Switching device and system with a switching device for generating a differential output signal according to a differential input signal with a diagnostic output signal

Abstract

The invention relates to a switching device (1) for generating a differential output signal (S_DIFF_OUT) according to a differential input signal (S_DIFF_IN) with a diagnostic output signal (S_DIAG_OUT), wherein the differential output signal (S_DIFF OUT) differs from the differential input signal (S_DIFF_IN) in at least one electrical characteristic, wherein errors in the generation of the differential output signal (S_DIFF_OUT) are recognised and mapped in the logic state of the differential output signal (S_DIFF_OUT), wherein a deviation of the logic state of the differential output signal (S_DIFF_OUT) from the logic state of the differential input signal (S_DIFF_IN) is indicated on the diagnostic output signal (S_DIAG_OUT).

Description

[0001] Switching device and system with switching device for generating a differential output signal as a function of a differential input signal with a diagnostic output signal

[0002] Description:

[0003] The invention relates to a switching device and a system with a switching device for generating a differential output signal as a function of a differential input signal with a diagnostic output signal.

[0004] Level converters or level shifters are known as state of the art, which adapt the output signals of an information source to the input signals of an information sink.

[0005] One problem, however, is that during operation of the switching device it is not possible to determine whether the information of the differential output signal always corresponds to the information of the differential input signal.

[0006] From DE 10 2020 001 273 A1, a switching device is known as the closest prior art.

[0007] A system for evaluating signal states is known from DE 10 2019 006 067 A1.

[0008] An integrated circuit arrangement is known from DE 102010 051 873 A1.

[0009] In the present invention, the object is achieved in that error states caused by errors in the signal conversion and / or by errors triggered by a deviation of a monitored electrical property within the switching device are quickly detected, detected error states lead to the rapid switching off of the differential output signal and, in addition, the error status of the switching device is displayed via the diagnostic output signal.

[0010] The invention is therefore based on the object of achieving a high level of diagnostic depth while simultaneously reducing the cost of the diagnostic circuit. According to the invention, this object is achieved by a switching device according to the features specified in claim 1 and by a system with a switching device according to the features specified in claim 14.

[0011] Important features of a switching device according to the invention for generating a differential output signal as a function of a differential input signal with a diagnostic output signal are that the switching device is designed in such a way that the differential output signal differs from the differential input signal in at least one electrical property, wherein errors in the generation of the differential output signal are detected and mapped in the logic state of the differential output signal, wherein a deviation of the logic state of the differential output signal from the logic state of the differential input signal is displayed on the diagnostic output signal.

[0012] A method is therefore carried out for generating a differential output signal, in particular by means of a switching device, as a function of a differential input signal with a diagnostic output signal, wherein the differential output signal differs from the differential input signal in at least one electrical property, wherein errors in the generation of the differential output signal are detected and mapped in the logic state of the differential output signal, wherein a deviation of the logic state of the differential output signal from the logic state of the differential input signal is displayed on the diagnostic output signal.

[0013] A differential or symmetrical signal is a type of signal transmission that enables greater immunity to interference such as common-mode noise over longer transmission paths. Instead of using a single signal conductor, transmission occurs using a pair of identical signal conductors. One signal conductor carries the actual wanted signal, and the other, usually a reference signal known to the receiver. The influence of coupling on the wanted signal along the transmission path is almost identical on both signal conductors if they have the same source impedance, the same line impedance, and the same load impedance. By calculating the difference between the two voltage potentials on the wanted signal conductor and the reference signal conductor, the interference can be removed and the wanted signal restored.A further advantage of differential signal transmission is the achievable shorter signal rise and fall times compared to asymmetric signal transmission, enabling higher signal transmission rates. Electrical properties include, for example, the voltage levels, the maximum load current provided, the maximum switching frequency, and / or the maximum switching times of the differential signals.

[0014] Generation errors are understood to mean all conditions or defects in the switching device that result in either the logic state of the differential input signal not being mapped to the differential output signal and / or the electrical properties being outside their respective specified value ranges.

