Chemical process control system

Abstract

A chemical process control system includes a plurality of sensors for sensing various parameters of several baths employed in a chemical process. A microprocessor is employed to interrogate each sensor, to determine bath characteristics from one or more of the parameters, and for comparing the parameters to established limits. The microprocessor initiates corrective responses whenever a characteristic falls outside its specific limits in an attempt to restore the characteristic to a specified operating target value. A hierarchy of authorization keys limits access to the apparatus depending upon the level of authority of the person seeking access. Different degrees of authority may be delegated for an apparatus operator, a supervisor and servicing personnel. The apparatus includes a local and remote communication capacity for sending messages concerning malfunctions in the apparatus and for receiving instructions from a remote location for correcting malfunctions. The microprocessor controls the sensors through a plurality of 'slots' through which drivers for specific sensors are controlled. The microprocessor controls sensor operation through non-sensor-specific signals that employ an address table to provide sensor-specific signals to the sensor drivers through at least some of the available slots.