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From: "Walter Driedger"
References: <email@example.com> <firstname.lastname@example.org> <email@example.com>
Subject: Re: Avoiding PLCs
X-Newsreader: Microsoft Outlook Express 6.00.2720.3000
Date: Thu, 17 Oct 2002 03:38:23 GMT
NNTP-Posting-Date: Wed, 16 Oct 2002 21:38:23 MDT
Organization: Shaw Residential Internet
Actually there would be nothing wrong with a Siemens PLC, *if* our entire
plant were based on Siemens PLCs. Your problem is to write PLC logic for a
process with which your are familiar but into a PLC with which you are not
familiar. You have to do this over a period of a year and will be doing a
complete functional test at the end.
Our problem is that we have a plant full of different PLCs each of them
controlling a different process. We have not written the code nor do we
expect to spend any time studying it. One night at 3 AM the system goes
peculiar. We have to fix it NOW. In order to do this we have to find
programming manuals, install config software, study the process logic and
find out where the programming port adapter cords are. Remember that each
machine has different config software loaded into different computers. In
fact, the computer that YOUR config program was loaded into was given to the
local high school two years ago and nobody knows where the disks are. When
we find them, they won't load into Windows NT and anyways, nobody can find
the patch cord adaptor. All this time the clock is ticking at $100K per
hour. (No, that's not my overtime. If only they paid me what I am really
By-the-way, I meant custom PCs with C programming when I said specialized.
"Michael Marx" wrote in message
> We are a German based manufacturer of specialized machinery (for paper
> handling & transport, but that does not matter). We have considerable
> experience and a good customer base in Europe. Nearly (i.e. 99,5%) all of
> our machines are equipped with Siemens PLC which is "the European way" to
> it. It is just the normal and standard thing to do. The Software gets more
> and more complicated due to "modern" developments like field bus (i.e.
> "Profibus"), operator panels (make "Siemens") and and and ... The systems
> are very reliable, and very promising. Much more development to expect in
> the near future.
> Now we want to go into the US market.
> When we mention the word "Siemens" we get a "No No - WE DO NOT WANT
> SPECIALIZED HARDWARE AND WE DO NOT
> WANT SPECIALIZED PROGRAMMING". It just has to be AB (it is usually that
> name), plus odd things like DH or ModBus or FF.
> Now, consider the whole thing from another point of view.
> We have many many years of experience - and a good and satisfied customer
> base - with our Siemens machines. When we switch to AB - God knows what
> happen. The very least thing is that our programmers - possibly with a
> AB "starter" course - are not up to the task. Possibly we have to invest
> into specialized software companies. The worst thing that might happen?
> well proven machinery might totally fail, due to missing odds and ends on
> the software side. Will this be good for the customer ?!? I doubt it. And
> there will be nice clauses in the contract about penalties and such things
> It would not be so good for me as the company engineer, either.
> We know that Siemens is for Europe what AB is for US - and we are working
> this (similar as EN vs. IEC as standard?). But it may not be so easy as
> saying WE DO NOT WANT SPECIALIZED HARDWARE AND WE DO NOT WANT SPECIALIZED
> PROGRAMMING. What is "specialized" depends very very much on your point of
> view, doesn't it?
> So you might also say that the US way of insisting on "AB" as "standard"
> is just another way of keeping international / european companies out of
> US market (and I understand that AB does everything to support this
> Michael Marx
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