The Walchem WECT410-5N2U controller is now obsolete and the closest equivalent is the WCT600 controller. The new WCT600 series has upgraded features; for reference, here is the description of the old model:
Cooling tower controller -bleed & feed w/ 2 biocides and alarm, hardwired, cable glands, no analog (4-20 mA) output, electrodeless conductivity sensor & flow switch manifold on pp panel, 5 ft cable, data logging and configuration file capability.