BE1030961B1 - Device for monitoring a load - Google Patents

Abstract

A device (100) for monitoring a load (102) of an analog output (114) is described. The device (100) comprises a signal converter (110) which has an input (112) and an analog output (114). The signal converter (110) can output an output signal at the analog output (114) depending on an input signal present at the input (112), wherein the output signal is a current or a voltage. A control unit (120) of the device (100) can detect the voltage in addition to the current as an output signal or the current at the analog output (114) in addition to the voltage as an output signal and determine the load (102) from the output signal in combination with the detected current or the detected voltage, and output an indication (104; 106) on the basis of the determined load (102).

Description

1 BE2022/5825

Device for monitoring a load

The invention relates to a device for monitoring a load, in particular at an analog output.

Traditionally, a user is provided with a data sheet specification of the load permissible at the analog output in order to correctly select or adjust the output load connected to the analog output of the connected downstream circuit. This is of particular importance for industrial signal converters with an analog output for a voltage signal, i.e. a voltage output in the range 0...10 V, for example, or a current signal, i.e. a current output in the range 0...20 mA, for example, because failure to comply with the data sheet specification may result in measurement errors, incorrect

control or a complete failure of the output signals can be expected.

For example, a voltage output can generally be operated from 10 kQ and a current output up to 500 Q or 700 Q. The respective limit of the load is determined by the internal structure of the signal converter. In order to be able to drive a load of 10 kQ with a voltage output at full output of 10 V, the output must be able to drive a current of 1 mA. A current output, which has its maximum value of 20 mA, must be able to build up a voltage of 10 V with a load of 500 Q.

If these values are not adhered to, incorrect measured values and non-linearities will occur in the upper range of the characteristic curve for the relationship between the input signal and the output signal of the signal converter.

Value or the corresponding output signal due to a change in the installation of a

If the load connected to the system is not correct, this usually only becomes apparent when

Even if the connected load changes in an unacceptable manner due to ageing or a defect in the system, this can

Operation of the system cannot be detected preventively.

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The invention is therefore based on the object of specifying a technology for determining and/or monitoring a load connected to an analog output. Alternatively or additionally, the object is to achieve monitoring of the connected load with as little additional effort as possible.

The problem is or the problems are solved with the features of the main claim. Expedient embodiments and advantageous further developments of the invention are specified in the dependent claims.

Embodiments of the invention are described below with partial reference to the figures.

According to one aspect of the device, a device for monitoring a load of at least one analog output is provided. The device comprises a signal converter which has at least one input and at least one analog output. The signal converter is designed to output an output signal at the analog output depending on an input signal present at the input. The output signal is (for example either) a current or a voltage. The device further comprises a control unit which is designed to detect the voltage as an output signal in addition to the current or the current at the analog output in addition to the voltage as an output signal. Furthermore, the control unit is designed to determine the load from the output signal in combination with the detected current or the detected voltage and to output an indication based on the determined load.

By allowing the control unit to know the output signal (for example as a setpoint

value) with the detection (e.g. measurement) of the current or voltage as the actual value complementary to the output signal for the determination (e.g.

calculation) of the load, embodiments allow monitoring of the load connected to the analog output by indicating this. Preferably, the detection of the actual value complementary to the output signal is sufficient in order to use the existing knowledge of the output signal and the computing capacity of the

Control to determine the burden, so that embodiments of the device the

Achieve monitoring of the burden with as little additional effort as possible.

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The signal converter can be a measuring transducer, for example according to the standard

DIN 1319. In particular, the signal converter can be a measuring transformer (for example a current transformer or a voltage transformer), a measuring amplifier (for example an isolation amplifier), or a measuring converter (for example with a digital input and at least one analog output).

The load can be a resistance connected to the analog output (for example a total resistance of connecting cables and circuit connected to the analog output) or correspond to such a resistance. Furthermore, the

Burden may optionally include only an active component of the connected resistance and/or no apparent resistance.

The control unit may comprise a microcontroller, for example for determining (in particular calculating) the burden and/or for issuing the indication.

Since the computational effort for determining the load essentially involves division, embodiments of the device can achieve monitoring of the load without increasing the performance of the microcontroller.

The control unit can be a control unit. For example, the control unit can act as a control unit and regulate the output signal (for example, measure it and correct it in response to a deviation from a target value).

The specific burden can also be called connected burden.

The control unit (e.g. according to the device aspect) can control the current or

Record the voltage at the analog output in an analog domain and/or as a measured value. The current recorded at the analog output or the voltage recorded at the analog output

Voltage can be measured in the analog domain and/or recorded as an actual value. An existing analog input of the control unit can advantageously be used for this purpose.

Alternatively or additionally, the control unit can have the output signal in a digital domain and/or as a setpoint value. The output signal can be in a digital domain and/or as a setpoint value of the signal converter (e.g. as a control variable of the control unit or as a reference variable of the output signal as a controlled variable of the

control unit).

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This eliminates the need for a measurement unit for the analog signal and/or the burden can be determined in the digital domain (for example, by calculating a

Division of voltage and current). Advantageously, the output signal can be

Using an analog-digital converter (technical term: "Analog to Digital Converter" or ADC) of the control unit to determine the load. In a first

For example, the output signal can be provided to the control unit independently of the analog output or (in the signal processing direction) before the analog output (for example transmitted by the signal converter). In a second example, the control unit can be designed to determine the target value of the output signal based on the input signal.