[0015] Advantageously, the diagnostic output signal is used here as an error collector, which summarizes several errors occurring within the switching device and indicates the error status of the switching device only via the one diagnostic output signal.

[0016] In a further advantageous embodiment, the switching device comprises a differential input stage, a differential output stage and a diagnostic stage, wherein the differential input stage is designed such that it generates at least one internal signal depending on the logic state of the differential input signal, wherein the differential output stage generates the differential output signal, wherein the logic state of the differential output signal results from at least the one internal signal, wherein the electrical properties of the differential output signal are determined by the differential output stage, wherein the diagnostic stage reads back the logic state of the differential output signal and generates the diagnostic output signal depending on the logic state and depending on the at least one internal signal.

[0017] Advantageously, this allows errors in the transmission and conversion of the differential input signal from the signal input of the differential input stage to the signal output of the differential output stage to be detected and displayed. Furthermore, by exchanging or adapting the differential output stage, it is easy to design various switching devices with different electrical properties for their differential output signals.

[0018] In a further advantageous embodiment, the switching device has a supply voltage input and a monitoring stage, wherein the monitoring stage is designed such that the monitoring stage evaluates at least one electrical parameter of the supply voltage input and generates a monitoring signal as a function of each evaluated parameter, wherein the differential output stage is designed such that the logic state of the differential output signal results as a function of at least one internal signal and additionally at least one of the monitoring signals.

[0019] An electrical parameter is understood to be, for example, the flowing electrical current or the electrical voltage.

[0020] Advantageously, the monitoring function is designed separately from the transfer function and the diagnostic function. The monitoring result only affects the differential output, thus reducing the complexity of the switching device and making it easily expandable.

[0021] In a further advantageous embodiment, the differential input stage has three isolating stages, wherein the first isolating stage generates a first internal signal as a function of the differential input signal, wherein the second isolating stage generates a second internal signal as a function of the differential input signal, wherein the third isolating stage generates a third internal signal as a function of the differential input signal, wherein the supply voltage input comprises a supply signal and a ground signal, wherein the monitoring stage generates a first monitoring signal as a function of a first electrical parameter, in particular the electric current flowing through the supply signal, wherein the monitoring stage generates a second monitoring signal as a function of a second electrical parameter, in particular the electric current flowing through the ground signal,wherein the monitoring stage generates a third monitoring signal as a function of a third electrical parameter, in particular the voltage difference between the supply signal and the ground signal, wherein the differential output stage has a high-side output stage and a low-side output stage, wherein the high-side output stage generates a high-side output signal, wherein the logic state of the high-side output signal results from the first signal, the first monitoring signal, and the third monitoring signal, wherein the electrical properties of the high-side output signal are determined by the high-side output stage, wherein the low-side output stage generates a low-side output signal, wherein the logic state of the low-side output signal results from the second signal, the second monitoring signal, and the third monitoring signal,wherein the electrical properties of the low-side output signal are determined by the low-side output stage, wherein the differential output signal results from the difference between the high-side output signal and the low-side output signal, wherein the diagnostic stage has a diagnostic output stage and a diagnostic link stage, wherein the diagnostic link stage reads back the differential output signal and generates at least one diagnostic signal depending on the logic state of the differential output signal and the third signal, wherein the diagnostic output stage uses a diagnostic supply input to generate the diagnostic output signal depending on at least one diagnostic signal.

[0022] An isolator is a circuit element that generates its output signals without interference from its input signals, as can be achieved, for example, by galvanically isolated signal transmission using an optocoupler. Galvanically isolated means that there is no electrical connection between two circuits, allowing both circuits to be powered from different sources.

[0023] The two individual lines of the differential output signal are referred to as the high-side output signal and the low-side output signal, respectively. The high-side refers to the individual line that typically has the higher voltage potential, because it is switched to VCC in the active state, for example. The low-side refers to the individual line that typically has the lower voltage potential, because it is switched to GND in the active state, for example. Finally, the high-side output stage and the low-side output stage refer to the circuit element that generates the respective output signal.

