A logic function in which an input signal to the latch module causes the module's output to turn "on". The output remains on until a signal is applied to a second input to reset the latch. The "latch" function is usually implemented in a hardware module or PLC software. The on-board microprocessor in the SUPERPROX® Model SM502 Series dual-level control sensor models performs a stand-alone On/Off logic latch control with respect to a preset high and low limit switch point. This eliminates the need for any external control relay or programmable controller program logic to perform either a pump-in or a pump-out level control application. In the pump-in mode, the sensor output latches On when the level drops to the low level limit and latches Off when the level rises to the high level limit. In the pump-out mode, the sensor output latches On when the level rises to the high level limit and latches Off when the level drops to the low level limit. The diagram preceding illustrates the On/Off relay latch control logic emulated by a SUPERPROX® dual-level control sensor.