... + LED diaplay 2. RS485 port. 3-phase AC Voltage / Current Combined Panel Meter:IntroductionYD912X Three Phase AC Voltage/Current Combined Digital Panel Meter measures and ... AC voltage/current measurement device.Model DescriptionYD9120:3 phase current, voltage input, 4 bits display,YD9121:3 phase current, voltage input, 4 bits display + one RS485,YD9122:3 phase current, voltage ...