Sure, it's done frequently, but typically as a distributed intelligence
scheme, rather than as a centralized controller. There is often great cost
savings in replacing a PLC with a PIC for a dedicated machine controller.
The same can be accomplished, but the two devices will usually use differing
methods. PLC's are made with the idea that a somewhat graphical programming
language (ladder logic) will make programming possible by someone without
knowledge of a lower-level (a relative term here) programming language.
Hence, the same unit can be used in a wide variety of applications.
Designing a PIC centered circuit that any maintenance technician can program
would be quite a task, in fact the result would be a PIC vbased PLC. Take
apart a few PLC's, and you'll find a variety of micros running them. They
consist of microcontrollers designed into multi-application I/O circuitry
with supporting customizable software that a large number of people are
versed in.

We do PIC's to replace PLC's often - as dedicated machine controllers.
The trick is in the way customer and field configuration are handled.
Generally, we start with a known list of variables, and we design
initialization routines with input switching or sensing to pre-configure. At
times keypad entry is used. We have never attempted the level of application
universality provided by a PLC.

Chris

> -----Original Message-----
> From: pic microcontroller discussion list
> [mailto:PICLIST@MITVMA.MIT.EDU]On Behalf Of dtth
> Sent: Tuesday, March 05, 2002 1:34 PM
> To: PICLIST@MITVMA.MIT.EDU
> Subject: [PIC]:PIC vs. PLC
>
>
> Is it advisable to use PIC to do what PLCs do? Has anybody done it
> before?
>
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