serial interface

Abstract

An electronic unit comprising a microcontroller (μC) having a control input (μC_sw), at least one control output (μC_ctl1) and a signal input (μC_rx), and an interface circuit (IF) having at least one connection terminal (IF_ext1), a control output (IF_ctl), a control input (IF_sw1) and a signal output (IF_tx). The control output (IF_ctl) is electrically connected to the control input (μC_sw), the control output (μC_ctl1) is electrically connected to the control input (IF_sw1), and the signal output (IF_tx) is electrically connected to the signal input (μC_rx). Both the microcontroller and the interface circuit have a respective first operating mode (μC I ; IF I ) and at least one respective second operating mode (μC II ; IF II ). The microcontroller is designed to output an instruction at the control output (μC_ctl) in the operating mode (μC I ) which causes the interface circuit to operate in the first operating mode, and the interface circuit is designed to differentiate an input signal (e1) applied at the connection terminal (IF_ext1), that is to say to convert the input signal into a differentiated signal (a1) which represents the differential of the input signal over time, and to generate a binary control signal using the differentiated signal (a1) and to output the binary control signal at the control output (IF_ctl) at least in the first operating mode (IF I ). The microcontroller is additionally designed to output an instruction at the control output (μC_ctl1) in the operating mode (μCII) which causes the interface circuit (IF) to operate in the operating mode (IF II ), and the interface circuit is designed to convert a digital input signal applied at the connection terminal (IF_ext1) into a binary output signal (sD1) which represents the digital input signal in the operating mode (IF II ), and to output the output signal at the signal output (IF_tx). The microcontroller (μC) is additionally designed to receive and process a digital input signal applied at the signal input (μC_rx) in the operating mode (μC II ).

Description

Technical Field

[0001] The present invention relates to an electronic unit having a microcontroller and an interface circuit electrically connected to the microcontroller. Background Technology

[0002] US-A2008 / 015799, US-A2010 / 0026518, or US-A2011 / 0208440 respectively disclose an electronic unit, particularly for one or more measuring devices, and a measuring system having such an electronic unit and one or more sensors connected to the electronic unit.

[0003] The electronic unit—designed here as a transducer in a measurement system for industrial measurement and automation technologies—transmits measurement data to a remote signal receiver—including a microprocessor or a microcontroller formed from a microprocessor—and also includes interface circuitry electrically connected to the microprocessor or microcontroller, i.e., electronic circuitry for communicating with external signal receivers and / or transmitters. This communication can be non-proprietary or standardized. To provide the electrical power required during operation, and in some cases utilizing different operating voltages, the electronic unit also has corresponding power supply circuitry. The power supply circuitry, or the power supply circuitry formed from it, can be, for example, AC-powered and / or battery-powered. Therefore, the electronic unit can be electrically connected to an external power source—which itself is also AC-powered and / or battery-powered—for example, by means of a 4mA to 20mA current loop or a serial fieldbus formed by a 2-wire line, and / or the electronic unit can be equipped with internal, and in some cases, rechargeable, electrochemical energy storage.

[0004] The interface circuit of the aforementioned electronic unit, in each case, has connection terminals for connecting to external lines and signal input terminals electrically connected to the signal output terminals of the microcontroller. This interface circuit is designed to convert digital signals applied to the signal input terminals during operation of the electronic unit into digital signals conforming to, for example, the EIA-485 standard (RS-485) at the connection terminals. Furthermore, the electronic unit shown in US-A2008 / 015799 is also specifically designed to receive and process digital signals output from an external transducer and arriving at the connection terminals of the interface circuit, i.e., to execute one or more instructions contained in the signals in the microcontroller. In the electronic unit shown in US-A2008 / 015799, signal transmission between the interface circuit and the microcontroller is performed, for example, through optocouplers with current isolation.

[0005] To enable the transmission and reception of digital signals at the same connection terminal, the interface circuit can also be designed to operate in a so-called alternating mode (half-duplex). In a receive-ready operating mode, the interface circuit receives digital input signals applied at the connection terminal and forwards transducer instructions to the microcontroller, converting the signals into binary output signals representing the digital input signals and outputting the output signals to the microcontroller. In different transmit-ready operating modes, the interface circuit receives digital output signals from the microcontroller, converts these signals into binary output signals representing the digital output signals for the electronic unit, and outputs the output signals to the connection terminal or to the signal lines connected to the connection terminal. When the two-wire line is also used for transmitting and receiving data, data transmission can be controlled non-cyclically using a data flow control method (handshake). For example, if there is no request from a higher-level data processing unit connected to the two-wire line that needs to be answered, the interface circuit is allowed to operate in the receive-ready operating mode accordingly.

[0006] Therefore, the interface circuit must be continuously operational to ensure reliable and error-free data transmission; this is especially true even when no data is transmitted between higher-level data processing units and electronic units. This is particularly problematic in the case where electronic units are powered solely by internal energy storage and / or via a two-wire line—that is, at low power levels of less than 100mW (≤4mA·25V)—significantly limiting implementation; this is even more true for the aforementioned case of signal transmission via current isolation points set in the interface circuit, thus further increasing the nominal power requirement. Summary of the Invention

[0007] Based on the above-mentioned prior art, the object of the present invention is to improve the electronic unit of the type discussed so that the corresponding interface of the electronic unit has a low rated power when establishing a receive-ready operating mode, and in particular, the rated power of the interface is low enough to be used in electronic units that are at least sometimes supplied with less than 100mW of electrical power.

[0008] To achieve this objective, the present invention includes an electronic unit designed as, for example, a communication interface or as remote I / O of a measurement system and / or powered by a battery, the electronic unit comprising:

[0009] • A microcontroller having a control input, at least one first control output, and a signal input, which is designed, for example, an asynchronous serial interface (UART) or a switch input;

[0010] • And an interface circuit having at least one first connection terminal, a control output terminal, a first control input terminal, and a signal output terminal.

[0011] In the electronic unit according to the present invention

[0012] The control output of the interface circuit is electrically connected to the control input of the microcontroller.

[0013] The first control output of the microcontroller is electrically connected to the first control input of the interface circuit.

[0014] Furthermore, the signal output terminal of the interface circuit is electrically connected to the signal input terminal of the microcontroller.

[0015] Both the microcontroller and the interface circuit have a first operating mode and at least one second operating mode. The microcontroller is designed to output a command at a first control output terminal in its first operating mode, causing the interface circuit to operate in its first operating mode. The interface circuit is designed to differentiate the input signal applied at the first connection terminal, at least in its first operating mode; that is, the interface circuit is designed to convert the input signal into a differential signal representing the differential of the input signal over time. The interface circuit is also designed to generate a binary control signal and output the binary control signal at the control output terminal by means of the differential signal. Furthermore, the microcontroller is designed to output a command at the first control output terminal in its second operating mode, causing the interface circuit to operate in its second operating mode. The interface circuit is designed to convert a digital input signal applied at the first connection terminal, conforming to, for example, IEC 61158CPF15:2007 and / or EIA-485, into a binary first output signal representing the digital input signal in its second operating mode, and output the first output signal at the signal output terminal. In addition, the microcontroller is designed to receive and process, for example, UART-compliant digital input signals applied at the signal input in its second operating mode, that is, to execute, for example, instructions contained in the input signals and / or evaluate messages contained in the input signals.

