PLC Ladder Diagram to Arduino Sketch Conversion

• Nov 30, 2017

• Thread starter
• #2

Helepolis

Mechanical

Dec 13, 2015

212

IL

Thanks for the help!

I found that post already (prior to posting here).
I asked the question for the same reason you mentioned yourself, there isn't much info and what is out there, is a mess and nothing concrete.
So i thought that I'm missing something.

Anyway, thank you again!

 

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• Dec 7, 2017

• #3

mudandsnow

Electrical

Nov 12, 2015

77

CA

Just a random guess, if you are having timing problems it could be that you are using interrupts and putting too much code in them.
I made that mistake on a similar project. Try to do as little as possible in the interrupts, just increment or toggle a variable and then check the variable in your main loop to see if the interrupt was triggered.

 

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• Dec 11, 2017

• Thread starter
• #4

Helepolis

Mechanical

Dec 13, 2015

212

IL

mudandsnow said:

Just a random guess, if you are having timing problems it could be that you are using interrupts and putting too much code in them.
I made that mistake on a similar project. Try to do as little as possible in the interrupts, just increment or toggle a variable and then check the variable in your main loop to see if the interrupt was triggered.

Click to expand...

Thanks, sounds very reasonable. But the thing is that I'm not using the interrupts just yet.
Tried to make the actuator move between two positions (initial and final) to simulate a simplified version of the ventilation sequence that we need from our machine, so there isn't much going on in the code.
But the most peculiar thing happens when i run the code, if i leave the code to run just the initialization of the actuator and the commands to move to position 1 (initial) everything seems to work fine.
But when i add the second part, that moved the actuator to position 2 (final), which is basically a copy-paste when the only difference is a single input pin change that corresponds with the position 2 the whole thing stops from working.
After playing with the code Iv'e noticed that if i add the "delay" function it helps, but it adds up to more than 8 seconds of delay time, that makes the operation very inefficient.
I just cant understand why adding the same piece of code that initiates only after the first part was compiled completely ruins the WHOLE thing.

 

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• Dec 11, 2017

• #5

mudandsnow

Electrical

Nov 12, 2015

77

CA

That does sound strange. Could be a copy-paste error, maybe you missed one of the changes you should make to the copy. That's where I usually screw up my copy-pasting. You could try locating the problem by commenting out portions of the position 2 code until the position 1 code starts working. If you post your code I'll see if I can find anything.

I am curious what you mean by 'ventilation'? Is this a building vent or a human lung emulator or something else?

 

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• Dec 13, 2017

• Thread starter
• #6

Helepolis

Mechanical

Dec 13, 2015

212

IL

mudandsnow said:

I am curious what you mean by 'ventilation'? Is this a building vent or a human lung emulator or something else?

Click to expand...

It's part of an MVP prototype for a therapeutic machine for lung treatment.

About the code, it's crazy simple, about 15 lines for each direction. But i had it rewritten so many times that it stopped working all together.
I'll get it back to working order (with the cumulative delay) and post it, because I'm at a loss.

 

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• Dec 13, 2017

• #7

mudandsnow

Electrical

Nov 12, 2015

77

CA

It's hard to bother with version tracking for such short code but I recommend saving a copy of your code every time you have a successful test. I found having an 'InProgress' folder and a 'Working' folder makes it a lot easier to revert to working code.

Funny coincidence, my linear actuator that used Arduino was for lung stuff too. Not treatment though, just simulation. VacuMed makes a much nicer one than I made. I'm guessing you need something different but this could give you some ideas.

http://www.vacumed.com/zcom/product/Product.do?compid=27&prodid=294

 

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• Dec 13, 2017

• Thread starter
• #8

Helepolis

Mechanical

Dec 13, 2015

212

IL

Thanks for the advice and the link!
It was my first suggestion as a possible solution, to use a rotating link with a connecting rod, this will give a perfect sinusoidal air flow but for some reason it was rejected.
Instead the linear actuator was opted as a solution, I'm guessing that the fact that this an MVP prototype and the link-rod solution requires much more calculations to control the flow withing the set parameters.

 

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• Dec 13, 2017

• #9

mudandsnow

Electrical

Nov 12, 2015

77

CA

That rotating link seems so much simpler and safer than making a linear actuator change speed throughout its stroke and turn around at adjustable end points. The one thing I liked about the linear actuator is it allowed us to try non-sinusoidal breath patterns but in the end that wasn't really needed and it could have been done with a rotating link.

 

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