I am trying to write a PIAF equation that is looking at a valve position, once the position goes to 100% open, the system is taken out of service, cleaned and returned to service. When it is returned to service the valve position is typically less than 20% open. 7 hours after the valve is returned to service I need to report a value, just at that time and not write another value until the valve has cycled up to 100% open, been cleaned and returned to service.
The part I am struggling with is only writing the single value at 7 hours after it is returned to service, how do I do this?
Thank you,
dan