The control unit (e.g. according to the device aspect) may further output a limit value of the burden. Alternatively or additionally, the output indication may depend on a comparison of the limit value of the burden with the determined burden. Alternatively or additionally, the output indication may include a residual value of the burden, for example a difference between the limit value of the burden and the determined

Burden output. The residual value of the burden can also be referred to as the reserve of the burden. Examples of implementation can thereby determine the frequency of the output of the

Reduce the amount of information provided or only point out the burden in relevant situations.

The limit of the burden can be an upper limit (i.e. a maximum value) when current is the output signal. The indication can be issued when the specified burden exceeds an upper burden threshold. The upper burden threshold can be 75% to 90% of the upper limit of the burden.

Alternatively or additionally, the limit of the burden when the voltage exceeds

output signal is a lower limit (i.e. minimum value or minimum). The indication can be issued if the specific load has a lower load

The lower burden threshold can be 110% to 125% of the

lower limit of the burden.

The limit value or both limit values or one or both burden threshold values may be stored in a memory (for example in a volatile memory or a read-only memory) of the control unit. For example (preferably

Both the upper and lower limits must be stored (preferably in the case of a signal converter that can be switched between current and voltage as the output signal).

The signal converter (e.g. according to the device aspect) can output the current as an output signal at the analog output, and the control unit can output the indication when the specific load is greater than an upper limit of the load. Alternatively or additionally, the upper limit of the load can correspond to a maximum value of the voltage (e.g. the largest voltage that the signal converter can build up) in order to drive or output a maximum value of the current as an output signal (e.g. an upper limit of a current interval of the output signal). As a result, embodiments of the device can achieve the targeted

Provide an indication of the load on this analog output or one of the analog outputs and/or indicate a precise fault location in a long or complex chain of control signals.

The indication can be issued before the signal converter enters a non-linear region (for example, with regard to the output signal as a function of the input signal). For example, the indication can be issued when the voltage for driving the current as the output signal is less than the maximum value of the voltage. For example, the indication can be issued when the

Voltage to achieve the current as an output signal is less than the maximum voltage value and/or greater than a voltage threshold value. Examples of embodiments of the device can therefore indicate a faulty wiring of the analog output (for example a broken cable or a loose terminal) before a faulty output signal is issued or before the system controlled by the output signal is damaged. The voltage threshold value can be 75% to 90% of the maximum voltage value.

The signal converter (e.g. according to the device aspect) can output the voltage as

Output signal at the analog output, and the control unit can output the indication when the specific load is smaller than a lower limit of the load.

Alternatively or additionally, the lower limit of the burden may be equal to a maximum value of the

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current (e.g. the largest current that the signal converter can drive) in order to build up or output a maximum value of the voltage as an output signal (e.g. an upper limit of a voltage interval of the output signal).

The indication can be issued before the signal converter enters a non-linear region (for example with regard to the output signal as a function of the input signal). For example, the indication can be issued if the current to reach the voltage as an output signal is less than the maximum value of the current and/or greater than a current threshold. Embodiments of the device can thus indicate a faulty state of the analog output (for example a short circuit or moisture) before a faulty output signal is issued or before damage occurs to the system controlled by the output signal. The current threshold can be 75% to 90% of the maximum value of the current.

The device (e.g. according to the device aspect) may further comprise a switch for

Disconnecting the connected load from the analog output. The control unit can also be designed to operate the switch for disconnection (for example, to control it) if the specific load violates the limit value of the load, for example, falls below the lower limit or exceeds the upper limit. Embodiments of the device can thereby prevent (for example thermal) damage to the signal converter and/or the downstream circuit and/or a fire hazard due to a defective electrical connection on the

Avoid analog output.

The switch (e.g. according to the device aspect) may comprise at least one field effect

transistor and/or an electromechanical relay. Alternatively or additionally, the switch can be connected between the analog output of the signal converter and a

Terminal for connecting the load can be arranged electrically. For example, the switch can be designed to electrically connect and electrically separate at least one pole of the analog output of the signal converter and a terminal assigned to the respective pole. The field effect transistor

7 BE2022/5825 can enable a quick separation to avoid thermal damage to the smallest masses in electronic components. The electromechanical relay can ensure galvanic separation, for example if an overvoltage in the circuit connected downstream of the analog output is the cause of the impermissible

burden is.

The device (e.g. according to the device aspect) may further comprise a memory for

Storing the determined burden. Alternatively or additionally, the control unit can also be designed to determine the burden at different times (for example in a time series) and/or for different output signals, and optionally to store the time series and/or a (weighted and/or temporally moving) average or median of the determined burdens in the memory. Embodiments of the device can distinguish between gradual aging and a sudden aging by reading the memory during troubleshooting.

Distinguish defect.

The control unit (e.g. according to the device aspect) can be designed to output the indication or a further indication if the specific burden deviates from the stored burden and/or changes over time (e.g. changes in the time series). Embodiments can thus apply a relative and/or self-adaptive criterion for monitoring the burden (e.g. for outputting the indication) and/or enable (e.g. long-term) monitoring of the burden, for example without predetermination or without input or without adjustment of the (upper and/or lower) burden threshold value of the

Burden (exceeding or falling below which triggers the issuance of the notice).

