Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.