The instrument with 96mmx48mm bezel and plug-in controller module visualizes and controls variables in analytical measurement (pH value, redox voltage, conductivity, high-purity water, oxygen, free chlorine, chlorine dioxide, ozone etc.). The indicator has two analog and two logic inputs. The first analog input is suitable for connecting a 0(4)—20mA signal, which can be provided by any type of transmitter (including 2-wire types). The input signal is conditioned, as determined by the configuration, and displayed. One special feature of the instrument is that the calibration procedures for pH, redox and conductivity are internally programmed. The second analog input can be used to connect Pt100 or Pt1000 resistance thermometers. The instrument features two 4-digit 7-segment displays for indicating the main variable (red) and the temperature (green). The temperature display is switched off in the default setting. A separate temperature sensor (Pt100 or Pt1000) can be connected to the second analog input. This can then be used to display the temperature of the medium and, if required, monitor it by means of a limit switch. During programming, the displays provide comments on the inputs. A great variety of control tasks can be handled by the various output options (relay contacts and / or analog outputs). The two relay “make” contacts that are provided on the instrument as standard can be configured as a limit controller and / or pulse width or pulse frequency controllers, or as a modulating controller. To obtain analog (continuous) controller outputs, the optional analog outputs must be configured accordingly. All controller outputs can be configured for a P, PI, PD or PID control action. In the basic version, the instrument provides two relay “make” contacts and one logic output (0/5V). Two additional outputs can be, according to choice, fitted with relay changeover contacts and / or analog outputs (process value output or analog controller output), or with a serial interface (Profibus-DP or MODbus/Jbus protocol) and/or a supply for 2-wire transmitters.