Why do you pay for PLC programming software?

M

Michael Griffin

In reply to Curt Wuollet:

With respect to what is the essential difference between a PLC and a PC, we had a discussion about this point on this list back in 1996 where Dick Morley (considered by most people to be the "father" of the first PLC) had the following to say about it: "I guess that the original concept of a PLC is that it is programmed with proprietary languages with proprietary tools and controls I/O through a proprietary protocol or bus system. It was even then a computer, but was not called that since it might scare off the user base, since they were not very 'computer literate' at that point."
 
C
Hi Michael,

I was speaking to reliability in that context, but the "just add ladder" system was and is a great help, to a point. And I, for the most part, can empathize with people who just want the simplest way to instantiate logic. After all, I never set out to become a programmer, it's what I needed to do to get my hardware to do anything useful. As far as it goes, ladder on PLCs is great and much, much easier than when I was writing in assembler or even machine code to make a microprocessor and some other chips test things. And it's pretty straightforward using graphical tools with ladder diagrams, possibly the easiest, most intuitive thing for a logical mind.

But then I used the existing tools on some very large and complex systems. Ladder logic is not for big programs, IMHO. It gets really hard to remember a few thousand lines. And then there were many blocks of IL. Guess what? IL is just a little worse than assembler. I was back to programming on my hands and knees. For a system of that size, well-structured C or Pascal or just about anything else would be easier to understand and work with than the "simple" PLC program. Add in a couple modules that are actually programmed in C and where is the advantage that PLCs provide on a small scale? And for C, all I need is vi. :^) At some point, you are going to need to become a programmer to deal with large systems. Once you have a library built with the low level stuff, there's not much difference in the complexity and code is at least as easy to read. If you're not scared of computers. :^)

Regards

cww
 
There is no comparison between a PLC & DeltaV. If you do not care about your process disruptions and process variability, then the loss of money does not matter to your company, then go with a PLC.

DeltaV will increase your production and keep your process running more reliable and reduce process variability in the product. This is what makes Companies money and not cutting corners with their control system operating the process.

All I can say to you is, bring it on, but you will never even touch DeltaV.

Ken
 
J

James Ingraham

A awful lot of posts in this thread say something like "Good software costs money to make, you idiots! You don't expect an accountant to do your taxes for free!"

Curt has pointed out that there are counter-examples. An awful lot of the Web is running on Linux-Apache-MySQL-PHP (also known as LAMP). The GNU Compiler Collection (gcc) is in extremely wide use in an extremely wide range of applications. But let's but aside the viral, communist, whack-job GPL / FSF stuff for a moment.

Here's a partial list of development software that for-profit companies give away, with or without the source code:

Sun:
-Java Run-time Engine (JRE)

-The Java Developer's Kit, containing the JRE, compiler, run-time, debugger, deployment tools, and more. (Solaris, Linux, Windows, and Mac)

-NetBeans Integrated Development Environment. (Anywhere Java runs)

-Compilers and other dev tools (C, C++, and Fortran) for Solaris and Linux.

-The Solaris operating system.

IBM:
-Lots, but most notable is the Eclipse Project(a clever dig at Sun, if you'll notice). At it's heart an IDE, Eclipse is so big now it's hard to describe. Other companies also contribute finacially. (Windows, Linux, AIX, Solaris, HP-UX, Max)

Microsoft (yes THAT Microsoft):
-Visual Studio Express Edition for C++, C#, Visual Basic, etc. (Windows only)

-.Net / Common Language Runtime (CLR) (Windows only)


The Java Virtual Machine (JVM) and the CLR are at least as complicated as the internal software of any PLC.

Would anyone like to claim that ANY industrial automation software they have EVER seen is superior to Visual Studio or Eclipse?

Oh, another thing. I have dozens of routers, wireless access points, and stand-alone print servers they I deal with. EVERY SINGLE ONE OF THEM has a built in Web page for configuring and monitoring, without needing a special cable or special software.

The idea that "Nobody makes software for free" is patently false.

-James Ingraham
Sage Automation, Inc.
 
That statement is not verfiable. DeltaV system 'can' be very good, but so can well engineered PLC systems.
The real issue imho is the quality of the application engineering - the platform is less important in my opinion. And yes it is just as possible to make a complete mess of DeltaV projects as it is with PLC's.

Francis
www.controldraw.co.uk
 
M

Michael Griffin

In reply to James Ingraham: To make a few minor corrections to some of the statements you made:

- Linux, Apache, GCC. Most of the active developers are paid by large and small companies (IBM, Intel, HP, etc.) to work on them.

- MySQL, PHP. MySQL is owned by MySQL AB. The main backer for PHP is Zend Technologies, whose other products are based around it. The main developers are employees of these companies. Having a "free" product does not preclude basing a successful business off it.


Eclipse is probably the best example of what you are trying to talk about. Most companies creating development tools for large scale software development base their products around Eclipse. Because the base Eclipse system has a free license, no one company can take control of it against the will of the other parties. This means everyone's interests are equally protected while they can still compete against each other on a level playing field. The Eclipse license allows these companies to produce their products as proprietary plug-ins (i.e. Eclipse itself is free, but a lot of Eclipse plug-ins for special functions are non-free).

Contrast that with Microsoft Visual Studio, which is a proprietary product controlled by a single company (Microsoft). There are companies producing add-ins for Visual Studio, but Microsoft can pull the rug out from under any of these companies at any time if they feel their corporate interest is better served by this (as happened recently for example to a small company producing unit test systems). Basing a product on Visual Studio is inherently risky as you are essentially handing over control to another party whose interests may not be the same as yours.

