The Walchem WDP420-52NN controller is now obsolete and has been replaced by the WDP420-52NU controller which now has integrated USB datalogging and software upgrade capability. Otherwise, both the WDP420-52NN and the WDP420-52NU have the same specifications with w/ 2 pulse proportional and 2 on/off control outputs and diagnostic alarm relay, hardwired, cable glands, two isolated analog (4-20 mA) outputs, no electrode.
Please click here to view and/or purchase the new replacement controller and to view literature.