Abstract: A self-power down circuit for a controller coupled to a battery to obtain power from the battery. The controller has a port, the state of which changes during powering up of the controller. The circuit includes a first switching device including a main current conducting path and a control terminal. The control terminal of the first switching device is coupled to the port for monitoring the state of the port. The circuit further includes a second switching device including a main current conducting path and a control terminal, and a switch. The port is coupled to the battery through the main current conducting path of the second switching device. The control terminal of the second switching device is coupled to the switch for actuation by actuation of the switch. The control terminal of the second switching device is also coupled to the main current conducting paths of the first and second switching devices through first and second voltage dropping elements, respectively.

Abstract: A serial data interface includes a receive data terminal, a received serial data out terminal and an operating power supply terminal. A zero-power receive detector for the serial data interface includes a source for furnishing operating power to the interface. The supply of power from the source is controlled through a microcontroller for switching power to the interface. The microcontroller is coupled between the source and the operating power supply terminal of the interface. A light source portion of an optical isolator is coupled to the receive data terminal, and a light activated switch portion of the optical isolator is coupled to the microcontroller.

Abstract: A system is provided for adapting one of a number of different types of instruments to a common protocol. Each instrument has a serial input-output (I/O) port, a control for the serial I/O port, and an input for operating power to the instrument. The system includes a different type of housing for each different type of instrument. Each different type of housing includes openings through which selected controls and displays of a respective one of the instruments are accessible. Each different type of housing includes couplers for coupling to a respective type of instrument's serial I/O port, and to a respective type of instrument's operating power input, and a data processing module including a first multiple conductor. Each type of housing includes a complementary second multiple conductor connector for connecting to the first multiple conductor connector when a respective housing is mated to the data processing module.