In a message dated 12/25/06 9:49:18 A.M. Eastern Standard Time,
tesla@xxxxxxxxxx writes:
Sorry to hear this bad news. I've used about 40 of them over the past
years
and so far, knock on wood, absolutely none of them have failed in any
manner.
It may be a difference of environment. If you're using yours in museum
settings, they may not experience the temperature fluctuations,
vibrations, filth,
moisture, electrical noise, and general abuse that industrial environments
foster.
Curious --- with all your experience Phil, what brand do you recommend?
I've got experience with the old Square-D Symax, the old Cutler-Hammer,
a couple of the OMRONs, several of the Telemecanique's (the older, cheaper
ones were crap), many Allen-Bradleys (Micro 1000, 1200, 1500, 500, modular
5/01's thru 5/05's, modular 550, PLC-5's), a coupla
Motorola 68000's, and even an
ancient Giddings & Lewis.
I'm most comfortable with Allen-Bradley, because IMHO their programming
software is the best. But if you can't afford the programming software and
Tech Support, and you don't have to coordinate with legacy A-B
systems, I'd go
with Siemens.
Siemens micros have all kinds of nice features, like built in PID
control blocks (as has already been mentioned here), simple
communications setup,
face dial (for a manually adjustable analog input), very compact size, and
FREE software and FREE Tech Support. Their programming manuals tend to be
in-depth, even if less intuitive than A-B. Their Logo series is
nice if you really
need to monitor or change programming right on the controller, or have
minimal text readouts for the operator. Their software also allows
you to program
in either ladder logic or function blocks, whichever you prefer.
A-B has been steadily losing ground to Siemens all over the world,
although I'm sure there's many huge legacy users that are going to
stick with A-B.
-Phil LaBudde