From the investigation that I have done, I believe that it would be possible to produce a PLC programming system as a set of Eclipse plug-ins. A ladder editor would be a plug-in, as would cross referencing, compiling, downloading, etc. An IL editor might be just another syntax for the regular editor, or it might be another
plug-in. CVS (or subversion, or whatever) integration would be already present (etc.).

There is nothing to stop any PLC vendor from deciding to base their next generation programming software on Eclipse. They don't have to get anyone's permission to do this; they can just go ahead and do it. There is also of course nothing to stop them from charging for each
plug-in. However, it would open the market more to third party plug-in providers or free plug-ins, so in that sense this would probably be a step forward.
 
M

Michael Batchelor

Francis is absolutely correct on this one. I have installed PLC based systems which have stayed up for years, and I'm currently quoting to
*REPLACE* a DeltaV system with an Allen Bradley SLC500 system.

Now, I'll grant you that the DeltaV system was completely screwed up from the the beginning, and the guys who put it in were out of their league. But still, the customer is about to have a fit to get rid of it, and I'm certainly not going to risk the job by quoting him something he doesn't want.

--
Michael R. Batchelor
www.ind-info.com

Industrial Informatics, Inc.
3281 Associate Dr.
N. Charleston, SC 29418

843-329-0342 x111 Voice; 843-412-2692 Cell; 843-329-0343 FAX
 
I agree with you and your answer.

I work with both a lot and I can pretty much do anything in either DeltaV or Controllogix... I have yet to run across anything unable to do yet and we have some fairly complex stuff.

P.S. I used to think DV was the ticket... now I am a larger ControlLogix fan. And as I have said over and over on this list... "It is not the paint set but the painter."

Dave
 
J

James Ingraham

Gazsi: "Really you mean Rockwell is the best solution you have been exposed to."

Absolutely. I would LOVE for someone to come along and show me a better system.

Gazsi: "There are manufacturers out there that are light years ahead..."

That one I'm going to disagree with. While there may in fact be someone out there I haven't run into, there certainly aren't any MAJOR players that "light years" ahead.

Gazsi: "...with vastly superior real time Ethernet solutions."

No Rockwell platfrom currently support any flavor of real-time Ethernet. However, this isn't really an issue for me. I've got quite a bit of discrete I/O and many variable speed drives running on EtherNet/IP with no problems. No, I wouldn't be able to do co-ordinated motion at 100 micro-second updates. Fortunately I don't need to for my applications.

Also, note that I said that Logix is the best "solution" I have found. I'm including hardware, software, and communications. I'm including controller, HMI, drives, I/O, and, yes, motion control. Importantly, I'm also including marketing.

-James Ingraham
Sage Automation, Inc.
 
D
I think this is a dead wrong answer. It is not the system but what you do with it.

I have DeltaV systems and Controllogix PLC systems and you cannot tell them apart (intentionally). We designed the same look and feel into each. And yes we are doing some "trick" "DCS" stuff in that old PLC. :)

This reply shows ignorance on the part of the poster. An "old iron" view of PLCs. Get out there and find out that your cheese has moved and the two worlds have merged in the middle now.

After all the DeltaV is just an Intellution HMI on top of a controller... been there and familiar with both.

Dave
 
Ken you made the statement “There is no comparison between a PLC & DeltaV”, with which I agree 100%. I have been involved with several implementations that engaged some of the country’s “premier” programmers. I have never been more under-awed as I was with DeltaV
 
B
I am generally underawed by the capabilities of any of the DCS systems I have played with yet they do have some features that are worth having, that a typical PLC/SCADA package does not implement very well. One of these things is enforcing uniformity in the way functions are handled. Alarm handling is much improved in the latest versions of SCADA packages I have worked with (like WW and RSView32) but they still have some way to go.

I do think the SCADA packages run rings around your typical DCS for data logging and access to the logged data.
 
B
I keep hearing that kind of thing too. Snap I/O was presented that way to me by a number of people. Yet a customer of ours with thousands of Opto22 NODES in use, recently asked us to add some means of remotely resetting the ethernet adapters because they have had several that went off into never never land and refused to respond to the host.
 
As a purchaser, user and teacher in this field I can say with some authority that the cost of Rockwell software is prohibitive. Our university will allow its AB products to live out their useful life while we replace them with other brands (mostly Omron and Siemens).

The bottom line is simply the bottom line.

AB may be better but it is not 5 to 10 times better as the cost would suggest.
 
Mike,

I didn't realize Topdoc was still avaliable, it's DOS-based, right? I used it back in college when I was first learning PLC programming, it was easy to use and understand, but now all I use is AB.

Thanks for the info.

Mike
 
Although the cost of programming and configuration software is prohibitive, I actually do not mind paying for both the hardware and the software. Where I take issue is with (especially AB although I am sure others are the same) the cost of technical support. When I have already paid an arm and a leg for software and hardware that supposedly works and for accompanying manuals that supposedly tell me how to put things together, I am expected to open my wallet again for technical support. Why is it that the equipment and software do not always work the way it is implied in the manuals? Other vendors, for automation equipment and other types have indicated that I get free support forever.
 
P

Phil Corso, PE

Stephen, here's an even simpler answer... because of our litigious society it's best to "do business" with corporations having very deep pockets!

Just search the web for recent lawsuit settlements!

Phil Corso
 
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