Re: PLC's and industrial automation

Gah! I looked over those pages...

The chips you mentioned seem to come as actual chips, or just on PC
boards. Obviously they'd have to be assembled.

The programers would have to be housed, and then I'd need to learn
how to program them. (seems complicated).

With PLC's, they come in nice boxes - just bolt to your chassis, and
plug em in.

Programming PLC's is a no brainer. Any idiot can do it (I learned
PLC's in my high-school electronics class - trust me, any idiot can
do it).

If my time was worth, say, $75/hour, which would be more economical
for CNC applications?

For more advanced stuff, micro-controllers are the best choice, but
for simple automation the PLC's are nice and simple.

Regards,

Robin

--- In CAD_CAM_EDM_DRO@y..., Doug Fortune <pentam@h...> wrote:
>
> OK, no-one has said just what the darn things are! Just a quick
overview
> please. Is it just a little loop logic and input/output relays?
>
> I'll give you a counter-example: A Scenix (now Ubicom) SX-28
> programmable microcontroller chip:
>
> http://www.ubicom.com/hardware/sx28ac.html
>
> programmers available (~$200 range) from:
> http://www.parallaxinc.com/html_files/sxtech/sxtech_home.htm
>
> It gives you 20 I/O (dedicated or multiplexed), analog in & out,
> and 50 or 75 MIPs (millions of instructions/sec). If you prefer
> not to use assembly, there are C compilers (at least one is free).
> I have one very complex program that is 35 pages long, and am
> still only using half the ROM! The chip is only $5.
>
>
> The SX-52 runs at 100 MIPs and has 40 I/O pins, and twice the
> ROM storage. This chip is around $10.
>
> - - - -
>
> I am assuming the PLC's have no where near this sophistication,
> so unless someone tells me otherwise, I am still going to assume
> PLC's are 1970's technology, and it is more worthwhile to spend
> time learning something new ( like high performance
microcontrollers)
> vs something old (like PLC's). The only two advantages to PLC's is
> perhaps that they are field programmable & integrated with high
current
> drivers - but really that is no different than putting some relays
and
> programming pins on a little SX circuitboard.
>
> ...unless I'm way off base, of course.
>
> Doug Fortune
> http://www.cncKITS.com