Improved automatic function selecting multimeter.

摘要

A digital multimeter having automatic function selection capability includes a signal type detector and an analog-to-digital converter formed as an application specific integrated circuit. The signal type detector has a comparator circuit that compares the analog input signal to be measured with predetermined thresholds and stores the resulting values, which are related to the type of analog input signal, in a memory that is also a part of the signal type detector. A controller executes an automatic function selection program that causes the controller to read the stored values and generate a corresponding function code, which causes an analog-to-digital converter to be configured to perform an appropriate conversion function on the analog input signal. When a change in the type of analog input signal is sensed, the controller aborts the present measurement cycle and proceeds with a next measurement cycle in which the changed analog input signal is measured. The controller also produces a change alert signal to indicate that a change in signal type has occurred. <IMAGE>