Combining disconnected discrete data trends using last good values

[Omar Fauzi]

Hello, 

I'm trending a discreet data for about 5 years period from a process unit indicating a valve opening status (1 = close, 2 = Open). When I pulled the plant data using Seeq, I found some periods which I observed "disconnected data" where it will neither shows 1 or 2. Basically, there are gaps in between the data I pulled.

I would like to combined the data together using the last good value before the data got disconnected to the subsequent available data points. May I check if any functions in Seeq I can use to ensure it will always be a continuous single data line?

 

Much appreciate for the help

 

Regards, 

Omar

[Lindsey.Wilcox]

Hi Omar-

I recommend changing the signal to be step interpolated.  This can be achieved through the Formula tool using the following syntax:

$signal.toStep(1d)

The maximum duration of '1d' indicates that Seeq should interpolate between data points spaced by 1 day or less.  When you select a maximum duration, choose a duration that is large enough to interpolate between the gaps in your data, but not so large that it unnecessarily impacts that performance.

Please let me know if you have any additional questions.

Thanks,

Lindsey

[Andrew Fontenot]

We have similar issues with some tags. In our case, the tags are already Step tags but still have gaps that are smaller then the max interpolation setting. In this case, we use $signal.validValues formula to achieve exactly what you've described.