Protected input/output circuitry for a programmable controller
US4628397A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 4, 1984 |
| Grant date | Dec 9, 1986 |
| Priority date | — |
| Expiry date | Jun 4, 2004 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG05B2219/34178
- WIPO fieldControl
- WIPO sectorInstruments
Abstract
Input/output circuitry is disclosed for use in an I/O system of a programmable controller. The circuitry is protected against overcurrents without the use of fuses or circuit breakers, and is automatically restored to normal operation following correction of an overload condition. Diagnostic signals are produced for monitoring the operating condition of the circuitry. The invention includes an insulated gate transistor (IGT) having a main current section carrying a majority of the load current and an emulation section which carries a fractional portion of the load current. The emulation section current tracks the total current at all times. A current sensor monitors the emulation section current and provides a signal representing the instantaneous load current. This signal is continuously compared with preselected reference levels to derive a set of diagnostic signals that are indicative of the operating condition of the circuit, and whether output loads are open or shorted, for example.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.