The control unit (e.g. according to the device aspect) can be designed to provide the indication or a further indication of a short circuit or moisture on the

Analog output when the specific load is less than a predetermined

Minimum value (e.g. the lower burden threshold) and/or (e.g. by at least 10% or 25%) smaller than the stored burden and/or

Decreases over time (for example by at least 50% in a predetermined

time, for example one second).

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Alternatively or additionally, the control unit (e.g. according to the device aspect) can be designed to provide the indication or a further indication of a cable break or a loose electrical connection (e.g. a faulty

terminal point) at the analog output if the specific load is greater than a predetermined maximum value (for example, the upper load threshold) and/or (for example, by at least 10% or 25%) greater than the stored

Burden is and/or increases over time (for example by at least 50% in a predetermined time, e.g. one second) or alternates (for example periodically and/or between two different burden values).

The device (e.g. according to the device aspect) may further comprise a user interface for outputting the determined burden, the limit value or limits (e.g. the upper limit and/or the lower limit), the indication, the further indication and/or the residual value of the burden.

The user interface for outputting the information can output the information locally or via a network interface. For local output, the user interface can include a signal lamp (for example an LED), an acoustic signal generator (for example a loudspeaker) and/or a graphic display (for example for text-based output of the information). Alternatively or additionally, the network interface can include a wired network connection (for example Ethernet) or a wireless network connection. The wireless network connection (for example for a radio network) can be designed in accordance with the IEEE 802.11 (Wi-Fi) standard or a radio access technology of the "Third Generation Partnership Project" (3GPP), for example in accordance with "Long

Term Evolution" (LTE) or the fourth mobile generation (4G) or according to "New

Radio" (NR) or the fifth mobile generation (5G).

Alternatively or additionally, the control unit may comprise a web server. The user interface may comprise a web-based management system.

The control unit (e.g. according to the device aspect) may be further configured to output the determined burden and/or an allowable interval for the burden, optionally by means of a graphical display and/or a web server of the device.

The permissible interval can be the lower limit of the load and/or the upper limit of the

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burden. The determined burden and/or the residual value of the determined burden may be displayed in the interval.

For additional measurement of current or voltage (i.e. complementary to

output signal), the control unit can comprise an analog input which is electrically connected to a measuring point of the signal converter. Alternatively, a digital input of the control unit can be connected to the

Control unit or signal converter must be coupled to the measuring point.

The signal converter (e.g. according to the device aspect) can have a selection signal input. The signal converter can be designed to output either the current or the voltage as the output signal at the analog output depending on a selection signal present at the selection signal input (e.g. detected). In other words, the signal converter can be controllable (e.g. switchable) according to the selection signal, so that the analog output of the signal converter is either a voltage output or a current output.

The selection signal can be output to the selection signal input of the control unit (for example a digital output of the control unit). The selection signal can be output to the selection signal input of the control unit (for example a digital output of the control unit). The control unit can thus be designed to complement the output signal (according to the selection signal) by

The measured voltage recorded at the measuring point is either the current or the voltage at the

Analog output to determine the burden.

The control unit can be designed to be able to measure at the same measuring point depending on the

Selection signal to either measure the voltage in addition to the current as an output signal or the current in addition to the voltage as an output signal.

The invention is explained in more detail below with reference to the accompanying drawings using preferred embodiments which can optionally be combined with one another.

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Show it:

Fig. 1 is a schematic block diagram of a device for monitoring a load of at least one analog output according to a first embodiment;

Fig. 2 is a schematic diagram of a signal generator according to a second

Embodiment which in each embodiment of the device for

can be used to monitor a burden;

Fig. 3 is a schematic block diagram of the device for monitoring a

Burden according to a third embodiment with input and output terminals which in each embodiment of the device for

can be used to monitor a burden;

Fig. 4 schematically shows a display for outputting the determined burden and a

Reserve according to a fourth embodiment, which can be used in any embodiment of the device for monitoring a load for a current signal; and

Fig. 5 schematically shows a display for outputting the determined burden and a

Reserve according to a fifth embodiment, which can be used in any embodiment of the device for monitoring a load for a voltage signal.

Fig. 1 shows a schematic block diagram of a device for monitoring a load of at least one analog output. The device is generally designated by reference numeral 100. The device 100 comprises a signal converter 110 which has at least one input 112. The input 112 can detect (for example receive) input signals from an input device 116.

The input devices 116 can be sensors or isolation transformers. Examples of the sensors 116 are voltage sensors for monitoring the function of a power supply and current sensors for monitoring the load of a consumer (for example an actuator). The input signal can be an analog signal or a digital signal.

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The signal converter 110 can comprise the at least one analog output 114 or can be electrically connected to the at least one analog output 114 on the output side. The signal converter 110 can output an output signal at the analog output 114 depending on an input signal present at the input 112.

For example, the signal converter 110 may comprise an analog-to-digital converter 206 (also: analog-to-digital converter or in technical terms: "analog to digital convertor" or

ADC) which converts the input signal for further processing in a digital domain by a processing unit 208 of the signal converter 110. The

Signal converter 110 may further comprise a digital-to-analog converter (technically known as "digital to analog converter" or DAC) 202, which provides a control signal 201 for

Control of a signal generator 200. The signal generator 200 generates the

Output signal for the analog output 114.

