The system controller can be coupled to various sensing devices to monitor certain variables or physical phenomena, process the variables, and output control signals to control devices to take necessary actions when {HEAD ~ the variable levels} exceed or drop below {TAIL ~ selected or predetermined values} 
drop below
The system controller can be coupled to various sensing devices to monitor certain variables or physical phenomena , process the variables , and output control signals to control devices to take necessary actions when { HEAD ~ the variable levels } exceed or drop below { TAIL ~ selected or predetermined values }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL