Any recommendations for data loggers?

ratio

Specifically, temp & RH. I need roughly a weeks' worth of data, every minute. Bonus would be a days' worth every second. An even bigger bonus would be wireless, to either a phone or a receiver of some kind that supports at least three simultaneous loggers.

I've got a few of the E-bay specials, and they mostly work, but I think it's about time to get a real instrument.

Zman

Check out these guys http://www.onsetcomp.com/products/data-loggers-sensors/temperature

I have not used there wireless stuff but the USB ones work great. I have 2-temp/humid and one thermocouple.

They are perfect when one person complains about the heat and another about the cold in the same room at the same time. The t-couple is great for radiant systems as you can read the temp of 4 pipes at the same time.

I am going to meet an elevator guy today who insists the equip room temp control is working fine. I can't wait to show him the graph where it spikes over 90 degrees a few times a week. Kind of takes the "subjective" part of the conversation away.

JeffM

I'll second what Zman says - look at what Onset offers. I have used their stuff for years, and it's easy to use, reliable, and cheap as loggers go. If you don't need the flexibility of remote sensors, they make ones that are just what you need - temp and RH in one box. Haven't used their wireless stuff yet. Give them a call and they can point you to the best model; their tech help is great.

ratio

Thanks guys, I'll check them out.

Sailah

I have a fairly complicated setup but one that works well. I'm using it to accurately measure steam trap temperatures.

The hub of it all is a Raspberry Pi mini computer. It then outputs the temp readings from 3 digital thermocouples to a website where I can remotely monitor it.

I have one of the Onset data loggers I bought as a first try with data logging and I was not impressed.

Since what I am monitoring is quite a walk, it was so much nicer to hook the Pi up to my wifi network at work and then view the results there. I can easily pull up the results on my smartphone anywhere.

I can send you more details if you like, don't know how complex you are looking to get.

BobC

Peter,

i tried a 4 channel DS18B20 based temperature logger last year, It worked - kind of. By the time I got the buggy software to work and massaged the data into a format for a spreadsheet it would have been easier to just manually log the data myself.

I'd be interested in what the setup your using is like.

Bob

ratio

My intent is to drop one in the return, one in the supply & one sitting on the stat, & pick them up after a week. I've had to chase difficult humidity issues enough times now that spot checking with a psychrometer just isn't cutting it any more. The ability to pull live/near live data when I'm on-site is a big plus too.

I've thought about rolling my own from time to time, & of course that would get me the exact thing I want, but I have too many projects going on right now so I just want to make the company buy something that I think will work.

Thanks for the suggestions!

Sailah

BobC said:

Peter,

i tried a 4 channel DS18B20 based temperature logger last year, It worked - kind of. By the time I got the buggy software to work and massaged the data into a format for a spreadsheet it would have been easier to just manually log the data myself.

I'd be interested in what the setup your using is like.

Bob

Mine also uses the DS18B20 probes. They feed into a bread board and then it's a matter of hooking up the Pi.

I have to admit I cheated and hired someone to program the Pi. No way I could have done that. He set up the temp logging and also integrated a steam solenoid that the Pi also controls using random timing to simulate thermostatic control.

The end result is output into SQL which he then ports to the website. How any of that happens I have no idea.

But here's what it looks like, this was a simple monitoring of inlet temps on a radiator I have running tests on. It's measuring in C and you can see the boiler shut down early afternoon. Mine also records events like certain temp thresholds etc because I'm doing more than just looking at temps.



I'm laying in bed watching Jason Bourne and can see what's going on with temps on my radiator at work 20 miles away lol.

It does have limitations though. My temp probes are about 3' and need to attach to the breadboard. No idea if they could be longer with wiring since they output a digital signal. Mine has 4 inputs but I think I could do 8 since I have a 8 channel DAC.

If someone really wanted to duplicate this setup I could have my developer strip out my website and details. Then I could send you the disk image to flash the PI. It does take a bit of computer geekiness to run but it works awesome and is very accurate. Mine logs for 8 days then records over. Also can download a CSV file for excel queries.

Bob you could drive over and I could show you in person?

Sailah

Here's the breadboard and Pi in the black case. This is overly complicated because I'm running a LED as a failure, buzzer failure and also conductivity probes which all add wires.

The DAC is the small back rectangle in the middle. All the wires do is allow you to connect to the tiny pins on circuits. It's slightly relaxing to hook it all up I find. Of course my developer made a nice diagram and all I had to do was follow it.



Now that I look at the diagram I might have been wrong about the DAC. Looks like it's not needed for the temp probes but I was using it for my conductivity measurements. The temps just need a resistor.

BobC

Peter, my days of driving over are long gone but thank you for the offer.

You can extend the wiring on those probes because there is so little current involved, try to dress the wires away from any power lines that might have noise on them and you should be fine.

My probes have a "headphone" plug on them and I can tell you just using a headphone extender resulted in intermittent operation. I suspect the jacks on the extension cables are intermittent, better to solder everything to insure signal integrity.

My ability to code is pretty dismal, hell I'm an old analog guy who thinks digital is the work of the devil.

Bob

Sailah

Oh and mine you can set up the intervals at whatever you like. 10/sec, 1/sec, 1/ min it just stores it in a huge excel file. I think recording for a week straight, 2 samples/sec the file was 50mb.

My Pi was hooked into the wifi at work and I could remote in and change anything just like I was in front of it.

Jamie Hall

If you're not really keen on things like computers... I've had very good luck with a brand called "Hobo" loggers (http://www.onsetcomp.com/). They come in a variety of sensors. The software that goes with them (get the Pro version -- more expensive, but much easier to use) does all the hard work of setting them up and reading them and all that. They aren't cheap. They are bulletproof...