Can I replace PLC with an Arduino?

dendad

Joined Feb 20, 2016
4,450
There is nothing really magic about PLCs. You could well make a PLC with an Arduino if you wanted to. But as many have said, is it worth it?
I design and make industrial control equipment and they are not PLCs but dedicated devices. One thing to make sure in your design is to do your best to have bullet proof power supply and I/O interfaces.
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
The Arduino does not have this but that is not a problem as such. The PLC brain at CPU level does not either. The interface to the real world is a design feature. Most of my boards run on 24V as that is one of the main standards of industrial control equipment. It does not matter what controller you use, just build accordingly, like opto isolate as you can and put lots of bypassing and transient protection in. For industrial control, overkill is good. the environment can he pretty harsh. Use high temperature components. That is one thing an off the shelf Arduino will lack.
If you go the way of Arduino, make sure you document it well as to allow someone else to take over if needed.

Do you want the device to run PLC ladder logic or just have a custom controller to do a job? Custom is ok. None of the devices I've been involved in has come anywhere near ladder logic. And there are vary many different installations running, from controlling a portable sawmill, wrapping candy bars, running irrigation systems, motor control....
One of my irrigation monitors is an Arduino Mini Pro as the complete little board is cheaper to buy than the parts to make it.
In fact as I type this, I just got a text from one of them to tell me it is still running :)
So after that long waffle, an Arduino can quite well work for you, but the down side will be it is custom so maintaining it in the future could be a problem. And you will have to design the electronic interface and power supply as well as the programming. There could be legal problems with certifications in some places if that is needed. But if it is for your own use, have a go.
 

lynf

Joined Jan 11, 2018
2
For small systems you could also look at the SmartRelay which is the little brother of the PLC.
Comes with timers and real time clock etc.
Max.
I'm in agreement with the previous comments on issues involved with using an Arduino as a PLC for small automation projects in commercial/industrial settings. If the application requirements include the need to address electrical certification, reliability, safety, emc qualification, environmental qualification, compatibility with commercial PLC equipment, program modification and maintainability, etc., then the Arduino platform falls short of meeting such requirements. You'd be much better off looking at commercial equipment in this case.

Arduino controller boards are designed as low-cost platforms for students, designers, experimenters and the curious, be they neophytes or experts. I think the reason behind the often asked question "Can I use and Arduino as a PLC?" is people can imagine a useful low-cost PLC type solution running on an Arduino and would like to know if this is possible. The short answer is "Yes, it is possible."

The uTile PLC started out on an Intel 8051 microprocessor and was later ported to run on an Atmel ATmega328P device. uTile can actually run on a ATmega328P chip alone, so it is approaching "Embedded PLC" status.

The purpose of the free uTile Demo project is to allow interested users to try out for themselves a fully functional PLC on their Arduino Nano or UNO controller board. The uTile Demo is especially useful in cost sensitive applications. The goal of the uTile Demo project is to encourage the use of PLC technology in a wider range of cost-sensitive applications.
 

MaxHeadRoom

Joined Jul 18, 2013
28,576
The Opto22 boards and modules are useful for providing industrialized I/O for any DIY PLC, one of the biggest advantages, and also the main reason for a Industrial version is the ability to display all logic in ladder format for shop floor trouble shooting.
Max.
 
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