PLC Design Using MCU - Page 1
Forum section: electronics / projects

author: amar
author_rank: Contributor
timestamp: April 05, 2013, 10:56:21 am
content: Hii am trying to design Industrial Controller using Micro controller.i will program the system In Embedded C.for better performance system should give linear response & will work in noisy, dusty, humidity, vibration environment andplease suggest me how i can achieve all these requirements.thanks

author: buster7
author_rank: Contributor
timestamp: April 05, 2013, 11:25:03 am
content: why not use a plc

author: Psi
author_rank: Super Contributor
timestamp: April 05, 2013, 11:34:24 am
content: lol, best. response. ever.A PLC is fundamentally different to a MCU. Creating a PLC in software on a MCU kinda defeats most of their advantages.The requirements for operation in a dusty, humidity, vibration environment are all to do with physical design.Case seals, conformal coatings, shocking mounting of pcbs etc..

author: buster7
author_rank: Contributor
timestamp: April 05, 2013, 11:49:45 am
content: are yes i see edited your replyjust asking a question why reinvent the the wheel

author: AlfBaz
author_rank: Super Contributor
timestamp: April 05, 2013, 01:08:19 pm
content: Quote from: Psi on April 05, 2013, 11:34:24 amI don't get it. Isn't a plc just an mcu running software that interprets ladder logic? (forgetting for a moment that all i/o,come from external modules)

author: dr.diesel
author_rank: Super Contributor
timestamp: April 05, 2013, 01:14:58 pm
content: Quote from: AlfBaz on April 05, 2013, 01:08:19 pmYes, you are correct Sir.

author: amar
author_rank: Contributor
timestamp: April 05, 2013, 05:12:50 pm
content: PLC is Costly. MCU based design Is cheapPLC is fix Module. in MCU based design u can add/remove the feature as per requirementbut for MCU programming i have only Embedded CMCU can also take place of PLC so why LOL ?

author: darko31
author_rank: Regular Contributor
timestamp: April 05, 2013, 05:44:18 pm
content: In order to adapt microcontroller to work as PLC in industry environment you would have to add opto-isolation for inputs, add relays (and drivers for them) for the outputs, buy/design PSU for it with all the necessary protection. As mentioned, lets not forget the all important casing, and add the connectors, ADCs, DACs bla, bla, bla.Add all that and you would probably pay a lot more for all the necessary components in order to make it than just buying it of the shelf.You can also program PLCs using C if ladder is a problem.PLCs also have expansion modules if you are missing some requirements, and if price is a problem China can come to the rescue, base models of Xinje PLCs start about 90€ (here in Serbia) which is about 120$ US bucks. We use them at school and the quality is reasonable but they do what they are intended to do.Now if you want to design a PLC, that's totally different story, and if that's the case then go for it.

author: amar
author_rank: Contributor
timestamp: April 05, 2013, 05:54:55 pm
content: yeahbut i want a system for industry which can fulfill the requirement of industrial environment.please share any experience of hardware design

author: dr.diesel
author_rank: Super Contributor
timestamp: April 05, 2013, 05:56:10 pm
content: Quote from: amar on April 05, 2013, 05:54:55 pmPLCs are typically directly designed to fit industrial environments.

author: nctnico
author_rank: Super Contributor
timestamp: April 05, 2013, 07:00:34 pm
content: Quote from: amar on April 05, 2013, 05:12:50 pmNot really. An entry level Siemens PLCs costs less than $100. Good luck designing something cheaper which is just as rock solid. Where PLC gets expensive is when you need analog I/O. Digital inputs and outputs are dirt cheap though.