The Walchem WDP340-5N1 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:
with 4 pulse proportional control outputs and diagnostic alarm relay, hardwired, cable glands, no 4-20 mA output, two preamplifiers (190783) w/10 ft. cables, prewired
