Patent ID: 11913976
Assignee: ENDRESS+HAUSER WETZER GMBH+CO. KG
Field: Measurement (Instruments)
Classification: CPC G | IPC G

Claim 7:
8. A method for transmitting a measured process variable of a field device, comprising:
providing the field device, including:
a sensor designed to measure the process variable;
an interface having at least four electrical contacts;
a first electrical current regulator designed to set a first electrical current between a first contact of the at least four electrical contacts and a second contact of the at least four electrical contacts when the field device is contacted via the interface such that a first voltage source is connected across the first and the second contacts;
a second electrical current regulator designed to set a second electrical current between the first contact and a third contact of the at least four electrical contacts when the field device is contacted via the interface such that a second electrical voltage source is connected across the first and the third contacts and to generate a second signal; and
a control unit designed to:
transmit the measured process variable according to a predefined digital standard via a fourth contact of the at least four electrical contacts when the second electrical current is settable between the first contact and the third contact, and
control the first electrical current regulator such that the electrical current level of the first electrical current corresponds to the measured process variable according to a predefined electrical current signal standard when the second electrical current regulator generates the second signal;

measuring the process variable,
setting the second electrical current between the first contact and the third contact when the field device is contacted via the interface such that the second electrical voltage source is connected across such contacts, and otherwise generating the second signal;
transmitting the measured process variable according to the predefined digital protocol via the fourth contact when the second signal is not generated;
setting the first electrical current between the first contact and the second contact when the field device is contacted via the interface such that the first electrical voltage source is connected across such contacts, and otherwise generating the first signal;
wherein method steps are cyclically repeated when the first signal is not generated, and
wherein, when the first signal is generated, measuring the process variable, transmitting the measured process variable according to the predefined digital protocol via the fourth contact, setting the first electrical current, and generating of the first signal are repeated.