The Walchem WPH410-321U 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, on/off control outputs, 120 VAC, pre-wired WPH420 with 10’ cables, with (2) e90495 connectors for ew pumps, two isolated analog (4-20 mA) outputs, preamplifier (190783) w/10’ cable, pre-wired, integrated datalogging and config file import/export via USB flash stick.