The output signal can be a current signal or a voltage signal. Each analog output 114 outputs the respective output signal to an output device 118. Examples of the output devices 118, which are also referred to as subsequent circuits, are actuators, isolation transformers, impedance matching and

Controllers or their inputs. A typical example of a controller is a programmable logic controller (PLC). The load is a property of the output device 118 that is electrically connected to the respective output 114 of the device 100 and/or the wiring between the output 114 and the output device 118.

While in Fig. 1 the operation of the analog output 114 is shown as a voltage output, the same or corresponding features of the device 100 can be provided for the (for example switchable) operation of the analog output as a current output 114.

The signal converter 110 can also be communicatively connected to a control unit 120. For example, the control unit 120 detects the target value of the output signal (here: the voltage Uson). Alternatively or additionally, the control unit 120 specifies the target value of the output signal. For example, the control unit transmits the control signal corresponding to the output signal to the DAC 202 of the signal converter 110 or to the signal generator 200.

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The control unit 120 detects the voltage at the analog output 114 in addition to the current as an output signal (for example in a switchable state for the

current signal) or in addition to the voltage as an output signal the current (for example in a switchable state for the voltage signal).

As a result, the control unit 120 calculates the burden from the output signal in combination with the detected current (lmess, e.g. as shown in Fig. 1) or the detected

Voltage (Umess).

The control unit 120 may further comprise a user interface 140 (for example, a

Display) such that the control unit 120 can output an indication via the user interface 140 based on the determined burden. The user interface 140 can include, for example, a graphical user interface (e.g., a display) or a web interface to display the determined burden 102 and/or the indication 104, 106 (e.g., a message) to a user.

The user interface 140 may also receive an instruction from the user indicating whether current or voltage should be selected as the output signal. Alternatively or additionally, the control unit 120 may switch between current and voltage as the output signal.

The signal converter 110 can comprise a signal generator 200 which optionally generates the voltage U or the current | as an output signal. The signal converter 110 comprises a selection signal input for a selection signal which specifies whether the control signal 201 is interpreted as a specification for the voltage U and the current | and is output at the analog output 114.

The limit of the burden R, for example the upper limit Rmax of the burden for a

Current output or the lower limit Rmin of the load for a voltage output can be determined by design for the device 100 or in the manufacture of the device 100. During operation and/or for the operation of the device 100, a corresponding limit value of the control signal 201 or the output signal can be derived from the limit value of the load. Alternatively or additionally, the

Voltage as setpoint or output signal of the limit value for the measured

electricity can be diverted.

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Fig. 2 shows a schematic diagram of a signal generator 200 which is connected between

Current signal and voltage signal can be switched according to a second embodiment. The signal generator 200 can be used in any embodiment of the device 100.

In order for the voltage to be the output signal at the analog output 114, the selection transistors 155 are switched to conduct (i.e. closed) in accordance with the selection signal at the selection signal input 154. As a result, the lower pole 114-2 of the analog output 114 is electrically connected to ground. The voltage at pole 114-1 of the analog output 114 is the output signal and is regulated via the feedback 156 to the second input of the operational amplifier in accordance with the control signal present at the first input 201 of the operational amplifier.

In order for the current to be the output signal at the analog output 114, the selection transistors 155 are switched to blocking (i.e. open) in accordance with the selection signal at the selection signal input 154. The current flowing between the poles 114-1 and 114-2 of the current output 114 leads to a proportional voltage drop at the measuring resistors 152 (and thus at the lower pole 114-2 of the analog output 114) compared to the

Ground, which as feedback 158 to the second input of the operational amplifier regulates the current as an output signal according to the control signal 201 present at the first input 201 of the operational amplifier.

The control unit 120 (for example a microcontroller as part of the control unit 120) uses the selection signal to determine whether either a current signal or a voltage signal is output as an output signal at the analog output 114. For example, with a selection signal of 0 V at the selection signal input 154, the output signal is a

current signal (because the bipolar NPN transistor pulls the common gate voltage of the two selection transistors 155 as self-blocking field effect transistors to ground and thus blocks them). With a positive selection signal (for example of 5 V) at the

The output signal of the selection signal input 154 is a voltage signal because the selection transistors are conductive.

The second embodiment of the device 100 for monitoring a load may comprise the signal generator 200 shown schematically in Fig. 2. The signal generator 200 may have a

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Control voltage 201 received (for example, a PWM command) from DAC 202 of device 100.

The signal generator 200 includes measuring resistors 152 for measuring the current as

Output signal, i.e. for measuring the current at the analog output 114 in its function as a current output. For example, a measuring resistor of 50 Ohm can be used for a

A current of 20 mA results in a voltage drop of 1 V.

In one embodiment, the control unit 120 selects the

Analog output 114 as a current output, i.e. the current Ison as an output signal.

