The SW12V provides a mechanism for older dataloggers that don't have a switched 12V port to control power to the HMP45C. The SW12V is recommended for applications where the HMP45C will be measured by a CR500, CR510, 21X, CR7, or a CR10 with a silver wiring panel.
History: prior to May 2004, the HMP45C cable included a switching circuit that switched power to the sensor only during measurement, fhus conserving system power. Effective 3 May 2004, the switching circuit was removed from the HMP45C cable. The redesigned HMP45C connects to the datalogger's switched 12 V terminal. Dataloggers that do not have a switched 12 V terminal (i.e., CR500, CR510, 21X, CR10 with a silver wiring panel, or a CR7) can use a SW12V Power Switch Assembly to switch power to the HMP45C.