A measuring-device system, comprising:
- a first measuring device embodied as a two-conductor field device,
- having a first measured variable transducer which is adapted to react to a first measured variable and to provide a first transducer signal, including an electrical, first transducer signal such that the first transducer signal follows a change of the first measured variable with a change of at least one signal parameter, and
- having, electrically connected with the first measured variable transducer, and formed by means of at least one microprocessor, a first measurement transmitter which has an interface circuit serving both for wired energy supply as well as also for wired signal transmission and which is adapted to receive the first transducer signal and to convert such into an electrical output signal of the interface circuit representing the first measured variable and embodied as a binary coded, switching signal;
- a second measuring device,
- having a second measured variable transducer which is adapted to react to a second measured variable and to provide a second transducer signal, including an electrical, second transducer signal such that the second transducer signal follows a change of the second measured variable with a change of at least one signal parameter, and
- having, electrically connected with the second measured variable transducer, and formed by means of at least one microprocessor, a second measurement transmitter which has an interface circuit for wired energy supply and a radio unit and which is adapted to receive the second transducer signal and to convert such into a radio signal transmitted via the radio unit and wirelessly transmitting a sequence of measured values quantifying the second measured variable;
- and
- an evaluating and supply electronics,
- wherein the interface circuit of the first measurement transmitter is electrically connected to the evaluating and supply electronics to form an electrical current loop involving both the interface circuit of the first measurement transmitter and the evaluating and supply electronics,
- wherein the interface circuit of the second measurement transmitter is electrically connected to the first measurement transmitter and/or the electrical current loop formed therewith,
- wherein the evaluating and supply electronics is adapted to supply electrical power into the electrical current loop,
- wherein the first measurement transmitter is adapted both to draw electrical power from the electrical current loop as well as also to transmit a measurement signal to the evaluating and supply electronics by modulation of an electrical current in the electrical current loop driven by the evaluating and supply electronics,
- wherein the first measure device is adapted to operate at times in a first operating mode in which the first measurement transmitter delivers the measurement signal with a signal level which is greater than a predetermined minimum value,
- wherein the first measuring device is adapted at times to operate not in its first operating mode and during that to operate at least at times in a second operating mode of the first measurement device in which the first measurement transmitter delivers the measurement signal with a signal level which is less than said predetermined value,
- wherein the second measurement transmitter is adapted to draw electrical power from the electrical current loop and to control the second measuring transducer and/or the radio unit as a function of an instantaneous electrical current level of an electrical current in the electrical current loop,
- wherein the second measuring device is adapted at times to operate in a first operating mode of the second measuring device in which the second measuring transducer provides the second transducer signal and in which the second measurement transmitter receives the second transducer signal and converts such at least in to the radio signal,
- wherein the second measuring device is adapted at times not to operate in its first operating mode and during that to operate at least at times in a second operating mode of the second measuring device in which the second measuring transducer does not provide the second transducer signal and/or in which the second measurement transducer does not convert the second transducer signal into the radio signal,
- wherein the second measuring device is adapted to operate in its first operating mode if the first measuring device operates in its first operating mode, and
- wherein the second measuring device is adapted to operate in its second operating mode if the first measuring device operates in its second operating mode.