The current Iso is specified by the control voltage at the input 201 (i.e. guided and regulated). To calculate the load 102, it is necessary to measure the voltage Umess at the analog output 114 at a measuring point 160 of the signal generator 200. For this purpose, the measuring point 160 can be connected to an analog input of the control unit 120. Alternatively, the control unit 120 or the signal converter 110 (for example the signal generator 200) can have an additional analog-digital

Converter (ADC) 204, which is connected on the input side to the measuring point 160 and on the output side to a digital input of the control unit 120. The ADC 204 converts the voltage Umess of the analog output 114 into a digital value and transmits this to the control unit 120 (e.g. a microcontroller).

In each embodiment, the output signal may correspond to the (for example pulse width modulated, PWM) control signal 201 as a specification. Alternatively or additionally, the current that flows internally for feedback to the operational amplifier may be known to the control unit 120 and calculated out by it.

In a variant of each embodiment of the device 100, the analog output 114 is a current output, for example with the value range (or interval) of 0...20 mA. For example, the control unit 120 controls the analog output 110 for

Output of a current with the maximum value of the interval (e.g. 20 mA) to determine the load.

The following table | shows an example of the output signal as a current signal (for example of 20 mA), the voltage measured at measuring point 160 and the burden calculated based on Ohm's law.

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A circuit-related offset of the burden is, for example, 50 to 60 Q. The internal resistance of 50 to 60 Q (for example, a large part of 50 Q of the internal resistance of 60 ©) drops across the measuring resistor 152 for determining the current as an output signal. The circuit-related offset of the device 100 can be measured by test experiments or calculated directly or by simulation software (e.g. LT-Spice).

The control unit 120 can determine the burden from the current / as output signal, the measured voltage U at the analog output 114 and, if applicable, the offset, for example according to the relationship:

R=UV/,-600 (F1)

Here, U is the voltage at the measuring point 160, / the current signal according to the control signal 201 (e.g. PWM signal) as specification 201 which is to be output as an output signal.

The value of 60 Q given in formula F1 is an example of the circuit-related offset.

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Table I lour Uour burden (controlled by PWM) | (measurement point) | (calculated)

The relationship according to formula F1 only applies up to a limiting voltage (i.e. the maximum value of the voltage) of 12.8 V at the measuring point 160. From then on, a valid output of the current signal (e.g. for a measurement or control) is no longer possible and the control unit 120 issues the information (e.g. an alarm message) via the user interface 140 (e.g. a web-based management, WBM).

The device 100 (or the analog output 114 as a function of the input 112) can operate linearly up to a voltage of 12.6 V at the analog output 114. This results in a maximum load of 570 Q. From the upper limit of 570 Q, the device 100 behaves non-linearly for the maximum value of the current signal (for example, for 20 MA) and from this limit onwards gives incorrect measured values or

Control currents. Since the current is specified as an output signal (i.e. as a target value) or is regulated by the signal generator (for example by means of the operational amplifier as a controller), the load connected to the outside of the device 100 (i.e. the burden), as already mentioned above, is determined from the voltage U at the

Measuring point 160 is calculated. The maximum value of the load (i.e. the upper limit of the burden)

17 BE2022/5825 can be determined in production. The upper limit can possibly be derived directly from the voltage U.

Table II shows another example of the calculated burden based on the

Ohm’s law, the measured voltage at the first measuring point 160 and the

Output signal as current (here: 10 mA). The device 100 can operate linearly up to 12.9 V. This results in an upper limit of the burden of 1230 Q. From the limit of 1230 Q for the 10 mA current, the device behaves non-linearly and from this limit onwards outputs incorrect measured values or too low current signals.

Table II louT UouT Burden (controlled by PWM) | (measurement point 1) | (calculated)

In addition to calculating the burden, the device 100 (for example, the

Control unit 120) can display the determined value of the burden or a residual value (also: reserve) of the burden for the user in the user interface 140, for example in web-based management (WBM) and/or compare or offset it with the upper limit of the device 100.

For example, after switching on the device 100, the externally connected load is determined as described above (preferably by outputting the maximum value of the current as an output signal in the interval) and stored in a memory for further

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Use (for example, during operation of the device 100) until the next calculation.

Example 1: The control unit 120 can perform at least one of the following steps. - The control unit 120 outputs the selection signal for a current signal, for example in response to an input from a user. - The analog output 114 is a current output and (for example via the

Control signal 201 as PWM stage) is set so that 20 mA should flow. - The control unit 120 determines an internal voltage drop (e.g. by simulation software or reading from a memory). - The voltage required for this at terminals 114-1 and 114-2 of the analog output 114 is 9.2 V. This value can be made up of 8 V and an internal voltage drop of 1.2 V (which, for example, is in a

equation). - The determined (e.g. calculated) load is thus R = U/| = (9.2 V - 1.2V) / 20 mA, i.e. R = 400 Q. - The control unit 120 determines that the determined load is in the area of the table | marked OK. - The control unit 120 issues a message on the user interface 140 that the determined load is permissible (i.e. OK).

Example 2: The control unit 120 can carry out at least one of the following steps. - The control unit 120 outputs the selection signal for a current signal, for example in response to a user input. - The analog output 114 is set as a current output so that 20 mA should flow. - The control unit 120 determines an internal voltage drop (e.g. by simulation software or reading from a memory). - The voltage required for this at the terminals is 12.6 V, made up of 11.4 V and the internal voltage drop of 1.2 V. The latter can be calculated out in equation F1.

