METHOD FOR DETERMINING THE STATE OF A FIELD MEASURING INSTRUMENT FOR PROCESS AUTOMATION AND PROCESS INSTRUMENTATION, AND FIELD MEASURING INSTRUMENT FOR CARRYING OUT THE METHOD

摘要

The aim of the invention is to systematically record the influence of an individual adverse influence quantity or of a combination of adverse influence quantities on the serviceable life or operability of a field measuring instrument and to be able to better estimate the serviceable life or operability of the field measuring instrument. To this end, at least one relevant influence quantity, preferably several, is/are evaluated. In addition to a measured value (24) for a process variable, other quantities (25) and (26) are recorded by corresponding sensors placed on or in the field measuring instrument and are preprocessed in analog format in appropriate operating circuits in order to then digitally record them with the same A/D converter (21) that also records the measurement signal A for the process variable. The desired input signal can be selected via a multiplexer (22) and is then further processed with the aid of a microprocessor (23). As a result, the combined effect of the different influence quantities is determined and a remaining estimated serviceable life is calculated. The microprocessor (23) can trip an alarm signal in the event critical values arise in the recorded influence quantities (25, 26).