Concept Programming Software IEC 1131

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Thread Starter

Charlie Pritt

I am wondering what everyone thinks about the new Concept IEC 1131 programming package. I am wondering about the change over process, from conventional ladder to the new standard. I
understand that with Concept, if you don't have the latest release of the PLC program you can not connect to the processor. I can see where that could be a problem. I also heard that not all processors are compatible with the software, does this mean you will either upgrade your PLC or have two different programming packages around the plant? I just want to hear some other views on the standard, both good and bad, and not only for the Concept package.

Thanks,
Charlie
 
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Bill Szuminski

Well your almost right Charlie...
Concept does allow you to connect to a PLC. If you want to upload the program from the PLC to your PC you do need the "original" compiled program to become "equal" to the PLC's program. If you are only doing the 984 ladder you do not need to have the original program. All Quantum processors are compatible with Concept 2.2, some older Compact 984 are not but the "TSX" versions are. All of the current released Momentum PLC's will be able to utilize ladder and all except one are IEC compatible. All the newer released PLC's from SqD (Modicon) are designed to work with
Concept, unlike some manufacturers that force you to have 3 or more packages. If you are only going to use ladder, you could buy ProworxNXT from SqD and have access to every PLC currently
available from Modicon... 984, Micro, Compact, Quantum and Momentum. WGS
 
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Sage, Pete (IndSys, GEFanuc, Albany)

Let me start this by saying I don't know anything about concept. I do know a little about IEC 1131. I know there are IEC 1131 specific
programming constructs that work differently than a lot of standard ladder enviroments. Hence they have probably redone the PLC firmware execution engine to support IEC 1131 and as a result they
don't support the old execution model with the new firmware (probably do to limited static ram/rom space on the PLC)

Pete
 
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Ranjan Acharya

As far as not being able to connect to a PLC if you do not have the latest version of the programme on your hard drive, we have been living for that for years with the Siemens/TI tool APT (an interesting precursor to the IEC 1131.3 age).

With any IEC-1131.3-based tool, having the latest programme is a must, and will, in fact lead you to a better structured and more tightly controlled
modification and update scheme to that Dick and Harry will stop piddling with the system and leave it to Tom who actually knows what he is doing.

However, I heard through the grapevine that Siemens (at least) is thinking of PLCs with oodles of FlashRAM that will allow engineers and technicians to download the complete programme with structure and comments. It will be
interesting to see this once it enters the market place.

RJ
 
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Alastair Fordyce

We have two individual comments from two Systems Engineers as a reply to the e-mail.

Comment 1:
I can't speak expressly about the Concept software as I have only worked with an evaluation copy but I have considerable experience with IEC1131 programming on European sourced PLC's. I also keep up to date with ladder programming on US (conventional ladder) PLC's and a few others totalling seven different PLC/software packages.

Ladder programming is only "conventional" for those with an experience in PLC's that were developed as relay replacements and continued with that thought process (have you ever tried to add two numbers together with relays?). While IEC1131 includes ladder programming as a language option, the whole approach of 1131 is more of a top down one strongly influenced by software programming concepts. A programmer in IEC1131 tends to produce more modular code rather than spaghetti type code since programming tends to be
easier this way (note this is a generalisation and a good programmer is a good programmer whatever the language).

With regard to processors, there has also been a change in approach from using interpreted code to using compiled code. The advantage of the latter
is the ease of upgrading operating system versions (software rather than hardware) but the disadvantage (if any) is the need to be very careful with the source code. The compiled code will typically contain date and time stamp for the source code files so, not only do you have to maintain copy of the source code in a safe place, you also have to leave the source code untouched by the editor so that on line program changes may be carried out. This is a good way of developing a healthy attitude to version control.

A review of the improved memory utilisation and the power of user defined function blocks under IEC1131 certainly outweighs the minor disadvantages of the source code "housekeeping".

As to having more than one PLC software package on a plant, you tend to end up with this anyway as new PLC's are released and the old ones fall out the bottom of the support basket. You tend to keep legacy software packages for legacy PLC's (who still keeps a P190 & tapes for Modicon 484's?) as the costs of replacing a reliable operating PLC system aren't usually justified
in the eyes of the company accountant.


Best regards,

Alastair Fordyce TM.IPENZ,REA, NZCE,CQA
Systems Engineer
Bremca Industries Limited www.bremca.co.nz
PO Box 7169
Christchurch
NEW ZEALAND
tel +64 (3) 332 6370
fax +64 (3) 332 6377
e-mail [email protected]

Comment 2:
IMHO that while ladder programming is easy to debug on site when everyone is screaming at you to get the plant running and your hair is beginning to part company with your scalp - it doesn't lend itself to development with the same elegance that the structured text languages do.

The absolute beauty of any IEC1131 language is the ease with which your can re-use code.

Good example would a project where we had 37 identical processes running in 3 PLC5's, putting this into a ladder based programming language was time consuming and prone to error. At that time the 6200 software didn't cater for user defined functions simply. (Yes I know it could be done - but the code would have been hideous and we would have been shifting bits left, right and centre). Whereas the same project in an IEC1131 language would require writing a user defined function and defining 37 times. One bit of code to check for typos.