19 BE2022/5825 - The determined (for example calculated) load is thus R = U/| = (12.6 V - 1.2 V)/20 MA, i.e. R = 570 Q. - The control unit 120 determines that the determined load is in the limit range according to table |. - The control unit 120 outputs the indication to the user interface 140 that the determined load is in the limit range.

Example 3: - The analog output as a current output is set so that 20.0 mA should flow (actually only 19.7 mA flows). - The voltage required at the terminals is 11.6 V + internal voltage drop of 1.2 V (is subtracted in the equation) = 12.8 V. - The calculated load is therefore R = Ul = (12.8 V - 1.2 V) / 19.7 MA, i.e. R = 588 Q > upper limit of the load. - The load is too large (for example in the non-linear range) according to Table |. - The control unit 120 sends a message to the user interface 140 that the specific load is too large or not permissible.

In this case, the device 100 can apply up to 12.8 V to the terminals 114-1 and 114-2 in order to drive the current of 20 mA. It should be noted that this is already the impermissible range of the device 100 (and should be avoided at all costs). The device 100 should have a

message is issued to signal that the load is unacceptably high. The device can indicate this to the user at the user interface 140 (for example via the WBM), optionally together with a calculated remaining

Burden (residual value or reserve) that would still be possible (i.e. connectable).

In the above example case, the limit would already have been reached.

Preferably, the user interface 140 (for example, the WBM) also provides a

Confirmation that or whether the device 100 is within its intended operating range.

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If the user has connected a load that is too large (with I-Out, i.e. current signal as output signal) or too small (with U-Out, i.e. voltage signal as output signal), the user now receives a corresponding message via user interface 140, e.g. by a fault LED lighting up or as an alarm message of a faulty load (for example in the WBM).

Traditionally, a faulty load may not be recognized by the user until a very late stage. In the lower range of the analog output (for example with small currents) it may not be noticed that the load is causing a measurement error, or the error only occurs at larger output values.

Example 4: - Analog output is set as a current output so that 10 mA should flow. - The voltage required for this at terminals 114-1 and 114-2 is 9.6 V. - The calculated load is then R = U/| = 8V / 10 mA, i.e. R = 800 Q.

According to Tables I and II, the device 100 can still apply 11.5 V to the terminals to drive the current of 20 mA. This gives a maximum burden of 575 Ω for a maximum current of 20 mA. The device will now operate linearly in the range up to 14.375 mA and above this current limit will give false readings or too low current signals.

In another embodiment, which can be combined with other embodiments, the control unit 120 selects the analog output as a voltage output using the selection signal. The current flowing through the analog connection 114 is measured via the voltage drop at the measuring resistor 150 at the measuring point 160 before the connection 114-1. The same measuring point is used for this. The measured voltage also goes into a voltage limit, i.e. a maximum value of voltage that the signal generator 200 can build up, as with |-Out (i.e. the aforementioned configuration as a current output). In this case, too, the

21 BE2022/5825 connected load can be determined if the voltage limit has not yet been reached.

In other words, to calculate the burden, a current will be measured by measuring the voltage drop across a measuring resistor 150 (e.g. 10 Ω) as a measurement value complementary to the voltage as the output signal. The measured voltage also goes into a limit that the circuit of the device 100 can provide. The circuit-related offset of the device 100 can be measured by test experiments or calculated directly or by simulation software (e.g. LT-Spice) and/or stored in the control unit 120.

After switching on the device 100, the externally connected burden is determined as described above and stored in a memory for further use (e.g. in operation of the device 100) until the next calculation, e.g. for a different output device 118 or a change in the selected signal.

Preferably, the determined burden is displayed to the user in the user interface 140 and compared or offset against the (e.g. stored) upper limit of the burden.

Table III shows, as an example, the calculated burden based on Ohm’s law, the measured voltage drop across the measuring resistor 150 at the measuring point 160 and the output signal as a voltage signal (here, for example, a target value of 10 V). Due to the known value of the measuring resistor 150 and the known value of the internal resistance (for example, 10Q + 1.2 À), the control unit can calculate the current at the analog output 114 based on the measured voltage drop. The control unit 120 can calculate the burden based on the calculated

current and output voltage.

22 BE2022/5825

Table II!

Ukiemme OUT+ Uauelle Burden (terminal OUT+) | (measuring point) (calculated) 999 | 10004v | 100000 | OK

In a variant of each embodiment, the burden monitoring device 100 may also be used for each determination (e.g. calculation) of the

Burden calculate the possible remaining burden (i.e. the residual value) and divide it by the

user interface 140. The device 100 may further calculate the excess of the burden and present it to the user via the

Output (e.g., display) user interface 140.

If the user In case of U-Out (i.e. a configuration of the analog output as

voltage output), the control unit 120 issues a corresponding indication via user interface 140, e.g. by

Illumination of a fault LED or as an alarm message of a faulty load (for example in the WBM).

Embodiments of the device 100 offer the user the advantage that the connected output load is measured when required or necessary. This not only enables incorrectly connected output loads to be detected, but also a line defect or cable break.

