Tom writes:

> I have looked around, and there is a transformer on the wall outside the
>  office in question, about 10-12 feet from the PC, so I am thinking that is
>  the problem.  Also, one of the cables going to a saw passes even closer on
>  it's way out to the saw.
>
>  I was thinking that placing the PC on the other side of office would place
>  the PC more like 16 feet from the transformer and perhaps that might be
>  enough, or there is another office we can move the PC to that will require
a
>  little more work in terms of cabling.  Would it matter that the cable to
the
>  saw passes like 6 feet away from the transformer?  Also, would it be
>  possible to shield the transformer?  It's attached to the wall about 7 feet
>  up in the air and is about 3 feet high and about 2 feet across (not that
the
>  dimensions probably matter).
>
>  The PC he used to have would just start booting on its own, besides all the
>  times that it froze up and had to be rebooted.  On the PC he is using now,
>  it is more subtle.  One day, the video driver program disappeared out of
the
>  systray and everything on the monitor was very dark.  I restored this
driver
>  off the recovery disks, but I still can't recall ever seeing a PC come up
>  with a very dim display (that can't be improved) and then suddenly adjust
>  when the video driver icon appears. And all sorts of other little things
>  have gone wrong with it, none of which are show stoppers, but it is not
>  improved by doing a reboot, either.

A shop floor environment is a tough place for a computer, not just because of
all of the oil, dirt and grit, but because of the intense electrical and
magnetic transients. The best course of action is to get the computer out
that environment, if at all possible.

In any circumstance, what needs to be done is provide mechanisms of
communication that tolerate the shop floor environment. In the old days, the
most common form of serial communications between a computer and its remote
devices was current loop. That later came to be replaced by RS-422
(differential serial communications). In contrast, you are probably running
only standard RS-232 from your COM ports, which was never designed to operate
in this kind of environment.

Probably the best thing you can do is purchase a ruggedized PC, along with an
accompanying rack mount, so that you create as electrically clean and as
stable an environment as you possibly can -- and then use optoisolators as
Jeff earlier suggested to communicate with your remote devices.

When we used to be more of an engineering organization, we built these kinds
of on-the-shop-floor systems for any number of organizations (NASA, USDA,
Kennecott, etc.), albeit for larger computers. If you do it right, you can
create a truly isolated, stable environment for the computer but still have
it placed directly on the factory floor and control devices throughout the
length of the factory.

Wirt Atmar