More generally, if you can program it doesn't matter (beyond the cost of continuously upgrading and re-licensing) how many different flavours of PLC you have on a site. Programming is as much about understanding the process and reducing it to succinct logical blocks as it is about keystrokes. Knowing which keystrokes to use is usually addressed with a quick look at the manual. And if you write code that uses the specific nuances of a particular PLC language then you should be marched off site. Chances are
nobody else will easily understand even if they are familiar with the language and PLC.

In fact I would suggest that using many different flavours of PLC and language will make YOU a better software engineer. You will focus on
writing the code in as generic method as possible and less on the glories of a particular PLC. The more generic the code - the more maintainable - the better the solution.

The days when integrating different systems was an impossible nightmare and series of compromises are gone and why not look at each PLC on the basis of its suitability for the job, rather than blindly sticking to one supplier.

I guess the other thought relates to programming software - once we used to get the PLC software running on the laptop (usually took 2 days) - anybody who mucked it up would be crucified. Now that Mr Gates et al. have through a monopoly provided the world with a standard hardware interface (Windows) software seems to be more tolerant of other applications. Consequently, the
problems of having multiple vendor packages on the laptop has largely vanished.

Best regards

Jonathan Lyall BE, BSc, Reg Engineer
Systems Engineer
Bremca Industries Limited www.bremca.co.nz
PO Box 7169
Christchurch
NEW ZEALAND
tel +64 (3) 332 6370
fax +64 (3) 332 6377
e-mail [email protected]
 
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Pierre Desrochers

As a system integrator I usualy enter a plant to fill a void created by the crazy downsizing of the 90's. The most important aspect of my work (after making the system work... of course) is the transfer of knowledge to the clients technical personal. Archives and archives and comments, etc.

Here, Concept is creating a few problems.

Although I personally think it's the most fantastic software package in the market, it really scares the sh... out of the technicians when I start about the code being equal or not, and the consequences of it.

One must realise that the PLCs where and are still marketed as user-friendly devices wich can be programmed by electricians ... No so.

When I look at Concept and other pakages I can't help but wonder if all Engineers went to school for so long to punch in lines of code ... Lets face it, this is more configurating than programming. Our knowledge should be about the process not the code... The electricians or technicians who will connect with Concept would
most certainly be in a troubleshooting task or doing a small modification...

With the backup creation feature of Concept, one must be a no brainer to destroy its original line of code. Gosh... it did happen to me once...

Alastair Fordyce wrote :

>>A programmer in IEC1131 tends to produce more
modular code rather than spaghetti type code since programming tends to be easier this way (note this is a generalisation and a good
programmer is a good programmer whatever the language).<<

Wrong - To say this is like saying "My wife is a little pregnant" you either have spaghetti or not whatever the language used. Your note points to the opposite of your afirmation on IEC1131... Choose your party.

Most of the spaghetti code we encounter in all languages is usually created during original commissionning when the programmer is reacting to pressures from above ... is fault is that he should restructure the program BEFORE finishing the project ... (time + money...) Writig a bit of spaghetti is not wrong... leaving it there is.

>>This is a good way of developing a healthy attitude to version control.A review of the improved memory utilisation and the power of user defined function blocks under IEC1131 certainly
outweighs the minor disadvantages of the source code "housekeeping".<<

Again "The electricians or technicians who will connect with Concept would most certainly be in a trouble shooting task or doing a small modification... " I tell you they are scared ... and no rational reasonning will make this feeling disappear.

Alastair uses word like "elegance" and "absolute beauty" well we know which package he prefers but I still feel that programming as nothing to do with poetry.

Basically one must COMMENT and COMMENT again (Here
Concept is the great), Archive and Archive again.

We are working on a multiple zone (20+) PID control process with feedforward and feedback. Without Concept I don't know how we
would have acheive this in the time allowed. Function block editing, is Gods gift to us...

We still use Modsoft to configure holder 984 Thermocouple input cards and do a backup of our clients programs every time we visit... still his technician are nervous whenever they connect to the PLC ... only time will soften this feeling.

My 2cents

Pierre Desrochers
System Integrator
Canada
 
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Scott Cornwall

Concept - hate those dialog boxes. Does allow you to avoid the legacy high maintenance languages LL and IL, although the SFC is a bit limited. Concept
is one of the best programming packages from the major PLC vendors, but I hope Modicon do a lot better with whatever supersedes it. In fact the
programming software offerings from the major vendors are pretty disappointing all up if LL and IL do not suit your requirements, the soft PLC type of software coming from the smaller companies has a lot to offer in comparison.
When are the major PLC vendors going to open their hardware up so we can choose this kind of software ?

Scott Cornwall
 
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Anthony Kerstens

Seems as though PLC programming software has always been pretty disappointing, especially when in comparison to the advanced look, feel, and functionality of regular business software.

What burns me more than anything is I still do wholesale descriptor text editing and duplication in a spreadsheet, and then import a CSV file. This in an age when my wordprocessor can paste cells cut from my spreadsheet and provide a means of editing them.

Anthony Kerstens P.Eng.
 
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