Calculating Sample to Sample Changes

[Ted Williams]

Hello,

Using Seeq Tools, are there ways to easily calculate the change in value from one sample to the next, as well as the corresponding sample time?  These types of calculations can be useful in a variety of applications (e.g., tank fill/drain, irregularly spaced process samples, equipment status transitions, etc.).

Ted Williams

 

[John Cox]

Hi Ted,

The answer is yes, there are! One of the easiest ways uses the Seeq Formula editor. The runningDelta() and interval() functions provide methods for calculating changes in sample values (and the actual sample time) from one sample to the next.

For example, the change in a tank level can be calculated using this approach:

 

Giving this result:

 

This next example demonstrates the interval() function for calculating the actual sample time for each sample in a signal. The sample time interpolation and units are modified to improve visualization:

 

With the results displayed for a process sample that is collected intermittently:

 

I hope this covers all the bases for your question, Ted! Please let me know if you have any follow-up questions.

John