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Topic: Is arduino right for this project? (Read 104 times) previous topic - next topic


I need to monitor several outputs from my HVAC and wonder if ardrino is the best choice.. I really only need a module that would connect direct to my PC and monitor when any of 5 values change.. all are 0 or 5 volts dc... but cannot find a simple module for the PC and from what I read it could easily be done by arduino or maybe the WIFI module but its difficult to save the data on my PC..

For example here is the simple version of what I need to do...
Monitor for 0 or 5 vdc on the HVAC on line and 2nd stage line and store this data in a file like a text file for example..in say the below format...
date-time, 5, 0 // Hvac on  and 2nd stage off
date-time, 5, 5 // Hvac on  and 2nd stage on
date-time, 5, 5 // Hvac on  and 2nd stage on
date-time, 5, 0 // Hvac on  and 2nd stage off
date-time, 0, 0 // Hvac off and 2nd stage off

Basically logging the condition of the HVAC and 2nd stage HVAC 24 lhours a day and put in a text file.

Then i can write a very basic program to when requested to show a report of how much the HVAC ran over and period and how much of the time it ran in 2nd stage....

Programming from the text file log is easy.. but I need a module or device to connect to my serial PC port i suppose to monitor and log the data to a basic text file on my hard drive..

Any ideas on what i might use to build this project would be greatly appreciated.. and with so many members i hope someone can simply say "OH yeah you need of of those widgets I saw just the other day and would be easy to set up...  as i have searched for many hours on google and have not yet found anything..

I can program and can learn the arduino or the wifi here if I need to if anyone has any idea which one would work for me...  does not have to be arduino.. even any thing i can add easily to my PC that would do this.... Thank you...

If any additional info about what i am trying to accomplish would help please let me know..
Even if it has to wifi and dump the data to the internet i can even do that as i have my own web server and am fluent in PHP and could then write a program on my PC to access the file on the web and process the data...

Geek Emeritus

so you need a datalogger. dataloggers need a clock. the low$ not obsessively accurate way is an RTC module. for a few dollars more and a little more coding you can have a GPS disciplined clock.

 if you store data in a date, dime, value, another value, format you can load it into a spreadsheet. that is .CSV, Comma Separated Value, format

I derive the filename for my datalogger in YEARMODA format derived from the time the event is logged. this gives you an 8 digit + .CSV so the file name inherently works with the ancient 8+3 format used on SD cards.

Best practice would be to use an optoisolator so the HVAC circuits feed, but do not directly connect to, your arduino. an isolated input

look in the Project Hub in the COMMUNITY tab above for Datalogger & HVAC to see what has been done.
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Apr 22, 2019, 10:58 pm Last Edit: Apr 22, 2019, 11:00 pm by wildbill
You can do it with an Arduino and an SD shield to save the data to an SD card.

You could then yank the card occasionally and read it with a cheap reader on your PC. Or you could program the Arduino to spray the data out of the serial port on request and write code on your PC to request and capture it. I assume that your PC isn't close to your HVAC.

Since you have a web server and the expertise to use it, you could get a wifi shield and hit a PHP page with GET requests when the state of the HVAC inputs changes and store it on the server in a text file or database. Wifi shields are still inexplicably expensive though, so an ESP8266 is a popular solution to take care of the  wifi connectivity. 

I used to use an Uno with a wifi shield to gather temperature and humidity data which was pushed to a local web server, but when my router was replaced with one using WPA (Which my wifi library couldn't handle), I switched out the Arduino for a Pi instead. A Pi zero W is cheap and has wifi, but you need to know Linux (a bit) and remember that it's 3V3, not five volts.

Edit: Also, to Geek Emeritus' point, a Pi can use NTP, so it knows the time.


Apr 22, 2019, 11:49 pm Last Edit: Apr 23, 2019, 12:02 am by tommytx
Thanks Geek and wildbill i will look at your ideas and try to come up with something... I know this shows my age but it was so simple back in the day of Commodore 64... (pls don't say never heard of that one) but you could simply place a 1 or 0 on a special pin then look into memory at that address and read the value to the computer screen... nowadays the serial ports are so dang complex.. its not easy anymore.. but hopefully i will get something working... so if anyone else has other ideas I am all ears... the two of you have given me food for thought but i have a lot of experimenting to do unless I find a datalogger that show the step by step to set if up... and i really don't mind spending a few bucks on a commercial one on the market if its simple and not too expensive... Thanks again for your inputs.. I appreciate it..
Earlier i had been looking at the adafruit version 13.95.. looks pretty complicated but I can read well and even though it has huge capability it can probably do simple stuff too like I am doing.. plus there will probably be a fourm for help and since commercial maybe even be able to ask for help if needed...

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