Data acquisition - scaling thermocouple

[TobyETO]

GerdW,

Ah HA!

i did not know that!

i have switched to read voltage and things are looking at lot more stable. but now there is no scaling option for degrees C.

I guess now my problem is figuring out how to scale to degrees C from voltage.

Is there a handy labview element to do this?

Toby

[GerdW]

Hi Toby,

see the scaling functions in the numerics palette…

[TobyETO]

GerdW,

Thank you for spotting the issue with the read units.

Much appreciated!

i will play around with the scaling and settings to get this looking nice!!

Thanks to the others for assisting too!!

thanks again!

Toby

[RTSLVU]

---

@TobyETO wrote:

GerdW,

Ah HA!

i did not know that!

i have switched to read voltage and things are looking at lot more stable. but now there is no scaling option for degrees C.

I guess now my problem is figuring out how to scale to degrees C from voltage.

Is there a handy labview element to do this?

Toby

---

There is a little bit more than scaling involved in reading thermocouples.

Are you not concerned about measurement errors caused by not having any Cold Junction Compensation? 

[TobyETO]

GerdW,

Yes, there is a lot more, but at the moment I am learning the environment of labview so doing one thing at a time.

Now I want to display the data in a suitable chart. At the moment I am experimenting with the different acquisition modes, rates, samples to see what will give the most clear chart with a bit of history in the graph. i can set it up nicely, but the time scale is only a few seconds and I want the resolution to be a bit bigger, so the entire response of a temperature change can be seen on the chart.

Once I get the data presented in the right format I will then look at noise filtering, errors, and recording a step response to a file.

If you could point me in a good direction for presenting the data in a chart i would appreciate that!

BRGDS

Toby Russell

[cbutcher]

The length of a chart can be changed by right clicking on it and setting the "Chart History Length..." (the ellipses in LabVIEW generally indicate that clicking the menu option will open a new dialog).

This is a number of samples - so the duration depends on your sampling rate.

Choose an appropriate sampling rate, do any averaging/filtering you want to reduce the sample frequency, then put this decimated (or not) data in your chart and it will use some of your points.

When you fill the chart history, it will begin to overwrite the oldest samples (although the visual effect can be chosen from 3 options: Chart Update Modes Demonstration).