The Walchem WDP420-1NNN controller is now obsolete and has been replaced by the WDP420-1NNU controller which now has integrated USB datalogging and software upgrade capability. Otherwise, both the WDP420-1NNN and the WDP420-1NNU have the same specifications with 2 pulse proportional relays & 2 on/off dry contact relays & 1 dry contact dedicated alarm, 120 VAC, pre-wired with 20 ft. cables for E Class pumps, no 4-20 mA output, no electrode, no USB.
Please click here to view and/or purchase the new replacement controller and to view literature.