The process display PA 450 has been designed for the subtraction of two independent Analog signals. Due to the integrated transmitter power supply the wiring requirements are considerably reduced. The difference or the individual value of the respective transmitter is shown on the 4-digit LED display. About the user-friendly menu system the device simply can be configured. It has functions, such as access protection, configuration of advertisement and contacts, minimum / maximum value memory. The set parameters are being stored in an EEPROM and are being kept also in case of power breakdown. Optionally the PA 450 can reamed with one or two contacts and square root Analog signal.