We are trying to programmatically delete past values that occur on the hour, each hour, using a simple Python script. Most values should remain, only those that occur on the hour should be deleted. I could not figure out the permissions for deleting entries, so as a workaround, I set the program to periodically overwrite certain values with a null float, hoping that PI Vision would handle these missing values by simply not displaying them. Unfortunately, this produced the following result:
Rather than ignoring the invalid floats and drawing lines between valid data, it seems to hold the previous valid data entry, draw an 'x', and then jump to the next valid entry. Between valid entries, it correctly draws a line.
Is there any way to change how PI Vision handles invalid floats? Alternatively, is there a better way to programmatically delete only certain data? (I realize I could make a separate PI point for the data that should be deleted, but I'm hoping to consolidate this to a single PI point).