Abstract: A control system (10) controls transfer of electronic signals to and from industrial and scientific equipment. The control system includes a real-time database (60) for storing data elements which may be accessed by a plurality of tasks (62, 64, 66, 68, 70, and 72). Each data element in the real-time database (60) has an associated changed status flag for each task which indicates whether the value of the element has changed since the last access by the task. Individual tasks must communicate through the real-time database, since no inter-task communication is supported. The tasks support bidirectional communication with industrial and scientific equipment, alarm supervision, data logging, real-time clock functions, mathematical and logical functions, and interactive operator communications.

Abstract: A control system (10) controls transfer of electronic signals to and from industrial and scientific equipment. The control system includes a real-time database (60) for storing data elements which may be accessed by a plurality of tasks (62, 64, 66, 68, 70, and 72). Each data element in the real-time database (60) has an associated changed status flag for each task which indicates whether the value of the element has changed since the last access by the task. Individual tasks must communicate through the real-time database, since no inter-task communication is supported. The tasks support bidirectional communication with industrial and scientific equipment, alarm supervision, data logging, real-time clock functions, mathematical and logical functions, and interactive operator communications.

Abstract: A communications network includes a system multiplexer (10) for effecting communication channels between a plurality of peripheral units. The peripheral units include master computers (12), (14) and (16) and various slave devices such as printers (28) and display terminals (26). The multiplexer (10) includes a receive multiplexer (30) and a transmit multiplexer (32) connected together through a communications link (34). The multiplexers are controlled through control logic circuitry (36) which receives signals from a CPU (42). The CPU (42) stores a connection pattern in the control logic circuitry (36) and alters this connection pattern to change the communications link between various peripheral devices. By multiplexing the channels, real time communication is achieved.