In a system in which a continuous, periodically repeated, pulse duration type signal is utilized to transmit information to a computer, the pulse duration type signal is converted into a series of clock pulses. The clock pulses are then counted for a period of time equal to the repetition period of the pulse duration type signal. This count is then latched and transferred to the computer to thereby accomplish the transfer of information to a computer by means of a continuous, periodically repeated, pulse duration type signal.
An apparatus for monitoring the operation of a measuring unit for obtaining information related to a predetermined parameter. The measuring unit provides an indication of said information having been measured, which can take the form of an indicator lamp, for example. The measuring unit includes a mechanism for inhibiting operation of the indicator for a predetermined time interval, after the elapse of a time period which is related to the information obtained by said measuring unit. The monitoring apparatus measures the length of time of the time period and provides an indication of the time period measured, preferably in terms of the monitored parameter. The disclosed invention is particularly suited to the monitoring of an distance measuring unit or a photometric unit for an automatic camera so that proper operation of such units can be confirmed without having to disassembly the camera.
