The Walchem WDT400-54NN controller is now obsolete and has been replaced by the WDT400-54NU controller which now has integrated USB datalogging and software upgrade capability. Otherwise, both the WDT400-54NN and the WDT400-54NU have the same specifications with hardwired, cable glands, single 4-20 mA output, no electrodes.
Please click here to view and/or purchase the new replacement controller and to view literature.