The Z190 is a two channel unit offering the addition or subtraction of current and voltage signals. A typical application would be two pressure sensor inputs from a holding tank, with the Z190 subtracting/adding the two pressure signals and providing an output signal relative to this calculation i.e a true level for the materials inside the tank. The Z190 can also convert the signal, from volts to mA, so the device can accept the 4-20mA pressure sensor outputs, perform it's internal addition/subtraction calculations and output a 0-10V signal for your display. It uses dip switches to set the available input/output ranges. The auxiliary power supply also allows an active or passive connection on the output.