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Subject: Re: Avoiding PLCs
X-Newsreader: Microsoft Outlook Express 6.00.2600.0000
Date: Mon, 14 Oct 2002 19:31:07 +0100
NNTP-Posting-Date: Mon, 14 Oct 2002 19:29:01 BST
Organization: ntlworld News Service
"bob peterson" wrote in message
> "JohnS" wrote in message
> > We have run into a problem, hope someone here can make a helpful
> > suggestion! We have a digital control system which is fairly easily
> > using a plc. (Lots of interlock logic, timers, 4/20 mA circuits, 4 line
> > display, etc) Unfortunately every customer then seems to insist that we
> > build using the make of controller already in use by them. In order to
> > this I am looking for modular electronic systems that we can program in
> > whatever so we can avoid using a PLC, but still have the flexibility to
> > I/O etc as required.
> > We could design from the ground up, but there must be suitable systems
> > there, ideally with CE and UL approval!. Any pointers to possibles
> > much appreciated.
> Most plants need something their own people can maintain. Things
> programmed in "C" generally don't meet that requirement. Think of it
> from their perspective. Would you want to be over a barrel to an
> outside vender who wrote a bunch of custom code you can't fix
> yourself? Particularly if its a critical system.
> Its why they want a real PLC, not some kludge together someone came up
> with that is really good at generating field service revenue.
OK. Many thanks for all the responses everyone. It's not just about trying
to generate service calls tho. Don't think we manage to make much money on
that. But apart from the amount of effort that goes into rewriting code and
redesigning systems for each PLC, there is also a question of IP in the
'know how' of how systems work to control one's own equipment. Giving the
code away for the PLC makes it invitingly easy for a customer to get copies
made elsewhere. Anyway thanks again.
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