[0016] Furthermore, the invention also includes a communication system formed by means of such an electronic unit, the unit further including a transducer electrically connected to the electronic unit, the transducer being designed to transmit digital signals to the electronic unit, particularly digital signals conforming to IEC 61158CPF15:2007; and / or the invention also includes a measurement system formed by means of such an electronic unit and includes a sensor electrically coupled to the electronic unit, wherein the microcontroller is designed to receive and evaluate, for example, sensor signals generated by means of the sensor, at least in its first operating mode, to determine a measurement value of at least one measured variable detected by means of the sensor.

[0017] According to a first embodiment of the invention, the interface circuit is further provided to respond to changes in the digital input signal, namely, changes in the logic level of the input signal and / or changes in the signal edge with an edge steepness greater than 1V / μs when the instruction (IRQ) is encoded as a control signal, the control signal causing the microcontroller to operate in its second operating mode or to switch the microcontroller from its first operating mode to its second operating mode.

[0018] According to a second embodiment of the invention, the microcontroller is further provided to process control signals applied at the control input of the interface circuit in its first operating mode, that is, to respond to, for example, instructions that switch from the first operating mode to the second operating mode by switching to the second operating mode.

[0019] According to a third embodiment of the present invention, the interface circuit is further provided to be designed so that, in a first operating mode, neither the digital input signal applied at the first connection terminal is converted into an output signal representing the input signal, nor is an output signal representing the digital input signal applied at the first connection terminal at the signal output terminal is output.

[0020] According to a fourth embodiment of the invention, the microcontroller is further provided to not process the digital input signal applied at the signal input terminal in a first operating mode, nor, for example, execute the instructions contained in the digital input signal.

[0021] According to a fifth embodiment of the invention, a further provision is provided that, for example, when no digital and / or UART-compatible input signal is present at the signal input terminal, the microcontroller is designed to switch from a second operating mode to a first operating mode in a time-controlled manner.

[0022] According to a sixth embodiment of the present invention, the interface circuit and the microcontroller are further provided to operate simultaneously in a corresponding second operating mode, such that a first output signal at the signal output terminal of the interface circuit forms a digital input signal applied at the signal input terminal of the microcontroller, and the microcontroller receives and processes the first output signal.

[0023] According to a seventh embodiment of the present invention, the interface circuit is further provided to have, for example, a passive signal filter, such as a high-pass filter.

[0024] According to an eighth embodiment of the present invention, the interface circuit for differentiating the input signal applied at the first connection terminal has a high-pass filter, such as a passive filter and / or a filter having a cutoff frequency greater than 800 Hz.

[0025] In a ninth embodiment of the invention, it is further provided that the interface circuit is designed to obtain the electrical power required during operation from the input signal applied at the first connection terminal at least temporarily and / or at least partially, for example, to obtain the electrical power required, i.e., the power required in the first operating mode, solely from the input signal applied at the first connection terminal.

[0026] In the tenth embodiment of the present invention, it is further provided that the power requirement of the interface circuit in the first operating mode is less than 50mW.

[0027] According to the eleventh embodiment of the present invention, the power requirement of the interface circuit in the second operating mode is higher than that of the interface circuit in the first operating mode, for example, greater than 300% of the power requirement of the interface circuit in the first operating mode, and / or greater than 150mW.

[0028] According to a twelfth embodiment of the invention, the interface circuit is further designed to obtain the required electrical power solely from the input signal applied at the first connection terminal in both the first operating mode and the second operating mode.

[0029] According to a first improvement of the invention, the microcontroller has a signal output terminal designed, for example, as an asynchronous serial interface (UART), and the interface circuit has a signal input terminal designed, for example, as an asynchronous serial interface (UART), and the signal output terminal of the microcontroller is electrically connected to the signal input terminal of the interface.

[0030] According to a first embodiment of the first improvement, both the microcontroller and the interface circuit each have at least a third operating mode, such that the microcontroller is designed to output a second digital output signal conforming to, for example, UART and applied at a signal output terminal in its third operating mode, and the interface circuit is designed to convert a digital input signal conforming to, for example, UART and applied at a signal input terminal into a third digital output signal conforming to, for example, IEC 61158CPF15:2007 and / or EIA-485 in its third operating mode. The interface circuit can also be designed to output a third output signal at a first connection terminal in the third operating mode. Alternatively, the interface circuit may have a second connection terminal, and the interface circuit may also be designed to output a third output signal at the second connection terminal in the third operating mode, and, for example, not convert the input signal applied at the signal input terminal into an output signal representing the input signal in the first operating mode and the second operating mode, nor output an output signal representing the input signal applied at the signal input terminal at the second connection terminal.

[0031] According to a second embodiment of the first improved solution, the microcontroller has a second control output terminal, and the interface circuit has a second control input terminal, and the second control output terminal of the microcontroller is electrically connected to the second control input terminal of the interface circuit. Furthermore, the microcontroller can also be designed to output instructions at the second control output terminal, causing the interface circuit to operate in its third operating mode, in a third operating mode.

[0032] According to a third embodiment of the first improvement, the microcontroller is further designed to switch from a second operating mode to a third operating mode by being controlled by an input signal at the signal input terminal.

[0033] According to a fourth embodiment of the first improvement, the microcontroller is further designed to automatically switch from a third operating mode to a first operating mode after outputting a digital output signal at the signal output terminal.

[0034] According to a fifth embodiment of the first improvement, the microcontroller is further designed to not process the digital input signal applied at the signal input terminal in the third operating mode, that is, for example, not to execute any instructions arriving at the signal input terminal.

[0035] According to the sixth embodiment of the first improved solution, the interface circuit is further designed to not convert the input signal applied at the signal input terminal into an output signal representing the input signal in the first operating mode and the second operating mode, nor to output an output signal representing the input signal applied at the signal input terminal at the first connection terminal.

[0036] According to the seventh embodiment of the first improvement, the interface circuit and the microcontroller are further designed to operate simultaneously in a corresponding third operating mode, such that the second output signal at the signal output terminal of the microcontroller forms a digital input signal applied at the signal input terminal of the interface circuit, and the interface circuit receives and processes the second output signal, that is, converts the second output signal into, for example, a third output signal.

[0037] According to the eighth embodiment of the first improvement, the interface circuit further includes a transceiver (RS485), such as a transceiver compatible with IEC 61158CPF15:2007 and / or EIA-485, and / or a monolithic transceiver, such as the SN65HVD1781 transceiver from Texas Instruments in 2019 or the THVD2450 transceiver from Texas Instruments in 2019, and the first connection terminal of the interface circuit is formed by means of at least one of the bus driver / receiver terminals of the transceiver, the signal output terminal of the interface circuit is formed by means of the digital output terminal of the transceiver, and the signal input terminal of the interface circuit is formed by means of the digital input terminal of the transceiver.

[0038] According to a second improvement of the invention, the electronic unit further includes a power supply circuit formed, for example, by means of electrochemical and / or rechargeable energy storage, and further provided that the power supply circuit has at least one first power supply terminal and is designed to provide an operating voltage to the microcontroller at the first power supply terminal, and the power supply terminal of the microcontroller is electrically connected to the first power supply terminal of the power supply circuit.

[0039] According to the first embodiment of the second improvement, the power supply circuit has a second power supply terminal and is designed to provide an operating voltage for the interface circuit at the second power supply terminal, and the power supply terminal of the interface circuit is electrically connected to the second power supply terminal of the power supply circuit.

