Data logging?

[bruce]

Now let me say first off I have no clue (nor a deep pocket with lots of $$$'s) what I am doing but like all my other projects I am willing to learn along the way and hopefully some of you out there have some knowledge to help me on my way of understanding, now onto my post . . . .

All this talk about DAQ software had me thinking this past weekend about my manual dyno, especially after doing a simple dyno pull on Saturday and having trouble watching everything. I started doing a little research on just what it would take to make myself a DAQ for the dyno.

I have one of those cheap DAQ cards from Dataq Instruments (DI-194) that I picked up some time ago and it motivated me to do some net surfing on what I could turn up. Seems I have most of what I need already in my panel meters. They output analog signals or can be upgraded for it, except the tach which from my research I would need a freq-to-volt converter such as the LM2917 chip. My torque meter does not have analog output but I do have another meter here that does or I could build a circuit using a INA125P chip. My thermocouple meter outputs an analog signal of 1mv/degree.

The Dataq board uses 0-10 volt signals and has 4 channels, so if I can get everything up to that range can I make a simple DAQ setup? I'm looking for something that will capture the data and allow me to analyze it later. My current idea was going to be a camcorder setup to read my display for later playback . . .

Knowing all of this what can I do? (please be gentle)

[Peter]

Bruce,

The question is not what you can do, but what do you want to do. As you know I have a SF-901 Dyno, so I can record most of what I need with the software from Superflow.

The key is knowing what you want to record, torque, rpm, egt, O2 maybe, oil pressure, oil temp, water temp, fuel pressure, fuel flow, air flow, air temp and weather conditions.

The HP, BSFC and other requirements can be calculated from the above through simple math. So my question is what do you want from your dyno and what can you record.

Peter

[Nick]

I have looked into this a little myself, here's what I know and maybe it will help. You have to figure out a way to calculate the inertia of the dyno. If you did step test I would say you could go through the data and pick out the numbers you wanted and graf them in an excel sheet.

PT makes the data dyno setup that you could get working for probably 600-800 bucks.

Land and sea makes a board ($500) and program ($500) that would work good to, called dyno data lite.

Both would let you do acceleration tests and adjust for the inertia of the dyno.

After several emails to Depac, they seam to have the best dyno hardware and software out there. I was looking at about $4000 just to get started.

That video camera does not look so bad. But to have usable results you ll have to step test.

I'm sure there are others who have a lot more experience than me with this.


JMO

Nick

[bruce]

Currently my dyno is able to read rpm, torque and egt. For right now this is a start and what I have to work with. Yes sometime down the road I'd like to add additional sensors but for right now budget dictates what I have.

My first post states what I can get in analog output from these readings, from that I want to be able to log that info, simple data logging is what I am after right now. Hope that clarifies my goals at the current time . . .

[Peter]

Bruce,

Take a look at this site;



With the LM-1, an AuxBox and LogWorks software, you should be able to record what you need.

[86rocco]

[bruce]

I appreciate all the replys, thanks!

My dyno is an eddy current dyno so it allows me to perform steady state testing, I know the inertia so I could also do acceleration testing or sweep(?) testing. Mostly my plans are for steady state testing at this time.

I'm not able to buy a professional setup from a known company nor would I want to do that at this time, for me its more about learning something along the way. I guess what I am going to have to do is watch ebay for a DAQ card, build my amp circuits, hook it all up and see what happens. From what I can tell I have a good plan I just need confidence it will all come together.

In the mean time I'll just do everything manually . . . thanks again everyone for thier ideas!

[Tony]

Bruce, there are really two quite different problems to think about here, controlling the dyno itself, and monitoring all the instruments.

Right now you have a throttle and a load control, and it is probably fairly difficult to control even those simultaneously by hand, let alone read any of the instruments at the same time !!

My first step would be to be able to control the dyno load automatically so you can do some static tests. Have it so you can set a particular Rpm, and then open up the throttle all the way, and have the dyno hold those exact Rpm. You can then read your instruments at leisure, and "log" the results with a pencil and paper.

