Siemens Aktiengesellschaft

Patrick Balle

Eric Chemisky

Stefan Gross

A field device for process instrumentation, i.e., a measuring transducer, actuator, or mobile operating device, which is suitable for use in explosion-prone areas. The field device is battery-driven and has at least one battery for supplying an electronic unit with energy. A battery compartment is constructed such that standard batteries can be inserted without the risk of spark formation. A corresponding design of a supply circuit ensures that the circuit can only be closed, for example, when closing the battery compartment once a lid is closed to the extent that the battery compartment meets the requirements for use in explosion-prone areas. The invention has the advantage that comparatively inexpensive standard batteries can be used and that the ignition protection is maintained during the entire battery switching process.

Field device for process instrumentation

A circuit arrangement for detecting and digitizing an analog input signal and to a field device for process instrumentation, wherein the field device comprises such a circuit arrangement which includes a first electronics unit, a second electronics unit, and an interface by which the two electronics units are galvanically separated from each other. A first signal is generated at a first frequency in the second electronics unit. A voltage frequency converter, to which the analog input signal is routed, uses a reference frequency to generate a second signal at a second frequency that corresponds to the level of the analog input signal. After the second signal has been transmitted to the second electronics unit using an optical coupler, a ratiometric measurement of the second frequency is performed in the second electronics unit dependent on the first frequency using a capture timer.

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Malsch, Germany

Patrick Balle