[0024] Advantageously, this arrangement enables separate transmission of the high-side signals and the low-side signals as well as separate generation and monitoring of their electrical parameters.

[0025] In a further advantageous embodiment, the high-side output stage generates a high-side status signal as a function of the first signal, the first monitoring signal and the third monitoring signal, wherein the low-side output stage generates a low-side status signal as a function of the second signal, the second monitoring signal and the third monitoring signal, wherein the diagnostic output stage generates a diagnostic supply signal from the diagnostic supply input, wherein the diagnostic linking stage has a high-side evaluation stage and a low-side evaluation stage, wherein the high-side evaluation stage uses the diagnostic supply signal to generate a high-side diagnostic signal, in particular galvanically isolated, as a function of the high-side output signal and the high-side status signal,wherein the low-side evaluation stage uses the diagnostic supply signal to generate a low-side diagnostic signal, in particular galvanically isolated, depending on the low-side output signal and the low-side status signal, wherein the diagnostic output stage uses the diagnostic supply input to generate the diagnostic output signal depending on the high-side diagnostic signal and the low-side diagnostic signal.

[0026] Advantageously, this circuit arrangement enables extended diagnostics of the differential output stage.

[0027] In a further advantageous embodiment, the differential input stage and the diagnostic stage generate their respective output signals galvanically isolated from their respective input signals.

[0028] Advantageously, this embodiment enables an EMC-optimized use of the switching device according to the invention in a system.

[0029] Important features of a system comprising a safety-related switching device and the switching device according to the invention for generating a differential output signal as a function of a differential input signal with a diagnostic output signal are that the safety-related switching device generates the differential input signal for controlling the switching device and evaluates the diagnostic output signal generated by the switching device, wherein the safety-related switching device carries out at least one error reaction if the diagnostic output signal indicates a deviation of the differential output signal from the differential input signal.A safety-related switching device is a component that monitors a system, whereby the safety-related switching device automatically executes a safety function as a fault reaction when a dangerous fault is detected in order to put the system into a safe state in the event of a fault.The safety-related system monitors the switching device according to the invention and at least one further safety function, such as SAR (Safe acceleration range), SBC (Safe brake control), SBT (Safe brake test), SCA (Safe cam), SDI (Safe direction), SLA (Safely-limited acceleration), SLI (Safely-limited increment), SLP (Safe limited position), SLS (Safely limited speed), SLT (Safely-limited torque), SMT (Safe motor temperature), SOS (Safe operation stop), SP (Safe position), SS1 (Safe stop 1), SS2 (Safe stop 2), SSM (Safe speed monitor), SSR (Safe speed range), STO (Safe torque off), STR (Safe torque range) or any combination of these safety functions.

[0030] Advantageously, this makes it possible to expand the functional scope of the safety-related switching device by the properties of the switching device according to the invention.

[0031] In a further advantageous embodiment, the diagnostic supply input is fed by the safety-related switching device, wherein the safety-related switching device generates test pulses which are transmitted to the switching device via the diagnostic supply input, wherein stuck-at errors are detected on the diagnostic output signal by means of these test pulses.

[0032] Advantageously, this can be used to detect wiring errors in the application of the switching device.

[0033] Further advantages emerge from the dependent claims. The invention is not limited to the combination of features in the claims. Further sensible combinations of claims and / or individual claim features and / or features of the description and / or the figures will become apparent to those skilled in the art, particularly from the problem and / or the problem posed by comparison with the prior art. The invention will now be explained in more detail with reference to the accompanying drawings:

[0034] Figure 1 shows the switching device (1) according to the invention with its external interfaces: the differential input signal S_DIFF_IN, the differential output signal S_DIFF_OUT and the diagnostic output signal S_DIAG_OUT.

