METHOD OF OPERATING AND OF PREDICTIVE MONITORING OF A FIELD DEVICE

An improved method of operating a field device (1) for measuring and/or monitoring at least one measurement variable (p) and of predictive monitoring of a compliancy of at least one characteristic of said field device (1) to a requirement specified for said field device (1) is described, comprising the steps of: continuously monitoring said characteristic by: at consecutive times (ti) determining and recording a deviation (D(ti)) between a measured value (M(ti)) of a monitored variable (m) determined by said field device (1) and a reference value (R(ti)) of said monitored variable (m), wherein said deviations (D(ti)) are indicative of a degree of compliancy to said requirement, applying a filter to the recorded deviations (D(ti)),based on the deviations (D(ti)) and the filtered deviations (FD(ti)) determining a noise (N) superimposed on the filtered deviations (D(ti)), at the end of at least one monitoring time interval (MTI) determining a remaining time (RT) remaining until the deviations (D(ti)) will exceed said deviation range (DR) by: for at least two different deviation pairs (k), each comprising a first and a second deviation (D1k(t1k), D2k(t2k)) determined based on the filtered deviations (FD(ti)), determining a simulated value (SRTk) of the remaining time (RT) by performing a Monte Carlo simulation based on the noise (N) and the respective deviation pair (k), based on the simulated values (SRTk) determining the remaining time (RT), and generating an output informing about the remaining time (RT).