The Walchem WDP410-14NN controller is now obsolete and the closest equivalent is the WPH600PSSAN-NN controller. The new WPH600 series has upgraded features; for reference, here is the description of the old model:
with 4 on/off control outputs and diagnostic alarm relay, 120 VAC, pre-wired with 6” pigtails (if on/off) or with 10’ cables for e-class pumps (if pulse), single isolated analog (4-20 mA) output, no electrode