# Can I replace PLC with an Arduino?

Joined Dec 11, 2013
53
hi,
i need to do a small automation. it is an industrial one. i need the feasibility of using arduino there.

#### djsfantasi

Joined Apr 11, 2010
6,200
In general, yes!

In reality, it depends.

Are the featured system requirements available on both processors?

How are your coding skills? You'll have to do some translation fd.

It Is doable.

#### takao21203

Joined Apr 28, 2012
3,696
Yes exchangeable but you have to reprogram when hardware facilities are used.

Also you have to look at memory organisation.

Basically you can convert most sketches to PIC C source relatively easily.

And you need to consider the relative computation capabilities of the Atmel and Microchip IC in question.

#### bertus

Joined Apr 5, 2008
20,336
Hello,

Many PLC's use signal levels of 24 Volts.
The arduino or other microcontrollers will not accept those levels.
You will need to convert the levels to the ones accepted by the arduino or other microcontroller.

Bertus

#### ErnieM

Joined Apr 24, 2011
8,021
What type of certifications are necessary in your industry? What opperator safety standards or reliability standards must you meet? Anything for intrinsic safety standards? Flammability? Arc fault?

Your answer better be no standards whatsoever because the Arduino will meet none of them unless you do your own certification analysis and testing.

#### strantor

Joined Oct 3, 2010
5,225
Generally a bad idea for the reasons ErnieM stated and also because it isn't serviceable/configurable by anyone except by the person who programmed it (you). People responsible for manufacturing plants staying productive generally prefer PLCs because they need machines that can be troubleshot or modified by anyone on the maintenance team, not just "that one guy who used to work here 10 years ago" or "that contractor who told us he would save us a lot of money but now we can't reach him."

#### mcgyvr

Joined Oct 15, 2009
5,394
Is an arduino capable of being used where a PLC might normally be used?... Yes it might..
Will it be plug and play with existing sensors/motors,etc... no it more than likely won't..
Will it meet the same standards,etc.. heck no..

FWIW.. I use Arduinos at my work all the time for "industrial automation tasks",etc.. but this is for in house machines only used at my company and not products we sell to others..

#### tcmtech

Joined Nov 4, 2013
2,868

#### strantor

Joined Oct 3, 2010
5,225
For medium duty industrial control and one off stuff these are hard to beat! They became my goto device for basic to medium level logic control that has to handle rough service conditions.

http://www.bb-elec.com/Products/Controllers-HMIs/Controllers/TECO-SG2-V3-Programmable-Logic-Relays.aspx
I clicked the "software" link to find out how much the software costs, and it just downloaded a .zip file. WTF? Free software and you don't even have to register to download it? That's unheard of.

EDIT: just for S&G I went ahead and installed it. Kinda clunky, but you get what you pay for. Seems like it would do the trick though. I might try this next time I need a brick PLC.

Joined Jul 18, 2013
20,087
The PLC already has the I/O conditioned all in one solution, with using a μP you have to provide this in the way of relays or Opto22 interface boards are a nice way to go to achieve this.
The draw back with the μP is that you have to set up a Status Ram to store the updated logic every scan, the same way a PLC does it.
The Smart Relays mentioned are made by several manufacturers, many just relabeled.
Max.

Joined Dec 11, 2013
53
In general, yes!

In reality, it depends.

Are the featured system requirements available on both processors?

How are your coding stills? You'll have to do some translation fd.

It Is doable.
I have experiances with pic avr and arduino. I wish i can develop a one . What about its consistancy?

#### tcmtech

Joined Nov 4, 2013
2,868
I clicked the "software" link to find out how much the software costs, and it just downloaded a .zip file. WTF? Free software and you don't even have to register to download it? That's unheard of.

EDIT: just for S&G I went ahead and installed it. Kinda clunky, but you get what you pay for. Seems like it would do the trick though. I might try this next time I need a brick PLC.
There is a V3.51 software on the web someplace which is a bit better to work with (reverse programing compatible with units back to V1.6) but for free and for people like me that learned PLC on the old ladder logic stuff from the 80's and 90's it and these units for the price are not bad at all.

I have several now that have been in seasonal to near continuous use for nearing 10 years functioning as smart multi fuel boiler controllers that have yet to ever give me issues.

