Accepting 2 electrode signals in any combination of pH and ORP, Series WDP400 dual input pH/ORP controllers are designed for water treatment applications. There are 4 control outputs, available as on/off control relays, or as pulse proportional outputs to directly drive electronic metering pumps. Each control output can be assigned to either electrode, and relays can be either high or low set point, high or low alarm, in range alarm, out of range alarm, or probe wash.