... FT16 Frequency digital Tachometer FEATURES:1). One meter with multi-function, frequency, tachometer, line speed meter selected by software2). ... be optional.6). With analogue output signal 4 ~ 20mA, can be with RS-485 communication function Power supply100 ~ 250V AC, ... : 0 ~ 50°C, Humidity: 35 ~ 85%RHInput signalSquare wave, sine wave signal: 5V≤High level ≤ 30V, 0 ≤Low level ≤2VInput impedance ...