Programmable control apparatus and method

Apparatus for controlling the operation of a machine in response to a program of operation including a sequence of instructions defining a mechanism cycle of operation, the instructions relating sensed conditions of input devices, selectable conditions of output devices and variable values, and the input and output device conditions being represented by unique interface signals representing conditions of unique interface circuits associated with the input and output devices, the apparatus comprising:

• (a) means for storing the sequence of instruction signals representing the instructions of a mechanism cycle of operation, the instruction signals including variable name identifier signals representing memory locations of variable name signals associated with unique interface circuits;
• (b) means for storing a cycle status signal representing the executability of the sequence of instructions;
• (c) processing means responsive to the instruction signals and the status signals for executing the instructions so long as the status signal represents an executable condition;
• (d) means responsive to the unique interface signals, variable name signals and the processing means for altering the condition of a selected unique interface signal associated with an output device, thereby controlling the output device;
• (e) communication means for exchanging message signals with a data communication device;
• and
• (f) means responsive to the message signals for selectively reassigning a unique interface circuit to a variable name signal irrespective of the condition of the status signal, the reassignment being effected concurrently with execution of instructions of the mechanism cycle.

A method for controlling the operation of a system defined by a plurality of mechanism cycles of operation, each cycle being defined by a plurality of instruction sequences relating sensed conditions of input devices, selectable conditions of output devices, and variable values, the input and output device conditions being represented by unique interface signals, and the method comprising the steps of:

• (a) storing a plurality of instruction signals representing the mechanism cycles of operation;
• (b) storing a plurality of mechanism cycle status signals, each status signal representing the executability of the sequence of instruction signals associated with a mechanism cycle of operation;
• (c) executing instruction signals to produce new values for unique interface signals associated with output devices when the status signal indicates that the instruction sequence is in an executable condition;
• and
• (d) selectively adding, deleting, and modifying an instruction sequence for which the status signal represents a nonexecutable condition, of the instruction sequence the adding, deleting, and modifying of the nonexecutable instruction sequence being effected concurrently with execution instructions of executable sequences.