Throttle down, set a different Rpm and do it all again. That will enable you to plot static power and torque curves. It may not be ideal, but it would be a step in the right direction, and reasonably repeatable.

Logging a whole bunch of stuff when you cannot even hold the Rpm or load steady may not really tell you much. So how about concentrating on controlling the dyno load first of all ?

What you need is for the dyno load to increase very steeply at some particular Rpm, and hold that Rpm, where you can then measure torque.

[blown928]

Bruce,

I'm using the 194 for my KISS bench (which is getting REAL CLOSE NOW!). I've developed an excel spreadsheet with a VBA module to read the 194, apply the calibration factor, put the data up on the screen, and let me grab data into the spreadsheed when I click. It's all working pretty well, and I'm going to post the spreadsheet to the forum when I polish it up a bit.

The Dataq software that comes with the unit will allow you to record and store 4 channels of analog data to your hard disk. You can run 2 194RS units on one computer, so you can record up to 8 channels of data. As you said, if you can get all the signals into the 0-10V range you'll be able to record them with the 194. There is a waveform viewer that also comes with the 194 that allow you to browse the recorded waveforms. It's pretty good for $25, eh?

Bill

[Scott]

I too have been hashing over ways to cheaply apply a load control to a dyno.How could you set up a stepper motor so it gets its input from ignition pulse and will let the engine accellerate at 600 rpm/sec. I could easily machine all of the required components, but, the stepper control/software is over my head at this time. The systems would be similar, Bruce is probably using some sort of Pot. and I'm using Crack, er, I mean a valve to control the loads. All of you non Pot/Crack heads please chime in......

RRBD

[bruce]

An update, I talked to Dataq and they confirmed what I proposed would work. I have no, zero, 0, zilch programing experience so those of you who know VBA would now be my "best buddies"

I will keep my load control manual for right now but could setup a servo to control my variac later on down the road. My main concern is capturing the data flow and logging it. The 194 also will allow me to trigger logging via a switch on my throttle or load control so I don't gather alot of extra data I don't want. 4 channels will be all I need for right now, from what I was reading on the 194 I might also be able to read rpm's without converting to 0-10v? I just purchased a new thermocouple meter that has analog output of 0-10v so all I need now is my torque in 0-10v. If not I am prepared to make up amps for the conversion for freqs and mv/v.

Yes if it all works $25 is not a bad deal even without a VBA application.

[Scott]

How would you do the Rpm thing, Digital channel? What are you using for a pick up? A prox switch?

[bruce]

I am using a Red Lion Control inductive pickup with a 30 tooth gear for a trigger. I was reading on the dataq support forum about being able to read freq depending on your pickup voltage output. Not sure what mine is outputting so I am not sure on all that much yet. I plan on playing with it tomorrow sometime, I have a dyno pull to do and figured I'd hookup my digital volt meter to get an idea of my output voltage, like I stated earlier this is out of my realm of knowledge on any of this so its "learn as I go".

I do know what positive and negative is . . .

[blown928]

The f-to-v chip would probably be the best way to go with your RPM. You should be able to get started with the software Dataq supplies, no vb needed. Once you get farther along if you need some programming talk to me, I have a need for a 'best buddy' with a machine shop

[bruce]

I agree on the f-to-v chip, I looked at the application notes on the LM2907/2917 chip and see they have a circuit that does a two-shot output freq. This should work quite well with my 30t trigger wheel since I am getting 30hz out of that. No sense in making this more complicated than I can understand trying to get the 194 reading freq output.

With the load cell amp a question arises with the INA125 chip and precision reference voltage, my Omega panel meter supplies the reference voltage to the load cell now, so can I just feed the output signal from the load cell into this chip without the chips reference voltage, so I would be using the chips amp but not the ref voltage? (Hope that makes sense)

Yes, I need to walk before I run (VBA) with the Dataq setup.