HM207.26A adjusts the speed of a system sending a signal ON / OFF. The speed which is read is compared with the set-point and an analog output is provided to control the speed adjust of the system. The instrument may be set as a speed adjuster or as a tachometer which generates an output in voltage being proportional to the speed which is read; in this last case the programmings related to the speed adjusts are ignored. In case of speed adjuster it is possible to select 31 different set-ponti speeds from digital inputs. The instrument is suitable for a wide variety of applications where a speed or a time value has to be displayed. In particular this instrument has already been used in the marble sector (blocks cuttering, bridge milling and looms), in the paper and plastic application fields and in the tunnel owens for drying or quenching.