US 4,152,760 A · Industrial process control system

Abstract

An industrial process control system to be used with processes which are geographically spread out over a relatively wide field area, with portions thereof located in respective zones, and wherein the process has associated therewith a large number of instrumentation elements including sensing elements and operating elements for controlling actuators such as process valves. The control system includes a central station with a digital computer which directs signals to a number of primary transmitter/receiver units each producing a swept-carrier wireless signal for transmission to a respective one of the field area zones. Within each zone are a plurality of local transmitter/receiver units similar to the primary units, with each local unit being assigned to one or more sensing elements and/or one or more operating elements. The local units continuously monitor the signals from the corresponding primary unit, and, when instructed by signals from the primary unit, carry out specified actions concenring the process element(s) assigned thereto. Actions to be taken include repositioning a process valve, changing the set-point of a controller, and transmitting back to the primary unit signals representing data needed for control of the process. The swept-carrier transmissions of the primary units are synchronized and controlled so that the carrier frequencies thereof are all different at substantially all instants of time.

An industrial process control system for use with a complex process wherein portions of the process are spread out geographically over a field area and wherein the process has a number of variable conditions to be controlled such as temperature, flow rate, and the like;

said process having therewith sensing elements for developing measurement signals reflecting the magnitudes of corresponding process conditions and valves or other actuators with operating elements associated therewith for controllably influencing selected process variables;
said process control system comprising:
(1) a central station having a digital computer for carrying out data processing steps concerning said process conditions and for producing command signals for predetermined process elements including address signals identifying any particular element and instruction signals indicating specified actions to be taken with respect to an identified element;
(2) a primary transmitter/receiver unit coupled to said central station to receive command signals from said digital computer and including:
(a) means for developing a swept-carrier output signal for transmission to said field area;
(b) means for modulating said swept-carrier output signal with data signals corresponding to said command signals;
(c) means to receive and track swept-carrier signals carrying data signals from said field area representing information to be forwarded on to said digital computer;
(d) means to demodulate said data signals received from said field area to produce information signals for said digital computer;
(3) a first plurality of local transmitter/receiver units in said field area remote from said central station, each such unit being assigned to at least one respective operating element and comprising:
(a) means to receive and track the swept-carrier signal developed and transmitted by said primary transmitter/receiver unit;
(b) means to demodulate said data signals carried by the received swept-carrier signal;
(c) function means for carrying out the actions represented by the instruction signals incorporated in said data signals including means for producing control signals to be directed to the assigned operating element;
(d) means responsive to the address signal part of said data signals to activate said function means when the address signals identify the respective local unit as the recipient;
(4) a second plurality of local transmitter/receiver units in said field area remote from said central station, each such unit being assigned to at least one respective sensing element and comprising:
(a) means to receive and track the swept-carrier signal developed and transmitted by said primary transmitter/receiver unit;
(b) means to demodulate said data signals carried by the received swept-carrier signal;
(c) means for transmitting a swept-carrier signal to said primary transmitter/receiver unit to be received and tracked by said receiving means of said primary transmitter/receiver unit;
(d) means to modulate said swept-carrier signal with data signals reflecting the measurement signals developed by the assigned sensing element;
(e) means responsive to the instruction signal part of said data signals for developing transmit control signals to activate said transmitting means to transmit the data signal modulated swept-carrier signal;
(f) means responsive to the address signal part of said data signals to activate said transmit control signal means when the address signals identify the respective local unit as the recipient.

17 more elements

Industrial process control system

Life of this patent

Industrial process control system

Life of this patent

Abstract

Claims31