Calibration of channels in parallel

[Simon-lee]

Labview 2015
Windows 7

I’m familiar with using MAX to acquire and calibrate a signal and the ability to print a calibration Cert and flag up when the channel needs recalibrating is really useful.

My problem is I have to calibrate 6 k-type thermocouples between minus 76°F and plus 194°F.  6 off probes plus the reference inserted into a ali block this is placed in the environmental chamber and a range of temperatures are set.
At each temperature 7 readings are taken and so on. It takes about two days but low temperature calibrating is slow hence the need to calibrate all probes simultaneously.
So I’m calibrating 6 channels in parallel but I can’t find a way in Max to do this as Max wants me to calibrate one channel at a time.

Any recommendations because to date the best I’ve managed is a sub-vi containing multiple function blocks but this seems a little crude and loses the useful bits. The other alternative I rejected was to just treat the K-type as a mili-volt signal but I suspect that isn’t a good idea.

So how do you guys handle calibrations - any tricks or techniques you can share 

[James.M · Accepted solution]

You can calibrate multiple channels in MAX buy holding shift and selecting the last channel to calibrate, or by holding ctrl and selecting individual channels.

If you want to do this in LabVIEW instead, share the code that you've tried and we can help you improve it.

[Simon-lee]

Thanks for your advice,

Your description was spot on and I've identified  where I slipped up. 

I would be very interested to see how a professional would handle calibration within  Labview, especially the areas of password protection and forcing recalibration after a predetermined interval.

I have attached a very primitive proof of concept to represents  what I trying to learn, please forgive the write to file mess as I'm struggling to understand time base needed to create a useable excel file.

[James.M]

A professional would do away with the express VIs. These are great for quick development but have very little functionality and can often lead to issues.

The Task control stuff you're doing in MAX can all be done using LabVIEW DAQmx VIs and you can actually see this done really easily by right-clicking your express VI and selecting Generate NI-DAQmx Code. On top of that code, you would need to work with the other DAQmx VIs to do calibration.

As far as password protection, if you can think of a way to do it, you can build that password in anyway you like. This could be prompting the user for a password when they click a button and then continuing to a relevant interface if correct, or just prompting for a password on application start.

Professionals in LabVIEW follow suggested LabVIEW architectures and guidelines. The main ones are the State Machine and Producer Consumer, which can be adapted to "Simple State Machine" and "Queue'd Message Handler", which you'll find in your LabVIEW project templates.

If you plan on using LabVIEW more thoroughly, I would suggest following some tutorials to learn what LV is capable of before continuing.

"Give me six hours to chop down a tree and I will spend the first four sharpening the axe."  - Abraham Lincoln

Here are some free training tools primarily focused on LabVIEW and NI hardware to help get started.

NI Learning Center

NI Getting Started

-Hardware Basics

-MyRIO Project Essentials Guide (lots of good simple circuits with links to youtube demonstrations)

-LabVEW Basics

-DAQ Application Tutorials

-cRIO Developer's Guide

Learn NI Training Resource Videos

3 Hour LabVIEW Introduction

6 Hour LabVIEW Introduction
Self Paced training for students
Self Paced training beginner to advanced, SSP Required
LabVIEW Wiki on Training

[Simon-lee]

Thanks for the advice and the study list,

Guess I know what i'm doing over Christmas 🙂