[0035] Figure 2 shows the first stage of granularization. The differential input signal S_DIFF_IN is evaluated by the differential input stage (11) and generates the three signals (S11_1, S11_2, S11_3). The differential output stage (12) evaluates two of the signals (S11_1 and S11_2) and generates the differential output signal S_DIFF_OUT. The electrical properties of the differential output signal S_DIFF_OUT are determined solely by the differential output stage. The diagnostic stage (13) uses the signal S11_3 to compare the switching state of the differential input signal S_DIFF_IN with the differential output signal S_DIFF_OUT and reports any deviation on the diagnostic output signal S_DIAG_OUT. This allows any errors in the transmission path to be detected which result in the switching state of the differential input signal S_DIFF_IN not corresponding to the switching state of the differential output signal S_DIFF_OUT.

[0036] Figure 3 shows the switching device still at the first level of granularization. Compared to Figure 2, the switching device (1) has been expanded to include a monitoring stage (14). The differential input signal S_DIFF_IN is evaluated by the differential input stage (11) and generates the three signals (S11_1, S11_2, S11_3). The monitoring stage (14) monitors three electrical parameters (the voltage between VCC and GND, the current through VCC and the current through GND) and generates a monitoring signal (S14_1, S14_2 and S14_3) depending on the monitoring result. The differential output stage (12) evaluates two of the signals (S11_1 and S11_2) and the monitoring signals (S14_1, S14_2 and S14_3) and generates the differential output signal S_DIFF_OUT. The electrical properties of the differential output signal S_DIFF_OUT are determined solely by the differential output stage (12).The diagnostic stage (13) compares the switching state of the differential input signal S_DIFF_IN with the differential output signal S_DIFF_OUT via the signal S11_3 and reports any deviation on the diagnostic output signal S_DIAG_OUT. This allows supply voltage errors to be detected and reported without having to adapt the basic structure of the transmission link. Figure 4 shows the second stage of granularization. The differential input signal S_DIFF_IN is evaluated by three isolating stages (111, 112, 113) in the differential input stage (11). These generate the independent signals S11_1, S11_2, and S11_3. The current through the VCC input is evaluated by a first current monitoring stage (141) in the diagnostic stage (14), and the first monitoring signal S14_1 is generated depending on the result.The current through the GND input is evaluated by a second current monitoring stage (142) in the diagnostic stage (14), and the second monitoring signal S14_2 is generated depending on the result. The voltage between the VCC input and the GND input is evaluated by a voltage monitoring stage (143) in the diagnostic stage (14), and the third monitoring signal S14_3 is generated depending on the result. The high-side output stage (121) in the differential output stage (12) evaluates the signal S11_1 and two of the monitoring signals (S14_1 and S14_3) and generates the high-side output signal S12_1 from them. The electrical properties of the differential high-side output signal S12_1 are determined solely by the high-side output stage (121). The low-side output stage (122) in the differential output stage (12) evaluates the signal S11_2 and two of the monitoring signals (S14_2 and S14_3) and generates the low-side output signal S12_2.The electrical properties of the differential low-side output signal S12_2 are determined solely by the low-side output stage (122). The high-side output signal S12_1 and the low-side output signal S12_2 then combine to produce the differential output signal S_DIFF_OUT. The diagnostic link stage (132) in the diagnostic stage (13) uses the signal S11_3 to compare the switching state of the differential input signal S_DIFF_IN with the differential output signal S_DIFF_OUT and generates at least one diagnostic signal S13_x from the result. The diagnostic output stage (131) in the diagnostic stage (13) uses the additional supply signal S_DIAG_IN to generate the diagnostic output signal depending on at least one of the diagnostic signals S13_x.

