Process variable values and setpoints are usually scaled and displayed in engineering units so that the value shown directly relates to the process.
For example a 4-20mA signal might be scaled to represent 0.0 to 14.0pH from a pH sensor or transducer. The displayed value would be 7.0 when the signal was at its mid point (12mA). Some products can display the name of the engineering unit beside the value (for example 0.7ph). Typical engineering units are °C; °F; K; bar; %; %RH; pH or psi.