[0040] According to the first embodiment of the second improvement, the interface circuit further includes an electronic main switch formed, for example, by means of a semiconductor relay or by means of an insulated gate field-effect transistor, wherein both the first control input terminal and the power supply terminal of the interface circuit are formed by means of the main switch.

[0041] According to a third improvement of the invention, the interface circuit has, for example, a current-isolated DC / DC voltage converter having a converter input and a converter output, such as a flyback converter or a push-pull converter, and the DC / DC voltage converter is designed to convert an input DC voltage applied at the converter input into an output DC voltage applied at the converter output, and the voltage level is different from the voltage level of the input DC voltage.

[0042] According to a fourth improvement of the present invention, the interface circuit includes a first optical coupler having an optical emitting element and an optical receiving element, and further provided that the control output terminal of the interface circuit is formed by means of the first optical coupler, such that the optical receiving element of the first optical coupler is electrically connected to the control input terminal of the microcontroller.

[0043] According to an embodiment of the fourth improvement of the present invention, the interface circuit further includes a second optical coupler having an optical emitting element and an optical receiving element. Furthermore, the signal output terminal of the interface circuit is formed by means of the second optical coupler, such that the optical receiving element of the second optical coupler is electrically connected to the signal input terminal of the microcontroller. Additionally, the interface circuit may also have at least a third optical coupler having an optical emitting element and an optical receiving element, or for example, a third optical coupler having an optical emitting element and an optical receiving element, and at least a fourth optical coupler, which in each case has an optical emitting element and an optical receiving element, wherein, for example, the first control input terminal of the interface circuit may be formed by means of the third optical coupler, such that the optical receiving element of the third optical coupler is electrically connected to the first control output terminal of the microcontroller.

[0044] The basic concept of this invention is to enable the interface circuit of an electronic unit, controlled by its microcontroller, to operate selectively in a first operating mode, or, if necessary, at the request of an external transducer electrically connected to the interface circuit, in a second operating mode, such that in the first operating mode a receive-ready state is established, which evaluates passive signals, i.e., any signals arriving at the connection terminal, only with respect to at least one of its physical signal parameters or their temporary progress, and a receive-ready state is established in the second operating mode, which forwards active signals, i.e., any digital input signals arriving at the connection terminal, to the microcontroller, in some cases, the microcontroller also correspondingly converts the input signals for this purpose, particularly such that, in its second operating mode (up to the second operating mode), the interface circuit sends messages contained in the microcontroller's input signals, such as instructions in a form that can be evaluated by the microcontroller. As a result of this functional division of the interface circuit with respect to its receive-ready state relative to the digital input signals received occasionally or aperiodically at the connection terminals, the energy requirements of the interface circuit can be reduced to a considerable extent by allowing the interface circuit to operate only as needed, that is, only after a digital input signal is input in the relatively energy-intensive second operating mode; advantageously, it also makes it possible to reduce the electrical power fed in by the external transducer as a whole when the electronic unit is running. Attached Figure Description

[0045] The invention and its advantageous embodiments are explained in more detail below with reference to the exemplary embodiments shown in the accompanying drawings. In all the drawings, parts with the same or equivalent function or purpose have the same reference numerals; the aforementioned reference numerals are omitted in subsequent figures for clear reasons or if it seems reasonable for other reasons. Further advantageous embodiments or improvements, especially combinations of parts of the invention initially explained separately, are also derived from the drawings and / or from the claims themselves.

[0046] The diagram shows in detail:

[0047] Figure 1 The electronic unit according to the present invention is schematically shown in the form of a block diagram;

[0048] Figure 2 The diagram schematically illustrates the following based on... Figure 1 The deformation of the electronic units;

[0049] Figure 3 The diagram schematically illustrates the following based on... Figure 1 Another variation of the electronic unit;

[0050] Figure 4 The diagram schematically illustrates what is suitable for... Figure 1 , Figure 2 or Figure 3 The interface circuit of the electronic unit; and

[0051] Figure 5 , Figure 6 , Figure 7 Each of them schematically illustrates, in the form of a block diagram, what is suitable for... Figure 1 , Figure 2 or Figure 3 Different components of the interface circuit of the electronic unit. Detailed Implementation

[0052] Figure 1 , Figure 2 and Figure 3 Various exemplary embodiments of an electronic unit formed by means of a microcontroller μC and an interface circuit IF connected thereto are schematically shown. For example... Figure 1 , Figure 2 and Figure 3As shown, the electronic unit can be, for example, a component of an additional communication system electrically connected to the electronic unit and, in some cases, also having a transducer NLU disposed remotely from the electronic unit. The transducer NLU can be, for example, a remote controller (remote I / O), a programmable logic controller (PLC), or a bus master in a fieldbus that conforms to industry standard IEC 61158:1999, particularly to one of the CPF1 (FOUNDATION FIELDBUS), CPF3 (PROFIBUS), CPF9 (HART), or CPF15 (MODBUS) series; or it can be, for example, a radio module or radio adapter conforming to IEEE 802.15.4:2007 (Wireless HART), wherein the transducer NLU can be AC-powered and / or battery-powered. Alternatively or additionally, the electronic unit may also be a component of a measurement system, such as a component of a measuring and / or switching device in an industrial measurement and automation system, having a sensor MA, such as a flow sensor, electrically coupled to the electronic unit. This electronic unit is further designed to capture at least one physical or chemical analyte and supply at least one measurement signal s1 representing said analyte, particularly for processing within the electronic unit. The electronic unit may also be designed to receive said measurement signal s1 and process said measurement signal s1 accordingly, for example, to determine a measurement value, which in some cases is digital and quantifies at least one analyte. Furthermore, as... Figure 1 and Figure 2 The electronic unit shown can be arranged inside a protective housing H, which can also be directly attached to the aforementioned sensor MA, thus forming a compact measuring device.

[0053] As from Figure 1 , Figure 2 or Figure 3As can be seen from the combination thereof, the interface circuit IF has at least one first connection terminal IF_ext1, a control output terminal IF_ctl, a first control input terminal IF_sw1, and a signal output terminal IF_tx. Furthermore, the microcontroller μC has a control input terminal μC_sw, at least one first control output terminal μC_ctl1, and at least one signal input terminal μC_rx. The control input terminal μC_sw of the microcontroller μC can, for example, be an interrupt input terminal typically provided for conventional microprocessors or microcontrollers, or, in the event of at least a temporary interruption of the initial program execution or at least a temporary interruption of the execution of a corresponding predetermined interrupt routine (ISR - Interrupt Service Routine, interrupt handler), the microcontroller μC can be designed to respond, for example, in the form of a single bit such as logic 1, to (control) instructions (IRQ – interrupt request) arriving at the control input terminal μC_sw. Alternatively or additionally, the signal input terminal μC_rx can, for example, be designed as a simple switch input terminal, or can also be designed, for example, as an asynchronous serial interface (UART - Universal Asynchronous Receiver Transmitter), or can be implemented by means of a corresponding function block of the microcontroller μC. Figure 1 , Figure 2 and Figure 3 As illustrated, the control output terminal IF_ctl of the interface circuit IF is electrically connected to the control input terminal μC_sw of the microcontroller μC, the signal output terminal IF_tx of the interface circuit IF is electrically connected to the signal input terminal μC_rx of the microcontroller μC, and the control output terminal μC_ctl1 of the microcontroller μC is electrically connected to the control input terminal IF_sw1 of the interface circuit IF. Furthermore, the connection terminal IF_ext1 of the interface circuit IF is designed to be electrically connected to an external signal line 2L, for example, so that the interface circuit IF or the electronic unit formed by the interface circuit IF is connected to the corresponding connection terminal of the transducer NLU via the signal line 2L. In addition, the electronic unit is further designed to receive the binary input signal e1 via the connection terminal IF_ext1 of the interface circuit IF, and, if necessary, process or evaluate the binary input signal e1 accordingly by means of the interface circuit IF and the microcontroller μC. The input signal e1 can be, for example, a binary (switching) signal that transmits a simple switching command from the transducer NLU, or it can be, for example, a digital signal that transmits, for example, a telegram issued by the transducer NLU and also conforms to the industry standard IEC 61158CPF15:2007.

