RTU Radio Modem with 4-20 mA Current Loop, Serial, Discrete, Pulse Counter and Modbus I/O. The WISE 4-20 Radio Telemetry RTU is available in the 150 MHz (VHF) and 450 MHz (UHF) licensed frequency bands with up to 4: 4-20 ma analogs (24 bit), 8 discretes, 1 pulse counter or 1 serial interface. WISE Host unit has mirrored I/O or is also available with a serial port, allowing remote site monitoring and control using Modbus.