23 BE2022/5825

Fig. 3 shows a block diagram illustrating the input and output terminals of the device 100 according to a third embodiment. The third

The embodiment can further develop individual or all features of the aforementioned embodiments or of Figures 1 or 2. The device 100 can comprise one or more of the inputs 112, each of which is connected to one or more

Input devices 116 are connected or connectable. The embodiment of the device 100 can comprise at least one of the inputs 112 shown in Fig. 3. Alternatively or additionally, the device 100 can be connected or connectable to one or more output devices 118 via the at least one analog output 114. The embodiment of the device 100 can comprise the inputs 112 shown in Fig. 3.

Fig. 3 shown analog output 114 multiple times.

A digital-to-analog converter (DAC) 202 generates a control voltage 201 (for example by means of pulse width modulation, PWM) for a signal generator 200, which

Output signal is generated for the analog output 114. The signal generator 200 can be designed according to the second embodiment or Fig. 2.

The control unit 120 can, for example, as shown schematically in Fig. 3, a

Sends a selection signal to the signal generator 200 indicating which analog output signal is generated and/or which measurement variable complementary to the output signal is measured.

Fig. 4 shows schematically the output of the known current signal (as

output signal) and the measured voltage (as the measurement value complementary to the output signal). In the case of a cable short circuit, the load is zero or almost zero. In the case of an interruption in the cable connection, the load is infinite or very high.

In this example, the burden 102 is determined based on the current signal and the voltage measured at the first measuring point 160. The measured burden 102 is smaller than the upper limit 104 of the burden, i.e. the maximum permissible burden Rmax, for the device 100. The device 100 thus operates in the linear range. Therefore, there is a residual value 106 (also: reserve) of the burden 102 by which the burden 102 could increase and the device 100 could continue to operate in the linear range.

24 BE2022/5825 can. In this example, this means that the device 100 can operate linearly with higher voltage for a defined current signal.

Fig. 5 shows schematically the known voltage signal (as output signal) and the measured current (as the complementary to the output signal)

measured quantity). In the case of a cable short circuit, the burden 102 is minimal or zero, and in the case of a cable connection failure, the burden 102 is very high or infinite.

In this example, the load 102 is determined based on the voltage signal and the measured value (for example by means of the measuring resistors 150) at the measuring point 160.

current. The measured load is greater than the lower limit 104 of the load 102 (i.e. the minimum permissible load Rmin) for the device 100. Thus, the

Device 100 in the linear range. Therefore, there is a so-called residual value 106 (also: reserve) of the burden 102, by which the burden 102 could decrease and the device 100 can continue to operate in the linear range. In this example, this means that the device 100 can operate linearly with a higher current for a defined voltage signal.

Embodiments of the invention offer the user the advantage that the connection load 102 at the output is measured when required or necessary. Alternatively or additionally, not only can an impermissibly connected output load 102 be detected, but also a line defect, a cable break, a loose terminal (for example due to vibrations) or contact corrosion can be determined based on temporal changes in the load and/or threshold values for the load and/or output with the note.

In each embodiment, the output indication may indicate a value (e.g., amount) of the specific load 102 (i.e., the current output load) or a remaining amount 106 (e.g., a distance in ohms) until a limit value 104 of the output load is reached. Alternatively or additionally, the output indication may indicate that the output signal is incorrect. For example, the output indication may indicate that a value measured by means of the signal converter 110 is incorrect (e.g., because the measured

25 BE2022/5825 its value is not correctly represented by the output signal) and/or a connection between the input signal and the output signal does not correspond to a

characteristic curve of the signal converter 110 (for example at a certain

Position of the characteristic curve of the signal converter 110 or at the current position of the characteristic curve of the signal converter). For example, the issued indication can be a non-

Specify linearity between the input signal and the output signal.

Alternatively or additionally, the message issued can indicate at least one of the following errors or causes: - faulty wiring at the analog output 114; - a cable cross-section that is too small at the analog output 114; - a faulty (for example, not correctly tightened) terminal point 114-1 or 114-2 at the analog output 114; - use of an incorrect input or an incorrect input type of a programmable logic controller (PLC) connected to the analog output 114 or other downstream circuit; - incorrect configuration of an input 112 of a PLC connected to the analog output 114 or other downstream circuit; - connection points at the analog output 114 that have become faulty over time, for example due to corrosion, in particular oxidation; and - a cable break at the analog output 114, in particular due to vibration or movement.

In existing signal converters, the current or voltage that the signal converter attempts to output is at best available as an internal setpoint. Even if this is known to the user, it is not easy to calculate and predict the permissible range of the load 102 for a circuit to be connected to the analog output 114 of the signal converter.

Embodiments of the device 100 are therefore designed to determine and monitor the burden 102 connected to the analog output 114.

26 BE2022/5825

Although the invention has been described with reference to exemplary embodiments, it will be apparent to those skilled in the art that various changes may be made and equivalents may be substituted. Furthermore, many modifications may be made to adapt a particular situation or circuit to the teachings of the invention. Accordingly, the invention is not limited to the disclosed embodiments, but includes all embodiments that fall within the scope of the appended claims.