#### BR-549

Joined Sep 22, 2013
4,938
Have you got $69. There will be no consistency with the arduino. #### MaxHeadRoom Joined Jul 18, 2013 20,087 If you want a challenge and go cheap, you can still pick up the old Motorola MC14500, one bit PLC chip for simple boolean ladders style function, I used one when they first came out and built a simple PLC with it. Depends on the complexity of your project. Max. #### David Meed Joined Apr 8, 2011 7 hi, i need to do a small automation. it is an industrial one. i need the feasibility of using arduino there. Yes, but... We had a plc Heating/Ventilation control taken out by lightning at the non-profit where I work about 4-5 years ago. To replace it was probably$600-800-1200 for the electronics and $2-3000 for the software to program it. I did get an Arduino to work and figured out the electronics on a prototype shield to connect to all the sensors and controllers - but I have an electronics background for the last 30 years. And my job is a salaried position, so my time wasn't considered in the expense column (figure at least a couple of weeks). It's working - sorta - the room is staying to temperature, but I haven't got the final details on the real time clock to turn it on and off automagically programmed yet. (Real Soon Now...) The electronics probably cost us around$500 or so - but that is buying three or four of everything so we have replacements down the road - I don't expect to be able to buy the same hardware in 10-15 years when these boxes die.

I didn't think about it until I got into it, but arduinos are NOT hardened and in an industrial/real life situation will likely take hits that will fry them. (people poking around, static discharge, lightning, electrically and magnetically induced currents and surges in sensor wires, etc. etc.). I took a lot of notes at the rugged circuits page https://www.rugged-circuits.com/ruggeduino/ and implemented a number of their protection schemes in my circuitry. Would highly recommend reading and understanding what they are saying if you proceed with an Arduino.

Bottom line, if your time is free and you can get a hardened board - it might work. Are you going to be able to dedicate the time to create a finished/polished solution. Do you have the  to rebuild/replace the electronics two or three times when the first iterations die because of (?something random that wasn't in the original spec?)?

Not trying to discourage you, just making sure you know what you are jumping into.

David

#### Walla_Walla

Joined Jan 13, 2011
1
I have a six to eight Unos with TFT screens operating in a production environment
for over a year but they're configured as throw away items should they fail.

Been toying with the linked Arduino based PLC. Lots of capabilities but we have
little long term experience (yet).
https://www.digital-loggers.com/plc.html

#### neuhauser

Joined Mar 3, 2017
6
Just giving my 2 cents:
I've been programming PLC's for 20+ years with an electronics background and just started working with Arduinos. I've also looked at using an Arduino to replace a PLC. The question is "Is it really worth it" given the low cost of some of the smaller bricks as the 'CLICK'. I've programmed $10K Controllogix and PLC 5/80s along with SLC's, MicroLogixs and the 205 series from AutomationDirect. A couple of years ago I set up 2 AutomationDirect VFD's (one slaved as a follower with encoder feedback) controlled by a Click using RS485. I was surprised with the capabilities the little processor had- Double Ints, Reals, subroutines, etc. for under$100 with free "decent" software.

Bottom line- it isn't worth it unless it's for yourself for kicks and giggles. The PLC has internal error checking, optimized house-keeping (I/O updating, comm updating, etc.), and built-in tested and proven functions.
Also if it's for anything automated involving people DON'T DO IT! Unless you can include processor, program, and I/O update error checking.

Me- I'll probably set one up just for the hell of it.

Joined Dec 11, 2013
53
thank you all...........

#### lynf

Joined Jan 11, 2018
2
You can try out for free a fully functional Arduino based PLC that is and self-contained with own command set, editor and a unique bit-stack architecture, suitable for modern microcontrollers like the Atmel AVRs, PIC devices, etc. Check out the uTile Demo Project on this github repository:

https://github.com/lynf/Arduino-PLC

Get the executable file m328-demo-utile_v01.hex from the git repository link, flash it to your Arduino UNO or Nano controller board, and start using this modern PLC. Ideal for students, teachers, experimenters and those interested in automation projects. The repository has comprehensive documentation and manuals for setting up and running the uTile PLC.

Please note the uTile PLC is not intended for industrial applications and is not for use in any safety-critical or high reliability applications. For such applications, a commercial/industrial type PLC is recommended.