Abstract: Methods and ultrasonic sensor systems are presented for sensing distance in which an acoustic output signal is directed toward a target and acoustic input signals are received from the direction of the target, and the received signal is compared with a selected one of a plurality of different receiver threshold curves to identify the acoustic wave travel time to the target and back while differentiating between the target and acoustic waves reflected more than once and waves reflecting off obstructions between the sensor and the target, where the user selectable receiver threshold curves are tailored for different target and/or obstruction conditions.

Abstract: A programmable controller interfaces a numerical control system to sensing and operating devices that control the auxiliary functions on a machine tool. In the controller a microprocessor is coupled to a random-access memory (RAM) and an electrically alterable read-only memory (EAROM) through an address bus and a data bus. The RAM stores a user control program and an I/O image table that depicts the status of the sensing and operating devices on the machine tool. Under program control the microprocessor verifies the contents of the RAM and copies the verified contents into the EAROM. If the contents of the RAM are altered or lost, the master copy of data stored in the EAROM is reloaded into the RAM.