... encoder/switch/other signals for measurement of RPM,HZ,line speed,level 4/5/6 digit display. Digital RPM Tacho meter ... (square wave,triangle wave,proximity switch,photo switch or AC voltage)volt signal, contact switch, encoder, etc. Or power ... RTD), Panel Meter, Sensor Meter, inductor, Power Meter, Coulometer, Voltage Meter, Ampere Meter, Counter, Tacho Meter, Frequency Meter, flowmeter,Timer ...