[0054] According to another embodiment of the invention, the microcontroller μC further includes a signal output terminal μC_tx, which is also designed as, for example, an asynchronous serial interface, and the interface circuit IF has a signal input terminal IF_rx, similar to the aforementioned signal output terminal μC_tx, which is designed as an asynchronous serial interface. Figure 2As shown, the signal output terminal μC_tx of the microcontroller and the signal input terminal IF_rx of the interface IF are also electrically connected to each other.

[0055] In the electronic unit according to the invention, the microcontroller μC and the interface circuit IF each have, in each case: a first operating mode, namely operating mode μC. I Or run mode IF I ; and at least a second operating mode, namely operating mode μC. II Or run mode IF II .

[0056] The μC microcontroller is specifically designed for use in its first operating mode, μC. I The following command is output at the control output terminal μC_ctl1, which causes the interface circuit to operate in its IF mode. I Run it, for example, switch to run mode IF. I Or activate the IF running mode I The aforementioned instructions can be, for example, simple switching commands, or statements to be executed in the program processed by the interface circuit IF. Furthermore, the microcontroller μC is also designed to operate in its second operating mode, μC. II The following command is output at the control output terminal μC_ctl1, which causes the interface circuit IF to operate in its second mode IF. II The microcontroller μC operates in a manner that allows it to receive and process, for example, UART-compliant digital input signals applied at its signal input terminal μC_rx, specifically such that instructions contained in the input signals applied at the aforementioned signal input terminal μC_rx, such as simple switching commands or statements affecting the program running in the microcontroller μC, are executed by the microcontroller μC, and / or messages contained in the input signals are evaluated by the microcontroller μC. In the case where the electronic unit is a component of the measurement system, the microcontroller μC may also be designed to operate at least in its first operating mode μC. I However, for example, it is also running in μC mode. I and running mode μC II Both receive and evaluate the aforementioned sensor signal s1 generated by means of sensor MA, for example, to determine the measurement value of at least one measured variable captured by means of sensor MA.

[0057] In the electronic unit according to the present invention, the interface circuit IF is designed to be at least in the first operating mode IF I The following is a differentiating step on the input signal e1 applied to the connection terminal IF_ext1 of the interface circuit, that is, as follows: Figure 4As shown, the input signal e1 is converted into a differential signal a1, which represents the derivative of the input signal e1 over time. A binary control signal is generated using the differential signal a1, and this binary control signal is output at the control output terminal IF_ctl. Specifically, this ensures that the interface circuit IF operates at least in the first operating mode IF. I The following is an example of only running in the first IF mode. I The microcontroller μC responds to a predetermined rate of change of the input signal e1 by encoding the instruction IRQ into a control signal IF_ctl, which enables it to operate in its second mode μC. II This allows the microcontroller μC to run in either of its first operating modes, or it causes the μC to switch from its first operating mode. I Switch to its second running mode μC II .like Figure 4 It also indicates that if the logic level of the binary input signal e1 changes, for example from logic 0 to logic 1, the differential signal a1 can have a pulse-shaped level distribution corresponding to this change. That is, when there is a sudden change, the differential signal a1 can have a needle-like level distribution, such that the differential signal a1 temporarily reaches or exceeds the minimum signal level encoded for the aforementioned instruction IRQ. Furthermore, the microcontroller according to another embodiment of the invention is accordingly designed to operate in mode μC. I The next step is to process the control signal of the interface circuit IF applied at the control input terminal μC_sw, that is, to respond to, for example, the aforementioned instruction IRQ, which causes the switch to the operating mode μC accordingly. II From running mode μC I Switch to run mode μC II .

[0058] According to another embodiment of the invention, the interface circuit IF is specifically designed to encode the aforementioned instruction IRQ into a control signal at the control output terminal IF_ctl, or if the rate of change of the input signal e1 corresponds to a signal edge with an edge steepness greater than 1V / μs and / or a rate of change greater than 90% / μs of a logic level that is nominally achievable under normalization and / or if the rate of change of the input signal e1 corresponds to a logic level of a digital input signal conforming to industry standards IEC 61158 CPF15:2007 (MODBUS) and / or EIA-485, then the control signal is output at the control output terminal IF_ctl at a corresponding signal level, at least temporarily. According to another embodiment of the invention, the interface circuit IF is also designed to directly output the differential signal a1 at the control output terminal IF_ctl as a control signal. To differentiate the input signal e1 or to generate the differential signal a1, the interface circuit may, for example, have a corresponding signal filter, such as a first-order high-pass filter or possibly a higher-order high-pass filter. The (lower) cutoff frequency of this high-pass filter can be set, for example, above 800Hz, especially when using digital input signals conforming to industry standards IEC61158CPF15:2007 and / or EIA-485. Furthermore, the interface circuit IF of the electronic unit according to the invention is also designed in its second operating mode IF II The digital input signal (e.g., the aforementioned input signal e1) conforming to, for example, IEC 61158CPF15:2007 and / or EIA-485, applied to the connection terminal IF_ext1, is converted into a binary first output signal sD1 representing the input signal, and the output signal sD1 is output at the signal output terminal IF_tx, such that the output signal sD1 is applied to the signal input terminal μC_rx of the microcontroller μC or forms the aforementioned input signal at the signal input terminal μC_rx of the microcontroller μC. Therefore, according to another embodiment of the invention, the interface circuit IF and the microcontroller μC are also designed to at least temporarily operate simultaneously in the corresponding second operating mode IF. II or μC II In operation, specifically, the output signal at the signal output terminal IF_tx of the interface circuit IF is formed as a digital input signal applied at the signal input terminal μC_rx of the microcontroller μC, and the microcontroller μC receives and processes the first output signal. According to another embodiment of the invention, the interface circuit is also designed so that in its operating mode IF... I The following prevents the application of digital input signals at the IF_ext1 connection terminal, meaning it does not convert the output signal into a signal representing the input signal, nor does it output any output signal representing the digital input signal applied at the IF_tx signal output terminal, and / or the microcontroller μC is designed to prevent such applications from being applied at the IF_ext1 connection terminal.I This prevents digital input signals from being applied to the signal input terminal μC_rx, meaning that the instructions contained in the digital input signals are not processed, and in particular, are not executed. Furthermore, especially in the absence of digital input signals and / or no UART-compliant input signals being applied to the signal input terminal μC_rx, the microcontroller μC can also be advantageously designed to exit its operating mode μC in a time-controlled manner. II Switch to its running mode μC I .

