Single microcontroller execution of control and safety system functions in a dialysis machine
US5618441A · kind A · utility
Inventors
Key dates
| Filing date | Jun 7, 1995 |
| Grant date | Apr 8, 1997 |
| Priority date | — |
| Expiry date | Jun 7, 2015 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S706/924
- WIPO fieldChemical engineering
- WIPO sectorChemistry
Abstract
A dialysis machine uses a single microcontroller to perform both safety system functions and control system functions. A single segmented memory records the safety system code and data separately and in isolation from the control system code and data. Access to the safety system software is limited to the operating system and safety system contexts. A protected mode of operation of an embedded processor allows recovery of a state vector upon failures of the operating system, the safety system and the control system. The operating system allows recovery of a state vector upon failure of the safety system and the operating system. A watchdog timer circuit places the dialysis machine in a safe patient state if a total failure of the microcontroller occurs. This functionality assures that the machine is placed in safe patient state under failure conditions and that the safety system software is isolated from the control system software to avoid having to re-validate the safety system when control system software changes are made.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.