# calculate rate of change

Discussion created by appanar on Nov 15, 2011
Latest reply on Nov 17, 2011 by appanar
I am trying to calculate in PI Processbook the rate of change for a PI tag in minutes using the last value and either the second last value or the last 30min average. I then want to use the information to calculate how long in minutes it would take the PI tag to reach the limit. The limit is specified using a dataset. I would like to calculate the rate of change for all types of PI tags i.e. Flows, levels,pressures, temperatures etc. I want to display the value on the trend symbol for the panel man to take action. e.g. "Action required within", 5, "mins" Is there a macro that can be used in PI processbook to do this? Regards, Ram Appanah