[0059] In the aforementioned case where the microcontroller μC has a signal output terminal μC_tx and the interface circuit IF has a signal input terminal IF_rx electrically connected to the signal output terminal μC_tx, according to another embodiment of the present invention, both the microcontroller μC and the interface circuit IF further have at least a third operating mode, namely operating mode μC. III μC or operating mode IF III .like Figure 3 As shown, the microcontroller μC is also designed to operate in μC mode. III The second digital output signal sD2 is output at the signal output terminal μC_tx. Furthermore, the interface circuit IF is designed to operate in IF mode. III The digital input signal applied to the signal input terminal IF_rx is then converted into a third digital output signal sD3. Specifically, the interface circuit IF and the microcontroller μC are further designed to operate, at least temporarily, simultaneously in their respective third operating modes μC. III or IF III Under the following conditions, the output signal sD2 at the signal output terminal μC_tx forms a digital input signal applied at the signal input terminal IF_rx, and the interface circuit IF receives and processes the output signal sD2, for example, converting the output signal sD2 into an output signal sD3. The output signal sD2 can be, for example, a digital signal conforming to UART. Alternatively or additionally, the output signal sD3 can be a digital signal conforming to any of the aforementioned industry standards IEC 61158 CPF15:2007 and / or EIA-485. In the above-described case where the electronic unit is a component of the measurement system, the microcontroller μC can be particularly designed in its operating mode μC III The measured value of at least one measured variable captured by the sensor MA is transmitted to the interface circuit IF via the output signal sD2, or the interface circuit IF may also be designed to output the measured value received with the output signal sD2 via the output signal sD3.

[0060] Especially for the aforementioned transducer NLU, which is designed to both transmit the input signal e1 and receive the output signal sD3 via signal line 2L and process the input and output signals accordingly, a communication system is thus established to exchange data between the electronic unit and the transducer NLU in an alternating mode (half-duplex), and the interface circuit is further designed for its operating mode IF. III The output signal sD3 is then output at the IF_ext1 terminal. Alternatively, as follows... Figure 2 As indicated, the interface circuit IF may further have a second connection terminal IF_ext2, and the interface circuit IF may also be designed to be used in its operating mode IF III The aforementioned output signal sD3 is output at the connection terminal IF_ext2, for example, to enable data exchange with the transducer NLU in full-duplex transmission. In this case, the interface circuit IF can also be further designed accordingly to not only be in the first operating mode IF I Furthermore, in the second running mode IF II The following prevents any input signal applied at the signal input terminal IF_rx, that is, it does not convert the input signal into an output signal representing the input signal, nor does it output any output signal representing the input signal applied at the above-mentioned connection terminal IF_ext2.

[0061] According to another embodiment of the invention, the microcontroller μC is further designed to operate from a second operating mode μC in a manner controlled by, for example, by means of the output signal sD2, from the input signal sD1 at the signal input terminal μC_rx. II Switch to the third running mode μC III For example, to confirm the execution of instructions encoded in input signal sD1 and / or accordingly respond to requests explicitly contained in or at least implicitly transmitted with input signal sD1. Alternatively or further, the microcontroller μC can also be designed to automatically switch from operating mode μC after the digital output signal sD2 is output at signal output terminal μC_tx. III Switch back to running mode μC I Advantageously, the interface circuit IF can also operate in its IF mode. I and its operating mode IF II Both are designed to prevent any input signal applied to the signal input terminal IF_rx, that is, not to convert the input signal into an output signal representing the input signal, nor to output any output signal representing the input signal applied to the signal input terminal IF_rx at the connection terminal IF_ext1, and / or the microcontroller μC can be designed to operate in μC mode. IIIIt does not process any digital input signals applied at the signal input terminal μC_rx, nor does it execute any instructions that arrive at the signal input terminal.

[0062] According to a further embodiment of the present invention, the microcontroller μC further includes a second control output terminal μC_ctl2, and the interface circuit IF has a second control input terminal IF_sw2, which is electrically connected to the control output terminal μC_ctl2. In the above case, both the microcontroller μC and the interface circuit IF also have a third operating mode, and the microcontroller μC is further designed to operate in its third operating mode μC_ctl2. III The command is output at the control output terminal μC_ctl2, which in turn causes the interface circuit IF to operate in its IF mode. III Running in this mode, for example, enabling the microcontroller μC to operate in μC mode. III The control outputs μC_ctl2 and μC_ctl1 both output the corresponding operating mode μC. III And the corresponding instructions for the IF function of the interface circuit.

[0063] To receive and process at least the digital input signal e1 arriving at the connection terminal IF_ext1, according to another embodiment of the invention, the interface circuit IF has a transceiver RS485 and / or a monolithic transceiver compatible with, for example, industry standards IEC 61158CPF15:2007 and / or EIA-485. For example, the same transceiver RS485 can be monolithic, and in some cases, a fault-proof RS485 transceiver, such as the SN65HVD1781 from Texas Instruments Ltd., Dallas, 75265, Texas 75265, 2019, or the THVD2450 from Texas Instruments Ltd., Dallas, 75265, Texas 75265, 2019. Furthermore, it is also provided, such as Figure 5As schematically shown, the transceiver RS485 has at least two bus driver / receiver terminals A and B, at least one digital output terminal R, at least one digital input terminal D, and at least one driver activation input terminal DE. The connection terminal IF_ext1 of the interface circuit IF is formed by means of at least one of the bus driver / receiver terminals A and B, and the signal output terminal IF_tx of the interface circuit IF is formed by means of the digital output terminal R. In the aforementioned case where the microcontroller μC also has a signal output terminal μC_tx and the interface circuit IF has a signal input terminal IF_rx electrically connected to the signal output terminal μC_tx, the signal input terminal IF_rx of the interface circuit can also be formed by means of the aforementioned digital input terminal D of the transceiver RS485. In other cases mentioned, where the microcontroller μC has a control output terminal μC_ctl2 and the interface circuit IF has a control input terminal IF_sw2 electrically connected to the control output terminal μC_ctl2, the control input terminal IF_sw2 of the interface circuit can also be formed by means of the aforementioned driver activation input terminal DE of the transceiver RS485.

[0064] To provide the electrical power P1 required by the microcontroller μC during operation, the electronic unit according to another embodiment of the invention also has a power supply circuit NRG having at least one first power supply terminal U1. Furthermore, the microcontroller μC also has a corresponding power supply terminal, which is additionally electrically connected to the power supply terminal U1 of the power supply circuit NRG. The power supply circuit NRG, for example formed by means of electrochemical and / or rechargeable energy storage, is further designed to provide the microcontroller μC with an operating voltage, such as a unipolar or bipolar DC voltage, at the power supply terminal U1. In contrast, the interface circuit IF is designed to obtain the electrical power or corresponding auxiliary power required during operation, at least sometimes and / or at least partially, from the input signal e1 applied to its connection terminal IF_ext1. For this purpose, the aforementioned signal filter for differentiating the input signal e1 can also advantageously be a passive signal filter, such as a passive high-pass filter formed by means of a simple series circuit of one or more ohmic resistors, which in some cases also acts as a current-limiting resistor.

[0065] According to another embodiment of the present invention, the interface circuit in its operating mode IF I The power requirement is less than 50mW, and / or the interface circuit IF is designed to be used in its operating mode IF. I and operating mode IF IIBoth obtain the required electrical power solely from the input signal e1 applied to the connection terminal IF_rx. The interface circuit IF can also be designed as a passive component of the electronic unit, i.e., it can be configured to obtain the required electrical power P2 during operation entirely or solely from the input signal e1 applied to its connection terminal IF_ext1. Alternatively, the interface circuit IF can also be designed to obtain the required electrical power during operation or auxiliary power proportional to the power supply circuit NRG, and the power supply circuit NRG, as... Figure 2 and Figure 3 As indicated, it can also be designed to provide a portion of the electrical power P2* required by the interface circuit IF during operation, especially for the interface circuit IF in its operating mode. II The power demand is higher than the electrical power nominally fed into the electronic unit by the input signal e1 and / or for the interface circuit in its operating mode IF II The power requirement (P2*) is higher than that of the interface circuit in its operating mode IF. I Given the power demand (P1), the power demand (P2*) is, for example, greater than 150mW.

