Temperature difference measurements

[Divide204]

Hi,

I've been working with LabVIEW 2018 code that allows me to activate a "Steady State" LED indicator when the temperature change is less than a certain amount (0.4 deg C/min). I'm wanting to measure the current temperature output, and then the temperature output from 1 second ago. I can't seem to get this to work. I'm using a cDAQ-9184 to record the temperature data from some thermocouples.

[GerdW]

Hi divide,

---

@Divide204 wrote:

I've been working with LabVIEW 2018 code that allows me to activate a "Steady State" LED indicator when the temperature change is less than a certain amount (0.4 deg C/min). I'm wanting to measure the current temperature output, and then the temperature output from 1 second ago. I can't seem to get this to work.

---

The reason is "THINK DATAFLOW!"

This is your VI after using AutoCleanup:

• That 2nd loop is only executed AFTER the 1st one - due to THINK DATAFLOW!
• It is also nonsense to wire the same value twice to the 2nd loop - and then subtract both IDENTICAL values to check their difference!

You need to use a shift register in the 1st loop to keep previous values for next iteration(s)!

[Divide204]

I'm trying to store the past value, and then subtract it from the current reported value. I've tried finding what a shift register is but I haven't found much useful information on how to use it properly and what it does exactly. 

[JÞB]

---

@Divide204 wrote:

.... I've tried finding what a shift register is but I haven't found much useful information on how to use it properly and what it does exactly. 

---

See here