Patent ID: 8442782
Filing Date: 2013-05-14
Classification: G01F,G01N

Abstract:
1. A method for determining and/or monitoring at least one process variable of a medium, wherein: at least one mechanically oscillatable unit is supplied with an exciter signal, at least one received signal coming from the mechanically oscillatable unit is received and evaluated in reference to at least one process variable to be determined and/or monitored, and the exciter signal is produced such that a phase difference between the exciter signal and said at least one received signal is essentially equal to a predeterminable phase value, the method comprising the steps of: establishing at least one criterion for judging the determining of the phase difference between the exciter signal and the said at least one received signal, or signals dependent on the exciter signal or on said at least one received signal; in a case, in which said at least one criterion for judging the determining of the phase difference is fulfilled, tuning of the phase difference is closed-loop controlled; and in a case, which is alternative to the case where said at least one criterion for judging the determining of the phase difference is fulfilled, tuning of the phase difference is open-loop controlled.