The SiloPatrol® SMU SE cable-based level measurement instrument is available with an analog 4-20mA self-powered output. This Silo Monitoring Unit (SMU) is a stand-alone transmitter that provides an updated (refreshed) direct analog signal each time a new measurement is made. Measurements are initiated either automatically as programmed within the unit electronics or as a direct response to receiving a remotely activated electrical “sound” signal. The SiloPatrol sensor can be programmed to hold the last measurement output value, to output less than 2mA or to output greater than 23mA, in the event of a sensor failure. Choosing either of the last two error signal choices allows your control system programmer to provide timely error or alarm notification by whatever means is appropriate for your plant operation.