[0037] Figure 5 shows a further level of granularization. The differential output stage (12) and the diagnostic stage (13) have been expanded. The differential input signal S_DIFF_IN is evaluated by three isolation stages (111, 112, 113) in the differential input stage (11). These generate the independent signals S11_1, S11_2, and S11_3. The current through the VCC input is evaluated by a first current monitoring stage (141) in the monitoring stage (14), and the first monitoring signal S14_1 is generated depending on the result. The current through the GND input is evaluated by a second current monitoring stage (142) in the monitoring stage (14), and the second monitoring signal S14_2 is generated depending on the result. The voltage between VCC input and GND input is evaluated via a voltage monitoring stage (143) in the monitoring stage (14) and, depending on the result, the third monitoring signal S14_3 is generated.The high-side output stage (121) in the differential output stage (12) evaluates the signal S11_1 and two of the monitoring signals (S14_1 and S14_3) and generates the high-side output signal S12_1 and the high-side status signal S12_3. The electrical properties of the differential high-side output signal S12_1 are determined solely by the high-side output stage (121). The low-side output stage (122) in the differential output stage (12) evaluates the signal S11_2 and two of the monitoring signals (S14_2 and S14_3) and generates the low-side output signal S12_2 and the low-side status signal S12_4. The electrical properties of the differential low-side output signal S12_2 are determined solely by the low-side output stage (122). The high-side output signal S12_1 and the low-side output signal S12_2 then combine to form the differential output signal S_DIFF_OUT.The diagnostic output stage (131) in the diagnostic stage (13) generates a diagnostic supply signal S13_1 from the further supply signal S_DIAG_IN. The high-side evaluation stage (1321) in the diagnostic link stage (132) of the diagnostic stage (13) compares the third signal S11_3 with the high-side status signal S12_3 and the high-side output signal S12_1 and generates the high-side diagnostic signal S13_2 from the result using the diagnostic supply signal S13_1. The low-side evaluation stage (1322) in the diagnostic link stage (132) of the diagnostic stage (13) compares the third signal S11_3 with the low-side status signal S12_4 and the low-side output signal S12_2 and generates the low-side diagnostic signal S13_3 from the result using the diagnostic supply signal S13_1.The diagnostic output stage (131) in the diagnostic stage (13) evaluates the high-side diagnostic signal S13_2 and the low-side diagnostic signal S13_3 and generates the diagnostic output signal S_DIAG_OUT.

[0038] Figure 6 shows the system consisting of the safety-related switching device (2) and the switching device (1) in a typical application. The safety-related switching device (2) controls the switching device (1) via the differential input signal S_DIFF_IN and evaluates the diagnostic output signal S_DIAG_OUT. In addition, the safety-related switching device (2) supplies the additional supply signal S_DIAG_IN. The switching device (1), in turn, controls an electrical load (3) with the differential output signal S_DIFF_OUT.

[0039] The following list of reference symbols is included in the description and explains further features of the invention.

[0040] List of reference symbols

[0041] I Switching device

[0042] II Differential input stage

[0043] III First separation stages

[0044] 112 Second separation stages

[0045] 113 Third separation stages

[0046] 12 differential output stage

[0047] 121 High-side output stage

[0048] 122 Low-side output stage

[0049] 13 Diagnostic Level

[0050] 131 Diagnostic output stage

[0051] 132 Diagnostic link level

[0052] 1321 High-side evaluation stage

[0053] 1322 Low-side evaluation stage

[0054] 14 Monitoring level

[0055] 141 First current monitoring level

[0056] 142 Second current monitoring level

[0057] 143 Voltage monitoring level

[0058] 2 Safety-related switching device

[0059] GND ground signal

[0060] Px Electrical parameter

[0061] P1 First electrical parameter

[0062] P2 Second electrical parameter

[0063] P3 Third electrical parameter

[0064] S_DIAG_IN Additional supply signal

[0065] S_DIAG_OUT diagnostic output signal

[0066] S_DIFF_IN Differential input signal

[0067] S_DIFF_OUT Differential output signal

[0068] S11_x Output signal(s) of the differential input stage

[0069] S11_1 First internal signal of the differential input stage

[0070] S11 2 Second internal signal of the differential input stage

[0071] S11 3 Third internal signal of the differential input stage S12_x Status signal of the diagnostic stage

