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nchinoy
05-26-2005, 12:27 PM
This is one topic i really am wanting to discuss.. I have seen a lot of places where people prefer to use PLC's in the industry, even when the complexity of the job is low enough and it would be a relatively simple walk in the park types implementation for a mC based board... Not to mention the oodles of cash you would be saving on them....

So why are PLC's more popular over Micro's in the industry ?

Maybe from maintainence point of view ? but most plc's require their software which also costs a bomb... to program them..

Umm cant think of too many of the head right now ...

Reasons you people can think of ?

Nimesh

anuplonkar
06-14-2005, 02:06 AM
I think the answer lies in their origin. PLC's were replacements/successors of the original SEQUENTIAL relay logic. These were easy to program and did not require any complex knowledge of low level programming.
micro's maybe good enough for a small to medium sized industry but when it comes to huge industrial applications, developing customised solutions using micros might not be a good idea since modularized equipment in the form of plc controllers. i/o modules and easier sw programming is already available.
In such a scenario using micro's might be the same case as reinventing the wheel.
regards.

nchinoy
06-14-2005, 09:59 AM
Umm interestingly i met some people who were programming PLC's for a living .... He told me the last project he was working on was using a SEIMENS PLC... with 800 i/o's ....

Now i wonder what would my little micro do there ;-) hehe ...

Anyways as far as the project is small - mid sized i still think micro is the way to go... For 800 i/o by all means use the PLC my friend...

nabe
06-15-2005, 12:05 AM
8)

ya ur correct...


any body can make a compiller user friendly that can handle ladder logic and stl logic
as well as very user friendly logic d trasfer d program 2 the micro on d fly.
may be u use a bootloader

Althouth im working on it. :D some sort of improvements already done


yes they can't handle many I/O;;

but they r very useful 4 low cost applications

nchinoy
06-15-2005, 10:55 AM
Hey Nabe ... what are you using to make your project ??? ;-) sounds interesting .. if you want ... make it open source ... that way others can contribute to it too ... :-)

Let me know any ways what have you implemented and how ... just the jist of it ... got some ideas too ... am gonna be working on making the hardware for a generic I/O micro based board... Then need to work on the software part..

nabe
06-15-2005, 11:05 PM
hey
:D

ok
i had make a board containing I/p and O/P module as in PLC. then a pc micro interface which program the micro.
The pc soft convert user language to micro controller logic and upload it to micro flash memory.
now the user logic allowed like

IF SW1 IS ON
AND S2 IS OFF
OR REGULATOR > 45
THEN MOTOR IS ON


now i am working on a boot loader ;ladder logic and stl logic to microcontroller(here it externally may be called as plc machine language) hex converter on PC.

i think u got d idea. :idea:

with love. 8)