Fast programmable scan logic controller method and apparatus

A programmable controller for controlling physical devices, comprising:

• (a) means for periodically evaluating a set of normal equations at a first rate to produce output values for physical output interfaces producing control signals for at least one physical device;
• (b) means for periodically evaluating a set of fast-scan equations at a second rate greater than the first rate to produce output values for selected of said physical output interfaces;
• and
• (c) means for selectively controlling the selected physical output interfaces in response to the output values determined in response to said fast-scan equations and the output values determined in response to said normal equations.

An apparatus for controlling physical output devices, comprising:

• (a) a programmable logic controller for periodically evaluating normal equations to produce a plurality of first output values for physical output devices, the programmable logic controller producing said first output values at a first rate:
• (b) at least one input/output rack, which includes:
• (i) at least one physical output interface for applying a control signal to a physical device in response to an output value;
• (ii) an intelligent bus adaptor, which includes:
• (A) means for receiving at least one of said plurality of first output values produced by the programmable logic controller;
• (B) a processing unit for periodically evaluating at least one fast-scan equation to produce at least one second output value for controlling said at least one physical output interface, the processing unit producing said second output value at a second rate greater than said first rate;
• and
• (C) means for selectively transferring one of said first and second output values to said at least one physical output interface.