The answer depends what You mean by saying PV? From the answers I understood some assuming it to be the Photo-Voltaic Yield, and others as Process Variable a nomenclature used in the control systems like EPICS (http://www.aps.anl.gov/epics). If the question was about EPICS PV then I would recommend CS-Studio the most mature tool, then caQTDM, then You might want to check also old edm, medm and very old dm.