Log 2 voltages simultaneously

[_Joeri]

Hi everyone,

I've tried the search option, and found out a bit, but not everything I'd like to know since I'm a LabView noob.

I'm a senior in college and I'm doing my thesis right now.
We've only had 5 short classes about using LabView so I'm not to familiar with it.

Now for my thesis I have to design a certain testing setup to be used in an automotive enviroment.

I'm going to use 2 podmeters, a lineair and a rotative one. I need to log these voltages simultaneously,

preferably lineair movement as a function of the rotative movement.

Since I'm a noob, I don't really have an idea how to get started, and I'm not sure what kind of interface, wiring, etc. I would need.

If you guys could help me out, I'd appreciate it.

Cheers,

Joeri

[DAD]

First, you need to determine the details of what you're trying to log, what are are voltage ranges and how fast do you need to sample them.  A lot of the NI hardware is designed to handle +/- 10 volts, but there is hardware that will handle higher ranges (or you can use resistors to create voltage dividers).  You didn't say what your major is but this might be a good opportunity to work with your thesis professor and team with someone that can compliment your area of study. 

For the software, I'd start by looking at the examples found under the Help->Find Examples... in LabVIEW.  Look in the Hardware Input and Output->DAQmx->Analog Input folder, starting with the Voltage - Continuous Input.vi example.  It will show how to acquire the voltages, but not log them.  There are examples in Fundamentals->File Input and Output for writing to disk, or you can look at the Write LVM Express VI as a quick way to log data.

[_Joeri]

The voltage ranges from 0-5V for both signals. 4-5Hz sampling or something like that should be enough.

I've asked my professor, but he's one of those that never teached technical classes and knows almost nothing about technical stuff either.

So he's not going to be of much help I think.

[ThiCop]

Hello Joeri,

We will need a bit more information to be able to help you get on the right path:

- What kind of hardware are you using to measure your voltages?

- Which version of LabVIEW are you using?

[_Joeri]

Excuse me for the late reply, I was quite busy the last couple of days.

National Instruments Belgium advised me to use the USB 6008 to read my voltages.

I'm using LabVIEW 2010 64x.

Cheers,

Joeri

[ThiCop]

Hello Joeri,

This should be possible.

One thing that seems a bit off is the following:

- I'm going to use 2 podmeters, a lineair and a rotative one. I need to log these voltages simultaneously, preferably lineair movement as a function of the rotative movement.

Is there a specific reason why you want to log it like that?

It seems more logical to log both values versus time (with the time values being the unique values).

[_Joeri]

Well the goal is to measure the valve lift (lineair potmeter) for every ° of camshaft rotation (360° potmeter).

So in this case it would be easier to comprehend and use the measured values, then to log them as a function of time.

Cheers.

[ThiCop]

Hello Joeri,

Ok, this brings me then to the next point:

What have you already tried in LabVIEW?

[_Joeri]

Well I'm still trying to figure out how i can make a graph with let's say the lineair movement on the y-axis and the rotational movement on the x-axis..

I've tried to use my exercises from classes in school as a reference but they're made in LabVIEW 2011. Since I'm working with the 2010 version, I can't open those..

Is there a way to access these?

Joeri

[_Joeri]

Okay I'm slowly figuring things out, but I can't seem to find the DAQ symbol to use in my block diagram?

Express => Input => and there should be a DAQ Assist symbol, but that's not the case..