[0066] To provide the electrical power P2* required by the interface circuit during operation, the power supply circuit NRG according to another embodiment of the invention correspondingly has a second power supply terminal U2. During operation, a temporary operating voltage, such as a unipolar or bipolar DC voltage, is provided to the interface circuit IF at this second power supply terminal U2. The interface circuit IF also correspondingly has a power supply terminal electrically connected to the power supply terminal U2 of the power supply circuit NRG. This is especially relevant to the previously mentioned case where a transceiver RS485 is provided in the interface circuit IF. Figure 5 The instructions or, as shown, should be viewed together. Figure 1 , Figure 2 , Figure 3 and Figure 5 As is readily apparent, the power supply terminals of the interface circuit IF can also be connected, for example, via the two power supply terminals V of the transceiver RS485. CC GND is used to form [the voltage]. To stabilize and / or adjust the voltage level of the operating voltage applied to the aforementioned power supply terminals, [further details are needed]. Figure 5As illustrated, the interface circuit IF can also have a DC / DC voltage converter with a converter input and a converter output. For example, the converter is also currently isolated. The DC / DC voltage converter is designed to convert an input DC voltage applied at the converter input—in this case, the aforementioned operating voltage is applied at the power supply terminal of the interface circuit IF—into an output DC voltage applied at the converter output—which is used as the internal operating voltage of the interface circuit IF and has a voltage level different from the input DC voltage. The DC / DC voltage converter can be, for example, a flyback converter and / or a push-pull converter.

[0067] According to another embodiment of the present invention, the interface circuit IF further includes an electronic main switch HS, and the control input terminal IF_sw1 of the interface circuit IF is also formed by the main switch HS or its control electrode. The main switch HS can be formed, for example, by means of a semiconductor relay (solid-state relay) or by means of an insulated-gate field-effect transistor (IGFET), such as an n-channel MOSFET (NMOS) or another metal-oxide-semiconductor field-effect transistor (MOSFET). Figure 5 As shown, the power supply terminal V of the above interface circuit IF CC GND can be formed using the main switch HS. Specifically, the main switch HS of the interface circuit IF is also specifically designed to switch the operating voltage provided by the aforementioned power supply circuit NRG at power supply terminal U2 from the power supply terminal of the interface circuit IF to other components of the interface circuit IF, such as a possible DC / DC voltage converter and / or a possible RS485 transceiver, only when an activation of its second operating mode IF is applied at the control input terminal IF_sw1 of the interface circuit IF. II When the instruction is given and / or if the third operating mode of the IF is activated at the aforementioned control input IF_sw2 or at both the control input IF_sw2 and control input IF_sw1 of the interface circuit IF, the instruction is given. III This is only done when given an instruction.

[0068] In the case described above where the interface circuit IF has a DC / DC voltage converter, the converter input terminal of the DC / DC voltage converter can be electrically connected to the electronic main switch HS, such that when the electronic main switch HS is turned on at the converter input terminal, the operating voltage for the interface circuit IF provided by the power supply circuit NRG is applied as the input voltage for the DC / DC voltage converter of the interface circuit IF.

[0069] According to another embodiment of the present invention, the interface circuit IF has at least one first optical coupler OK1, which has an optical emitting element and an optical receiving element. Figure 6As schematically shown, the control output terminal IF_ctl of the interface circuit IF is specifically formed by electrically connecting the control input terminal μC_sw of the microcontroller μC via the optical coupler OK1 through its optical receiver element. Furthermore, the interface circuit IF additionally includes a second optical coupler OK2, which is structurally identical to, for example, the optical coupler OK1 and has an optical emitting element and an optical receiver element. The signal output terminal IF_tx of the interface circuit IF is formed by electrically connecting the signal input terminal μC_rx of the microcontroller μC via the optical coupler OK2 through its optical receiver element, as shown below. Figure 6 As indicated. According to an improved embodiment of the invention, the interface circuit IF further includes a third optocoupler OK3, which has an optical emitting element and an optical receiving element and is designed to be identical to, for example, the aforementioned optocoupler OK1 and / or the aforementioned optocoupler OK2. Particularly for the aforementioned case where the interface circuit IF is designed to obtain the electrical power required for operation entirely or solely from the input signal e1 applied to the connection terminal IF_ext1 (passive component), it is also provided that the control input terminal IF_sw1 of the interface circuit IF is formed by means of the optocoupler OK3, such that... Figure 6 As indicated, its optical receiver element is electrically connected to the control output terminal μC_ctl1 of the microcontroller μC. By using optocouplers OK1, OK2, and OK3 to form the control output terminal IF_ctl, the signal output terminal IF_tx, and the control input terminal IF_sw1, the microcontroller μC and the interface circuit IF can advantageously operate in a manner of complete electrical isolation from each other. Correspondingly, complete current isolation between the microcontroller μC and other components of the electronic unit not forming part of the interface circuit IF can also be achieved by external circuitry (e.g., the aforementioned transducer NLU) connected to the interface circuit. In the other case described above, where the interface circuit also has a second control input terminal IF_sw2, according to another embodiment of the invention, the control input terminal IF_sw2 is formed by means of the aforementioned optocoupler OK3, such that, similarly... Figure 7 As shown, the optical emitting element of the optocoupler is electrically connected to the control output terminal μC_ctl2 of the microcontroller μC. Furthermore, to address this, the interface circuit IF also includes a fourth optocoupler OK4, which has an optical emitting element and an optical receiver element. The signal input terminal IF_rx of the interface circuit IF is formed by means of the optocoupler OK4, such that the optical emitting element of this optocoupler is electrically connected to the signal output terminal μC_tx of the microcontroller μC. As a result, when the interface circuit IF is electrically connected to the power supply circuit NRG, at least when the interface circuit IF is in operating mode IF... IDuring operation, current isolation is established between the microcontroller μC and the interface circuit IF. For the aforementioned case where the power supply circuit NRG has a DC / DC voltage converter designed as a flyback converter, when the interface circuit IF is in operating mode IF... II In some cases, it also runs in IF mode. III When running in this mode, the microcontroller μC and the interface circuit IF can also operate in a way that isolates them from each other in terms of current.

