The Walchem WDP440-12NU controller is now obsolete and the closest equivalent is the WPH600 controller. The new WPH600 series has upgraded features; for reference, here is the description of the old model:
pH/ORP controller, with 4 pulse proportional outputs & 1 dry contact dedicated alarm, 120 VAC, pre-wired with 20 ft. cables for E Class pumps, two isolated analog (4-20 mA) outputs, no electrode, integrated datalogging and config file import/export via USB flash stick.