Citect Trend Interpolation methods

How are you exporting the trend samples? If you export from Process Analyst, you get whatever is displayed on screen, with the number of samples/sample rate that PA chooses, and by default, only 300 samples.

If you use the TrnExportCSV() Cicode function, you can set the sample rate (Period argument) to 2sec to get the exact samples recorded in the trends. If you choose to export every 6 seconds it will have to condense 3 recorded samples into one exported sample. The iDisplayMode arguments allows you to choose the interpolation method for each trend tag. By default, if it has to condense multiple recorded samples into one exported sample, it uses the mean value of those (3) samples. You could use Condense Mode 12 to get just the newest sample, if that's what you want. See the TrnExportCSV() help:

thank you for your reply.

We are using CSV_Include project and its poptrend template in XGA resolutions. nevertheless yours and MARCO's explanation clearly help to understand the visualization behavoir of the trends.

Im my case sampling period of the trend configured is 2 Sec. The trend we were using has defined 601 Samples per 1 pixels, which allows is to set a maximum duration of 20 minutes to view sample taken at 2 seconds.

Just another query if lower the time span for 15 minutes..Still trend retrives 601 Sample from trend file and displaying.

In this samples it showing values at 1 sec intervals as well, ideally for my trend configuration if my sample period is 2sec then values of this 1 sec intervals showb are interpolated values or calculated or what??

regards

thank you for your reply.

We are using CSV_Include project and its poptrend template in XGA resolutions. nevertheless yours and MARCO's explanation clearly help to understand the visualization behavoir of the trends.

Im my case sampling period of the trend configured is 2 Sec. The trend we were using has defined 601 Samples per 1 pixels, which allows is to set a maximum duration of 20 minutes to view sample taken at 2 seconds.

Just another query if lower the time span for 15 minutes..Still trend retrives 601 Sample from trend file and displaying.

In this samples it showing values at 1 sec intervals as well, ideally for my trend configuration if my sample period is 2sec then values of this 1 sec intervals showb are interpolated values or calculated or what??

regards

The template you're using is very old (2002?) and uses the legacy trend object (not Process Analyst). I don't believe it supports the newer Request Mode feature. It probably just uses the default request mode.

Noted your suggestions...

trend control is already updated in 2018 environment, and in trend help its mentioned when trend is defined as periodic it is showing samples at specified period.

anyways thank you for your support, I will go with the trend export cicode function to get the result..

Warm regards

Hemant