[0072] S12_1 High-side output signal

[0073] S12_2 Low-side output signal

[0074] S12_3 High-side status signal S12_4 Low-side status signal

[0075] S13_x Diagnostic signal(s)

[0076] S13_1 Diagnostic supply signal

[0077] S13_2 High side diagnostic signal

[0078] S13_3 Low-side diagnostic signal S14_x Monitoring signal(s)

[0079] S14_1 First monitoring signal

[0080] S14_2 Second monitoring signal S14_3 Third monitoring signal VCC supply signal

Claims

Patent claims:

1. Switching device (1) for generating a differential output signal S_DIFF_OUT as a function of a differential input signal S_DIFF_IN with a diagnostic output signal S_DIAG_OUT, characterized in that the differential output signal S_DIFF_OUT differs from the differential input signal S_DIFF_IN in at least one electrical property, wherein errors in the generation of the differential output signal S_DIFF_OUT are detected and mapped in the logic state of the differential output signal S_DIFF_OUT, wherein a deviation of the logic state of the differential output signal S_DIFF_OUT from the logic state of the differential input signal S_DIFF_IN is displayed on the diagnostic output signal S_DIAG_OUT.

2. Switching device (1) according to claim 1, wherein the switching device (1) comprises a differential input stage (11), a differential output stage (12) and a diagnostic stage (13), wherein the differential input stage (11) generates at least one internal signal S11_x depending on the logic state of the differential input signal S_DIFF_IN, wherein the differential output stage (12) generates the differential output signal S_DIFF_OUT, wherein the logic state of the differential output signal S_DIFF_OUT results from at least one internal signal S11_x, wherein the electrical properties of the differential output signal S_DIFF_OUT are determined by the differential output stage (12), wherein the diagnostic stage (13) reads back the logic state of the differential output signal S_DIFF_OUT and generates the diagnostic output signal S_DIAG_OUT depending on the logic state and depending on the at least one internal signal S11_x.

3. Switching device (1) according to claim 2, wherein the switching device (1) has a supply voltage input (VS) and a monitoring stage (14), wherein the monitoring stage (14) evaluates at least one electrical parameter Px of the supply voltage input (VS) and generates a monitoring signal S14_x depending on each evaluated parameter Px.

4. Switching device (1) according to one of the preceding claims, wherein the differential output stage (12) is designed such that the logic state of the differential output signal S_DIFF_OUT results as a function of at least the one internal signal S11_x and additionally at least one of the monitoring signals S14_x.

5. Switching device (1) according to one of the preceding claims, wherein the differential input stage (11) has a first, a second and a third isolating stage (111, 112, 113), wherein the first isolating stage (111) generates a first internal signal S11_1 as a function of the differential input signal S_DIFF_IN, wherein the second isolating stage (112) generates a second internal signal S11_2 as a function of the differential input signal S_DIFF_IN, wherein the third isolating stage (113) generates a third internal signal S11_3 as a function of the differential input signal S_DIFF_IN.

6. Switching device (1) according to claim 2 or 3, wherein the supply voltage input (VS) comprises a supply signal VCC and a ground signal GND.

7. Switching device (1) according to one of the preceding claims, wherein the monitoring stage (14) generates a first monitoring signal S14_1 as a function of a first electrical parameter P1, in particular the flowing electrical current through the supply signal VCC, and / or wherein the monitoring stage (14) generates a second monitoring signal S14_2 as a function of a second electrical parameter P2, in particular the flowing electrical current through the ground signal GND, and / or wherein the monitoring stage (14) generates a third monitoring signal S14_3 as a function of a third electrical parameter P3, in particular the voltage difference between the supply signal VCC and the ground signal GND.

