The Walchem WPH410-5N1N 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:
on/off control outputs, hardwired, cable glands, no 4-20 mA output, preamplifier (190783) w/10’ cable, pre-wired