why 2-3 different software tools would gather different types of people. Each of these different systems are designed to appeal to different needs.

Your favorite plc system is dependent, to a large degree; on what else you do, where you do it, and your primary focus. I spend around 30% of my time designing microprocessor systems for hot rod cars and such. These embedded tool suites all condition you a certain way.

As I read the above statement concerning the association of a program element with a rack slot, I agreed that some are far more direct in presenting that info; but, from a development side don't value that feature.

I had thought, GEE, that's right; but why would you care unless you were maintaining someone else's design.
I configure and designate all memory variables, accum, timers, counter, constants, and I/O points and words, before I even know how I'm going to write the procedures. That's the way most any microcomputer programmer would do. In 2 days I couldn't easily tell you where clamp_valve_1 is connected to the rack. At this point, I don't care! I'm going to treat it the same regardless. When I'm performing troubleshooting, I wish for more convenience!

Microchips aren't slot oriented and worrying about physical location gets in the way of rapid development. Just as the AB ControlLogix system allows someone to write control software that doesn't even know what kind of cards, racks, or slots are available/ he just uses data/ I don't even think of the way to find that point then. Now, when I have to replace a broken wire.... It's a different story.

This response is limited to a the programming of a few of the brands that I have worked with over the last 20 years or so, so probably completely off topic!
The examples are all 'old' and to be honest I have not seen a great improvement in capability with the newer systems.

Allen Bradley (2/30 was the first I used, 1983ish)
Fantastically powerful ladder diagrams, IF you use the advanced instruction set. The brilliant idea that you can use equivalent instructions on bits, bytes, and even arrays.
Design the data tables right and the code can be very fast and small and powerful. The secret is in the data structures and the advanced instruction set.

Siemens S5
Huge flexibility - for example Function blocks make it possible to write your reusable standard modules that can be instantiated in higher level blocks.
STL is worth learning. It can approach assembler - good if you like to code at the low, fast level.

Texas APT
Almost object oriented higher level environment that preceded IEC1131/3 by a decade. Great for control loops and SFC's. Dont mess with the ladder that APT generates.

ABB Sattline
(It was a PLC when I first came across the company)
More object oriented than any control system I have ever worked with. Where is the global tag database? Buried in the objects.
But, create a control object (with it's graphics/HMI) and it can be replicated wih a few clicks

Here are my thoughts concerning the use of Modicon PLCs.
the types I have experience with are the compact and momentum series. First let me say that the compact is a rack type PLC and the momentum is not. The programming software I am accustomed to using is PROWORX NXT. This is my least favorite PLC programming software. This software is the most unfriendly and poorly laid out PLC programming software I have ever encountered.To start with, when enetering ladder logic, you must drag and drop every signle instruction, including,horizontal and vertical lines! Can you say very slow program development? Another feature I hate about the sofware is that when using a momentum PLC, the serial drivers required for communication between a laptop and the plc do not function correctly. Once online with the PLC, the driver will lock up your computer with any attemp to perform a search or simply scrolling through through your ladder program. The only method of communication that works is a modbus plus network. For this you need to purchase a $1000.00 MBx pcmcia card, modbus plus cable, and either t-taps or modnus plus 9 pin d sub connectors. Take it from me the t-taps are a major pain in the arse! Sorry guys there is no driver available for the wIN 98 operating system. GOOD thing I just received a new laptop with XP pro!
Another complaint I have with this software is when dealing with modbus plus, it is possible to send a program that is meant for plc 2 for example to plc 3. Imagine the head aches resulting from such a situation as this. This situation is worsened when performing a read from the wrong plc and writing over an existing program written for a separate plc on the modbus plus network. A word of advice " make copies". Wouldn't it be nice if the folks at schneider automation would have provided a program compare to prevent such an impending disaster. The point to remember with modicon PLCs is that you can buy better but you won't pay more. Another major complaint I have with the momentum PLCs and the use of proworx is that the i/o adresses and bit mapping is reverse of what you would normally expect. For example the top most input on the first 16 point input card of a momentum plc is addressed as 10016 not 10001 as you would expect! What a nightmare it was to discover this interesting feature. The only solution at that point was to renumber the I/O addresses on the electrical schematic and change the descriptions in the plc using the global replace feature. By now I am sure you are convinced that I dislike using modicon PLCs. best regards, plcsavvy

I've noticed noone has offered their thoughts of Keyence and the Visual PLC. Are there any users here that view Keyence as being out front with some of their innovations? I've only used these once; but they don't give up much to anyone else that is out there. I've also noticed that noone has cited IDEC as being the best brick, while I don't care much for these, I expected some people to. I'm going to say that, for my purposes at the moment, the DL205 family and more specifically the DL240 processor is the best small size plc I've ever used. Yes, there are other companies that may offer some feature that it may lack, today, but, seriously, if it was important to the project agenda and the realization of our goals, we'd go get one of those. The DL240 can do anything that I've ever seen a small plc do and much more.

The limitations that exist in it merely provide a market for its big brother, the DL250. At $259, I've never even heard tell of a plc that alleges to have the backbone, and sheer power and speed it has. Try 4 autotuning PID loops that run on the processor, 7.6K ram, floating point math, PID fill-in-the-blank profile generators, High-low alarming without code, configurable drums, ability to run 7 remote racks? Any takers on a sub-$1000 processors with similar capabilities?

I have had experience both in programming and specifying numerous brands of PLC's including Siemens, Omron, Mitsubishi and have had plenty of opportunity to compare them to many others. While it isn't a shoebox micro the very best I have worked with and specified is the Giddings & Lewis MMC and PiC series. One software application for all Plc's, backward compatible with earlier versions. MMC starts at ~64 I/O and 2 axis true motion control including circular interpolation, function block programming, expandable to ~3000 I/O using digital and analog block I/O. Ease of programming as described by hardcore A-B and other users. They can support up to 32 servo axes complete with fast inputs. Not cheap but great in terms of performance. Plc's are good at controlling machines but generally come up short in motion applications. G&L on the other hand is an excellent motion controller that can also handle machine control. There is a difference.

Correction.
I made a mistake in my post, the maximum number of I/O in FX1N system is 128, not 255.
Sorry for desinformation.