What is Process Variable (PV)?

Process Variable is the parameter that is to be indicated and/or controlled. It is monitored by the main process input of the instrument.

Common types are Thermocouples, PT100 or other RTD temperature probes; %RH, pressure, level, flow etc from transducers that convert these parameters into DC linear input signals (e.g. 4 to 20mA). Linear signals can usually be scaled into engineering units.