8. Switching device (1) according to one of the preceding claims, wherein the differential output stage (12) has a high-side output stage (121) and a low-side output stage (122), wherein the high-side output stage (121) generates a high-side output signal S12_1, wherein the logic state of the high-side output signal S12_1 results from the first signal S11_1, the first monitoring signal S14_1 and the third monitoring signal S14_3, wherein the electrical properties of the high-side output signal S12_1 are determined by the high-side output stage (121), wherein the low-side output stage (122) generates a low-side output signal S12_2, wherein the logic state of the low-side output signal S12_2 as a function of the second signal S11_2, the second monitoring signal S14_2 and the third monitoring signal S14_3, wherein the electrical properties of the low-side output signal S12_2 are determined by the low-side output stage (122).

9. Switching device (1) according to one of the preceding claims, wherein the differential output signal S_DIFF_OUT results from the difference between the high-side output signal S12_1 and the low-side output signal S12_2.

10. Switching device (1) according to one of the preceding claims, wherein the diagnostic stage (13) has a diagnostic output stage (131) and a diagnostic linking stage (132), wherein the diagnostic linking stage (132) reads back the differential output signal S_DIFF_OUT and generates at least one diagnostic signal S13_x depending on the logic state of the differential output signal S_DIFF_OUT and the third signal S11_3, wherein the diagnostic output stage (131) uses a diagnostic supply input S_DIAG_IN to generate the diagnostic output signal S_DIAG_OUT depending on at least one diagnostic signal S13_x.

11. Switching device (1) according to one of the preceding claims, wherein the high-side output stage (121) generates a high-side status signal S12_3 as a function of the first signal S11_1, the first monitoring signal S14_1 and the third monitoring signal S14_3, wherein the low-side output stage (122) generates a low-side status signal S12_4 as a function of the second signal S11_2, the second monitoring signal S14_2 and the third monitoring signal S14_3.

12. Switching device (1) according to one of the preceding claims, wherein the diagnostic output stage (131) generates a diagnostic supply signal S13_1 from the diagnostic supply input S_DIAG_IN, wherein the diagnostic linking stage (132) has a high-side evaluation stage (1321) and a low-side evaluation stage (1322), wherein the high-side evaluation stage (1321) uses the diagnostic supply signal S13_1 to generate a high-side diagnostic signal S13_2, in particular galvanically isolated, as a function of the high-side output signal S12_1 and the high-side status signal S12_3, wherein the low-side evaluation stage (1322) uses the diagnostic supply signal S13_1 to generate a high-side diagnostic signal S13_2, in particular galvanically isolated, as a function of the low-side output signal S12_2 and the low-side status signal S12_4 to generate a low-side diagnostic signal S13_3, in particular galvanically isolated, wherein the diagnostic output stage (131) uses the diagnostic supply input S_DIAG_IN toto generate the diagnostic output signal S_DIAG_OUT depending on the high-side diagnostic signal S13_2 and the low-side diagnostic signal S13_3.

13. Switching device (1) according to one of the preceding claims, wherein the differential input stage (11) and the diagnostic stage (13) generate their respective output signals galvanically isolated from their respective input signals.

14. System consisting of a safety-related switching device (2) and the switching device (1) according to one of the preceding claims, characterized in that the safety-related switching device (2) generates the differential input signal S_DIFF_IN for controlling the switching device (1) and evaluates the diagnostic output signal S_DIAG_OUT generated by the switching device (1), wherein the safety-related switching device (2) carries out at least one error reaction if the diagnostic output signal S_DIAG_OUT indicates a deviation of the differential output signal S_DIFF_OUT from the differential input signal S_DIFF_IN.

15. System comprising a safety-related switching device (2) and the switching device (1) according to one of the preceding claims or method for detecting errors in such a system, wherein the diagnostic supply input S_DIAG_IN is fed by the safety-related switching device (2), wherein the safety-related switching device (2) generates test pulses which are transmitted to the switching device (1) via the diagnostic supply input S_DIAG_IN, wherein stuck-at errors are detected on the diagnostic output signal S_DIAG_OUT by means of these test pulses.

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