The issue of calculating average flow rate in the Yokogawa DCS system
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I would like to ask everyone about the issue of calculating average flow rate in Yokogawa systems. The process requirement allows specifying any time period to calculate the average flow rate. For example, to find the average traffic volume during the period starting at 2:29 p.m. three days ago and ending at 3:07 p.m., with the option to specify the time period arbitrarily. As far as I remember, there is no program interface for reading historical trends; please give me some advice.
No manufacturer has yet developed a function for reading trends, but you can implement it logically by dividing the total usage by the total time
No manufacturer has yet developed a function for reading trends, but you can implement it logically by dividing the total usage by the total time
The most important requirement is that the time can be arbitrary, which makes it impossible for me to collect data
I can offer an approach: you can use calculation blocks or sequencers, and within them reference time functions to accumulate the sample values
Thank you for your insight. My question is about how to obtain the value of a variable that represents a certain time point; especially when this time is random, it is necessary to read the value of the variable that represents that random time. Can time functions be read?
The historical trend seems to have an average value option, but the time is in whole hours
The cumulative value can be used to determine a long-term trend; by setting a smaller interval for this trend, the cumulative values at two points along the trend can be taken, subtracted from each other, and then divided by the time interval to obtain the average flow rate, which should be quite accurate.
The key point of the question I raised is how to read trends.
You can do it using the SEBOL language; there is a function called gettime that returns the current time (hours, minutes, seconds)
Thank you. After obtaining the current time, how can I get the PV value for this time?