... and the other can be used to input current (0~20 mA, 4~20 mA).. 1 digital output terminal, 1 multifunction relay output terminal ... the other can be used to output current ((0~20 mA or 4~20 mA).. With the twinkling display of preset frequency, running ... nixie tube showing present output frequency, present rotate-speed (rpm), present output current, present output voltage, present linear-velocity ...