Claims

1. An electronic unit, the electronic unit comprising: - Microcontroller (μC) --Has a control input terminal (μC_sw), --Has at least one first control output terminal (μC_ctl1) --And it has a signal input terminal (μC_rx); -and interface circuitry (IF) --Has at least one first connection terminal (IF_ext1), --It has a control output terminal (IF_ctl), --Has a first control input terminal (IF_sw1) --And it has a signal output terminal (IF_tx); -The control output terminal of the interface circuit is electrically connected to the control input terminal of the microcontroller; - wherein the first control output terminal of the microcontroller is electrically connected to the first control input terminal of the interface circuit; -and the signal output terminal of the interface circuit is electrically connected to the signal input terminal of the microcontroller; - wherein both the microcontroller and the interface circuit have a first operating mode (μC) I ;IF I ) and at least a second operating mode (μC) II ;IF II ); - wherein the microcontroller is designed to operate in the first operating mode (μC) I The system outputs an instruction at the first control output terminal, which causes the interface circuit to operate in its first operating mode. -The interface circuit is designed to differentiate the input signal (e1) applied to the first connection terminal, that is, to convert the input signal into a differential signal (a1), the differential signal (a1) representing the differential of the input signal over time, and the interface circuit is designed to at least in the first operating mode (IF) I The differential signal (a1) is used to generate a binary control signal, and the binary control signal is output at the control output terminal (IF_ctl). The control signal causes the microcontroller (μC) to operate in its second operating mode (μC). II The microcontroller is either running in a first operating mode or preparing to switch from its first operating mode to its second operating mode. - wherein the microcontroller is designed to operate in the second operating mode (μC) II Under the first control output terminal (μC_ctl1), the interface circuit (IF) outputs an output that causes the interface circuit (IF) to operate in its second operating mode (IF). II Instructions executed under ( ); -The interface circuit described therein is designed to operate in the second operating mode (IF) II The digital input signal applied to the first connection terminal (IF_ext1) is converted into a binary first output signal (sD1) representing the input signal and the first output signal (sD1) is output at the signal output terminal (IF_tx); -and wherein the microcontroller (μC) is designed to operate in the second operating mode (μC) II It receives and processes the digital input signal applied at the signal input terminal (μC_rx).

2. The electronic unit according to claim 1, wherein the electronic unit is a communication interface or remote I / O of a measurement system and / or a battery-powered electronic unit.

3. The electronic unit according to claim 1, wherein the signal input terminal (μC_rx) is designed as an asynchronous serial interface (UART) or as a switch input terminal.

4. The electronic unit according to claim 1, wherein the interface circuit responds to changes in the logic level of the digital input signal.

5. The electronic unit according to claim 4, wherein the digital input signal conforms to IEC 61158CPF15:2007 and / or EIA-485.

6. The electronic unit of claim 4, wherein the interface circuit responds to changes in the logic level of the digital input signal, the rate of change of which is normalized to a logic level nominally implemented as having a greater than 90% / μs and / or normalized to a signal edge of a binary input signal having an edge steepness greater than 1V / μs when the instruction (IRQ) is encoded as the control signal.

7. The electronic unit according to claim 1, wherein the digital input signal applied to the first connection terminal (IF_ext1) conforms to IEC 61158CPF15:2007 and / or EIA-485.

8. The electronic unit according to claim 1, wherein the digital input signal applied at the signal input terminal (μC_rx) conforms to UART.

9. The electronic unit of claim 1, wherein the microcontroller (μC) is designed to execute instructions contained in the input signal and / or to evaluate messages contained in the input signal.

10. The electronic unit according to any one of claims 1 to 9, -The interface circuit is designed to not convert the digital input signal applied to the first connection terminal into an output signal representing the input signal in the first operating mode, nor to output any output signal representing the digital input signal applied to the first connection terminal at the signal output terminal; and / or - wherein the microcontroller is designed to operate in the first operating mode (μC) I The interface circuit processes the control signal applied at the control input terminal (μC_sw). and / or - wherein the microcontroller is designed to not process the digital input signal applied at the signal input terminal in the first operating mode; and / or - wherein the microcontroller is designed to switch from the second operating mode to the first operating mode in a time-controlled manner; and / or -The interface circuit and the microcontroller are designed to operate simultaneously in their respective second operating modes, such that a first output signal at the signal output terminal of the interface circuit forms a digital input signal applied at the signal input terminal of the microcontroller, and the microcontroller receives and processes the first output signal.

11. The electronic unit of claim 10, wherein the microcontroller is designed to operate in the first operating mode (μC). I By switching to the second operating mode (μC) II It responds to the instruction (IRQ).

12. The electronic unit of claim 10, wherein the microcontroller is designed to not execute the instructions contained in the digital input signal in the first operating mode.

13. The electronic unit of claim 10, wherein the microcontroller is designed to switch from the second operating mode to the first operating mode in a time-controlled manner if no digital input signal and / or UART-compliant input signal is applied at the signal input.

14. The electronic unit according to any one of claims 1 to 9, -The microcontroller (μC) has a signal output terminal (μC_tx), and the interface circuit (IF) has a signal input terminal (IF_rx): - and wherein the signal output terminal (μC_tx) of the microcontroller is electrically connected to the signal input terminal of the interface.

15. The electronic unit according to claim 14, wherein the signal output terminal (μC_tx) of the microcontroller (μC) is designed as an asynchronous serial interface (UART).

16. The electronic unit according to claim 14, wherein the signal input terminal (IF_rx) of the interface circuit (IF) is designed as an asynchronous serial interface (UART).

17. The electronic unit according to any one of claims 1 to 9, - wherein both the microcontroller and the interface circuit have at least a third operating mode (μC) III ;IF III ); -The microcontroller (μC) is designed to output a second digital output signal (sD2) at the signal output terminal (μC_tx) in the third operating mode; -and the interface circuit (IF) described therein is designed to be used in the third operating mode (IF) III The digital input signal applied at the signal input terminal (IF_rx) is converted into a digital third output signal (sD3).

18. The electronic unit of claim 17, wherein the microcontroller (μC) is designed to output a UART-compliant digital second output signal at the signal output terminal (μC_tx) in the third operating mode.

19. The electronic unit of claim 17, wherein the digital input signal applied at the signal input terminal (IF_rx) conforms to UART.

20. The electronic unit according to claim 17, wherein the digital third output signal (sD3) conforms to IEC61158CPF15:2007 and / or EIA-485.

21. The electronic unit according to claim 17, -The interface circuit described therein has a second connection terminal (IF_ext2); - And the interface circuit is designed to output the third output signal (sD3) at the second connection terminal in the third operating mode.

22. The electronic unit according to claim 21, wherein, The interface circuit is designed to not convert the input signal applied at the signal input terminal in the first operating mode and in the second operating mode into an output signal representing the input signal, nor to output any output signal representing the input signal applied at the signal input terminal at the second connection terminal.

23. The electronic unit according to claim 17, wherein, The interface circuit is designed to output the third output signal at the first connection terminal in the third operating mode.

24. The electronic unit according to claim 17, -The microcontroller has a second control output terminal (μC_ctl2) and the interface circuit has a second control input terminal (IF_sw2); - and wherein the second control output terminal of the microcontroller is electrically connected to the second control input terminal of the interface circuit.

25. The electronic unit according to claim 24, wherein, The microcontroller is designed to output instructions in the third operating mode, which cause the interface circuit to operate in its third operating mode at the second control output.

26. The electronic unit according to claim 17, - wherein the microcontroller is designed to switch from the second operating mode to the third operating mode in a manner controlled by an input signal at the signal input terminal; and / or - wherein the microcontroller is designed to automatically switch from the third operating mode to the first operating mode after outputting the digital output signal at the signal output terminal; and / or -The interface circuit is designed to neither convert the input signal applied at the signal input terminal into an output signal applied at the signal input terminal nor output any output signal representing the input signal applied at the signal input terminal at the first connection terminal, in both the first operating mode and the second operating mode. and / or -The microcontroller is designed not to process the digital input signal applied at the signal input terminal in the third operating mode; and / or - wherein the interface circuitry and the microcontroller are designed to operate in their respective third operating modes (μC). III ;IF III The two circuits operate simultaneously, such that the second output signal (sD2) is formed at the signal output terminal (μC_tx) of the microcontroller into a digital input signal applied at the signal input terminal (IF_rx) of the interface circuit, and the interface circuit receives and processes the second output signal (sD2).

