From: "Cameron Dorrough"
Subject: Re: Avoiding PLCs
Date: Thu, 17 Oct 2002 16:15:58 +1000
Organization: Customer of Connect.com.au Pty. Ltd.
References: <firstname.lastname@example.org> <email@example.com> <firstname.lastname@example.org> <2jqr9.76172$oq6.18550@sccrnsc01> <email@example.com>
NNTP-Posting-Date: 17 Oct 2002 06:16:05 GMT
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"Don Pearce" wrote in message
> On Thu, 17 Oct 2002 04:26:21 GMT, firstname.lastname@example.org (Mike
> Harding) wrote:
> >On Thu, 17 Oct 2002 13:56:53 +1000, "Cameron Dorrough"
> > wrote:
> >>And that's one of the *best* reasons not to use custom PC's with custom
> >>software right there..
> >>If the PLC ever needs to be upgraded/replaced, simply translate the
> >>ladder logic, PID loops, etc to the new platform. It is very easily
> >>(especially something like Siemens to AB or vice-versa).
> >>Heaven help you if your plant is reliant on custom PC software written
> >>particular (eg. Microsoft) operating system that is no longer supported,
> >>a PC chipset (eg. x86) that you can't buy parts for.. That's just
> >>for trouble. Been ther done that.. remember DOS? ;-)
> >Yep. And we should still be using it for any kind of control
> >system running on a PC. By version 5 and 6 it was/is
> >pretty stable and has all the features we need.
> Remember Dr DOS? Now that was the one to use in my books. I had a PC
> with that on it until very recently.
Guys, the biggest problem with DOS (any flavour) is that you can't even
*buy* it, let alone expect your clients to be able to get support!
Dunno about the rest of you, but a "what do I type in now?" request from an
operator at 2:00am is not what I'm looking for in a control system...