27 BE2022/5825

List of reference symbols

Device for monitoring a load 100

Burden 102

Reference to the limit of the burden, for example upper limit and/or lower limit 104

Reference to residual value (also: reserve) of the burden 106

Device 110 signal converter

Input of the device or signal converter, for example analog input or digital input 112

Analog output of device 114

Input device, for example sensor 116

Output device, e.g. actuator or PLC 118

Control unit of the device, for example microcontroller 120

User interface, for example display 140

Measuring resistor for current at voltage output 150

Measuring resistors for current at current output 152

Dial signal input 154

Wall transistors 155

Feedback to regulate the voltage as output signal 156

Feedback to control the current as an output signal 158

Measuring point 160

Signal Generator 200

Control signal, e.g. control voltage, for signal generator 201

Digital-to-analog converter of device 202

Additional analog-digital converter, for example in signal converter or control unit 204

Analog-digital converter of device 206

Signal processing of the device 208

Claims (15)

28 BE2022/5825 CLAIMS 1. Device (100) for monitoring a load (102) of at least one analog output (114), comprising: a signal converter (110) which has at least one input (112) and at least one analog output (114), wherein the signal converter (110) is designed to output an output signal at the analog output (114) depending on an input signal present at the input (112), wherein the output signal is a current or a voltage; and a control unit (120) which is designed to detect the voltage in addition to the current as an output signal or the current at the analog output (114) in addition to the voltage as an output signal, to determine the load (102) from the output signal in combination with the detected current or the detected voltage, and to output an indication (104; 106) on the basis of the determined load (102). 2. Device (100) according to claim 1, wherein the control unit (120) detects the current or the voltage at the analog output in an analog domain and/or as a measured value, and/or wherein the control unit (120) has the output signal in a digital domain and/or as a target value. 3. Device (100) according to claim 1 or 2, wherein the control unit (120) further outputs a limit value (104) of the burden (102) and/or wherein the output indication (104; 106) depends on a comparison of the limit value of the burden (102) with the determined burden (102) and/or wherein the output indication (104; 106) indicates a residual value (106) of the burden (102) as the difference between the limit value (104) of the burden (102) and the determined burden (102). 4. Device (100) according to one of claims 1 to 3, wherein the signal converter (110) outputs the current as an output signal at the analog output (114), and the control unit (120) outputs the indication (104; 106) when the specific load (102) 29 BE2022/5825 is greater than an upper limit of the burden (102) and/or greater than an upper burden threshold, optionally wherein the upper limit of the burden (102) corresponds to a maximum value of the voltage in order to drive a maximum value of the current as an output signal, and/or wherein the upper burden threshold is 75% to 90% of the upper limit of the burden (102). 5. Device (100) according to one of claims 1 to 4, wherein the signal converter (110) outputs the voltage as an output signal at the analog output (114), and the control unit (120) outputs the indication (104; 106) when the determined burden (102) is less than a lower limit of the burden (102) and/or less than a lower burden threshold value, optionally wherein the lower limit of the burden (102) corresponds to a maximum value of the current in order to achieve a maximum value of the voltage as an output signal, and/or wherein the lower burden threshold value is 110% to 125% of the lower limit of the burden (102). 6. Device (100) according to one of claims 3 to 5, wherein the device (100) further comprises a switch for disconnecting the connected burden (102) from the analog output, wherein the control unit (120) is further configured to actuate the switch for disconnection when the determined burden (102) violates the limit value (104), in particular the lower limit or the upper limit, of the burden (102). 7. Device (100) according to one of claims 1 to 6, wherein the device (100) further comprises a memory for storing the determined burden (102), and/or wherein the control unit (120) is further configured to determine the burden (102) at different times and/or at different output signals, and optionally to store an average value of the determined burdens in the memory. 30 BE2022/5825 8. The device (100) of claim 7, wherein the control unit (120) is further configured to output the indication (104; 106) when the determined burden (102) deviates from the stored burden (102). 9. Device (100) according to one of claims 1 to 8, wherein the control unit (120) is further configured to output an indication (104; 106) of a short circuit or moisture at the analog output (114) if the determined load (102) is less than a predetermined minimum value and/or less than the stored load (102). 10. Device (100) according to one of claims 1 to 9, wherein the control unit (120) is further designed to output an indication (104; 106) of a cable break or faulty terminal point at the analog output (114) if the determined load (102) is greater than a predetermined maximum value and/or greater than the stored load (102). 11. Device (100) according to one of claims 1 to 10, wherein the device (100) further comprises a user interface for outputting the determined burden (102), the indication (104; 106) and/or the residual value (106) of the burden (102). 12. Device (100) according to one of claims 1 to 11, wherein the control unit (114) is further configured to output the determined burden (102) and/or an allowable interval for the burden (102), optionally by means of a graphical display (140) and/or a web server of the device (100). 13. Device (100) according to one of claims 1 to 12, wherein the control unit (120) detects the current or the voltage at the analog output at a measuring point (160) of the signal converter (110), optionally wherein the control unit (120) comprises an analog input which is electrically connected to the measuring point (160), or wherein the control unit (120) comprises a digital input which is electrically connected to the measuring point (160) via an analog-digital converter. 31 BE2022/5825 14. Device (100) according to one of claims 1 to 13, wherein the signal converter (110) has a selection signal input (154) and is designed to output either the current or the voltage as the output signal at the analog output (114) depending on a selection signal present at the selection signal input (154). 15. Device (100) according to claims 13 and 14, wherein the control unit (120) is designed to detect at the same measuring point (160) either the voltage as an output signal in addition to the current or the current as an output signal in addition to the voltage. kk kkk