27. The electronic unit of claim 26, wherein the microcontroller is designed to not execute any instructions reaching the signal input in the third operating mode.

28. The electronic unit of claim 26, wherein the interface circuit converts the second output signal (sD2) into the third output signal (sD3).

29. The electronic unit according to claim 17, -The interface circuit described herein includes a transceiver (RS485); -And wherein the first connection terminal of the interface circuit is formed by means of at least one of the bus driver / receiver terminals (A, B) of the transceiver, the signal output terminal (IF_tx) of the interface circuit is formed by means of the digital output terminal (R) of the transceiver, and the signal input terminal (IF_rx) of the interface circuit is formed by means of the digital input terminal (D) of the transceiver.

30. The electronic unit of claim 29, wherein the transceiver is compatible with IEC 61158CPF15:2007 and / or EIA-485 and / or is monolithic.

31. The electronic unit of claim 29, wherein the transceiver is a Texas Instruments SN65HVD1781 transceiver from 2019 or a Texas Instruments THVD2450 transceiver from 2019.

32. The electronic unit according to any one of claims 1 to 9, wherein, The interface circuit is designed to obtain the required electrical power solely from the input signal (e1) applied at the first connection terminal in both the first operating mode and the second operating mode.

33. The electronic unit according to any one of claims 1 to 9, further comprising: - Power supply circuit (NRG), -The power supply circuit (NRG) wherein the power supply circuit has at least one first power supply terminal (U1) and is designed to provide the operating voltage to the microcontroller at the first power supply terminal; - and wherein the power supply terminal of the microcontroller is electrically connected to the first power supply terminal (U1) of the power supply circuit (NRG).

34. The electronic unit of claim 33, wherein the power supply circuit is formed by means of electrochemical and / or rechargeable energy storage.

35. The electronic unit according to claim 33, -The power supply circuit (NRG) wherein the power supply circuit has a second power supply terminal (U2) and is designed to provide an operating voltage to the interface circuit at the second power supply terminal; - And the power supply terminal of the interface circuit is electrically connected to the second power supply terminal of the power supply circuit (NRG).

36. The electronic unit according to claim 29 or 35, wherein, The power supply terminals of the interface circuit (IF) are connected via the two power supply terminals (V) of the transceiver (RS485). CC (GND) is formed.

37. The electronic unit according to claim 35, wherein, The interface circuit has an electronic main switch (HS), wherein the first control input terminal (IF_sw1) of the interface circuit and the power supply terminal (V) of the interface circuit (IF) are... CC Both GND and GND are formed by means of the main switch (HS).

38. The electronic unit of claim 37, wherein the electronic master switch (HS) is formed by means of a semiconductor relay or by means of an insulated gate field-effect transistor.

39. The electronic unit according to claim 37, wherein, The interface circuit has a DC / DC voltage converter having a converter input and a converter output, wherein the DC / DC voltage converter is designed to convert an input DC voltage applied at the converter input into an output DC voltage applied at the converter output, having a voltage level different from the input DC voltage.

40. The electronic unit of claim 39, wherein the DC / DC voltage converter is current isolated.

41. The electronic unit of claim 39, wherein the DC / DC voltage converter is a flyback converter or a push-pull converter.

42. The electronic unit according to claim 39, wherein, The converter input terminal of the DC / DC voltage converter is electrically connected to the electronic main switch (HS).

43. The electronic unit of claim 42, wherein when the electronic master switch (HS) is electrically connected, the operating voltage of the interface circuit provided by the power supply circuit (NRG) is applied to the input of the converter.

44. The electronic unit according to any one of claims 1 to 9, wherein, The interface circuit includes a first optical coupler (OK1), which has an optical emitting element and an optical receiving element. The control output terminal of the interface circuit is formed by means of the first optical coupler, such that the optical receiving element of the first optical coupler is electrically connected to the control input terminal of the microcontroller.

45. The electronic unit according to claim 44, wherein, The interface circuit includes a second optical coupler (OK2) having an optical emitting element and an optical receiving element, wherein the signal output terminal of the interface circuit is formed by means of the second optical coupler, such that the optical receiving element of the second optical coupler is electrically connected to the signal input terminal of the microcontroller.

46. ​​The electronic unit according to claim 45, wherein, The interface circuit includes a third optical coupler (OK3), which has an optical emitting element and an optical receiving element.

47. The electronic unit according to claim 46, wherein, The first control input terminal of the interface circuit is formed by means of the third optocoupler, such that the optical receiver element of the third optocoupler is electrically connected to the first control output terminal of the microcontroller.

48. The electronic unit according to claim 46, wherein, The second control input terminal of the interface circuit is formed by means of the third optocoupler, such that the light emitting element of the third optocoupler is electrically connected to the second control output terminal of the microcontroller.

49. The electronic unit according to claim 48, wherein, The interface circuit includes a fourth optical coupler (OK4) having an optical emitting element and an optical receiving element, wherein the signal input terminal of the interface circuit is formed by means of the fourth optical coupler, such that the optical emitting element of the fourth optical coupler is electrically connected to the signal output terminal of the microcontroller.

50. The electronic unit according to any one of claims 1 to 9, wherein, The interface circuit has a filter.

51. The electronic unit according to any one of claims 1 to 9, wherein the interface circuit has a passive signal filter.

52. The electronic unit according to any one of claims 1 to 9, wherein the interface circuit has a high-pass filter.

53. The electronic unit according to any one of claims 1 to 9, wherein, The interface circuit for differentiating the input signal applied to the first connection terminal (IF_ext1) has a high-pass filter.

54. The electronic unit of claim 53, wherein the interface circuit for differentiating the input signal applied to the first connection terminal (IF_ext1) has a passive high-pass filter and / or a high-pass filter having a cutoff frequency greater than 800 Hz.

55. The electronic unit according to any one of claims 1 to 9, -The interface circuitry is designed to obtain, at least temporarily and / or at least partially, the electrical power (auxiliary power) required during operation from the input signal (e1) applied at the first connection terminal; and / or -In the first operating mode, the interface circuit has a power requirement of less than 50mW and / or -The power requirement of the interface circuit in the second operating mode is higher than that of the interface circuit in the first operating mode.

56. The electronic unit of claim 55, wherein the interface circuit is designed to obtain the electrical power required in the first operating mode solely from the input signal (e1) applied to the first connection terminal.

57. The electronic unit according to claim 55, wherein the power requirement of the interface circuit in the second operating mode is greater than 300% and / or greater than 150mW of the power requirement of the interface circuit in the first operating mode.

58. A communication system, comprising: - The electronic unit according to any one of claims 1 to 57 - and a transducer (NLU) electrically connected to the electronic unit; -The transducer (NLU) therein is designed to transmit digital signals to the electronic unit.

59. The communication system of claim 58, wherein the digital signal conforms to IEC 61158CPF15:2007.

60. A measurement system, comprising: - The electronic unit according to any one of claims 1 to 57; - and a sensor electrically coupled to the electronic unit, wherein the microcontroller is designed to receive and evaluate sensor signals generated by means of the sensor, at least in the first operating mode.

61. The measurement system of claim 60, wherein the microcontroller is designed to determine the measurement value of at least one measured variable captured by means of the sensor.

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