Sequence controller with combinatorial Boolean logic
US5265004A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Oct 15, 1991 |
| Grant date | Nov 23, 1993 |
| Priority date | — |
| Expiry date | Oct 15, 2011 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG05B2219/13009
- WIPO fieldControl
- WIPO sectorInstruments
Abstract
A programmable controller for sensing the status of input devices and controlling the state of operating devices in accordance with a stored ladder logic control program includes a state machine instruction. A memory is provided for storing data regarding each state of an apparatus being controlled. This data defines the status of apparatus operating devices for each state, and the legitimate transitions from that state to other selected states, along with a Boolean logic expression of selected input conditions which determines when a state transition should occur. A processor responds to the state machine instruction by examining the truth of the Boolean logic expressions for the present state of the apparatus to detect if a state transition should occur. Upon such a detection controller advances to the state associated with the detected true expression. State transitions also can be defined as occurring upon a specified change in the status of a single input. Other mechanisms are provided to detect illegitimate states of the apparatus and take appropriate action.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.