METHOD AND DEVICE FOR EVALUATING SIGNALS COMING FROM AN OSSD OUTPUT ELEMENT

Description

[0001] The invention relates to a method and a circuit for evaluating signals coming from an OSSD output switching element.

[0002] To reduce risks to people or the environment, safety functions are implemented, particularly in automated systems. Simple examples include shutting down a machine after an emergency stop button is pressed or stopping a robot when a person enters the robot's safety zone and, for example, interrupts a light barrier or detects a light grid that monitors the robot's safety zone or opens a monitored access door. For particularly safety-critical processes, it may also be necessary to shut down large sections of a complex system or even the entire system when certain safety functions are activated.

[0003] Safety-related technology, or safety engineering, is used for this purpose. In general, the application of safety engineering implements the actual safety function, such as emergency stop switches, two-hand controls, operating mode selector switches, etc., on the one hand. On the other hand, safety engineering includes fault-detecting and / or fault-control measures, e.g., according to safety requirements defined in standards (e.g., IEC 61508, ISO 13849, etc.). These safety requirements are generally known to the expert.

[0004] Devices and / or signals used within safety technology to implement the safety requirements, which meet the safety requirements, are referred to as safe devices or safe signals in the context of the invention.

[0005] Especially in the field of safety technology, OSSD output switching elements (OSSD, Output Signal Switching Device) are often required, which contain internal output circuits that must be tested according to the safety requirements.

[0006] Diagnosing the shutdown capability of the output circuits is usually performed by briefly shutting down the output drivers assigned to them. However, the shutdown pulses used in this process are visible at the output terminals that terminate the respective output circuits. Therefore, if the outputs of OSSD output switching elements, hereinafter referred to as OSSD outputs, are to be connected to the inputs of input devices, these visible shutdown pulses must pass through an input filter of the input device and be filtered out due to their visibility, especially in the case of safe input devices.

[0007] Typical safe input devices, according to the current state of the art, also generally use their own test outputs to monitor external cabling. Test pulses from the test outputs are then recorded in the input devices. If these pulses are missing, this indicates a cross-circuit in the cabling, and the input devices must react accordingly, thus, especially in the case of safe input devices, entering a safe state.

[0008] If the inputs of the input devices are connected to the OSSD outputs, the input device cannot check the wiring via its own test outputs, as these cannot be interconnected with the OSSD outputs. This means that the input devices have no diagnostics via the wiring, which is not permitted in many applications. One can only hope that the diagnostics of the OSSD outputs are sufficient and that they assume a predetermined, particularly safe, state in the event of a fault. This is not possible, for example, in the case of a cross-circuit to 24V, as the OSSD outputs are bridged in this fault case. In many applications, this fault scenario must therefore be excluded by secure wiring of the lines, which also results in increased costs.

[0009] For example, DE 10 2010 062 310 A1 describes a circuit designed to detect a break in the supply line or a short circuit to ground or 24V. This requires a clock output, which is atypical for safety technology because typical OSSD outputs vary greatly in timing. Furthermore, no information about the status of an OSSD output can be obtained from the clock alone. Therefore, such a solution is limited to special output devices that generate a changing signal when active.

[0010] WO 2007 / 014725 A1 describes a safety switching device for controlling a safety-related device into a safe state. The safety device comprises a first control unit, which is designed as a programmable control unit and has a device for generating a monitoring signal. Furthermore, the safety device comprises a second control device, with an input stage of the safety switching device connected to the first and second control devices. Furthermore, the input stage is designed to modulate an input signal with a monitoring signal coming from the first control device.

[0011] DE 198 05 722 A1 describes a method and device for monitoring electrical lines, in particular for monitoring short circuits. This allows monitoring of OSSD (Output Safety Switching Device) lines, detecting cross-circuits between the lines.

[0012] WO 03 / 085313 A2 relates to a device for fail-safe disconnection of an electrical load. It has a first and at least one second safety switching device. The first safety switching device has a first evaluation and control unit, an output, and an electronic switching element that generates a potential-related switching signal at the output as a function of the first evaluation and control unit. The second safety switching device has a second evaluation and control unit and an input connected to the second evaluation and control unit and to the output of the first safety switching device. The first and second safety switching devices are connected to one another via a single-channel connecting line, and the second safety switching device has at least two input circuits to which the potential-related switching signal of the first safety switching device is supplied redundantly to one another.

[0013] An object of the invention is therefore to provide a way which is improved compared to the prior art and by which effective monitoring for wiring errors can be provided in the case where inputs of circuit arrangements, in particular of safe input devices, are to be connected to OSSD outputs.

[0014] The solution of the invention is provided by an object having the features according to one of the independent claims. Preferred or expedient embodiments and further developments are the subject of the dependent claims.

[0015] The invention accordingly proposes a method for evaluating signals coming from an OSSD output switching element, in which the static and dynamic signal components of signals coming from an OSSD output switching element are separately detected and subsequently evaluated.

[0016] Accordingly, the invention further proposes a device designed in particular for carrying out the method, which device has a first circuit arrangement for evaluating signals coming from an OSSD output switching element, the circuit input of which is to be connected to the output of an OSSD output switching element, wherein the first circuit arrangement has a filter device designed to detect static signal components and to filter out dynamic signal components, and a second circuit arrangement, the circuit input of which is to be connected in parallel to the first circuit arrangement to the output of the OSSD output switching element, the second circuit arrangement having a filter device designed to detect dynamic signal components and to filter out static signal components.The circuit according to the invention further comprises a logic device, wherein the circuit output of the first circuit arrangement and the circuit output of the second circuit arrangement are connected to the logic device, and wherein the logic device is designed to evaluate the static signal components detected by the first circuit arrangement and the dynamic signal components detected by the second circuit arrangement.

[0017] By separately detecting both the static and dynamic signal components of signals coming from an OSSD output switching element and subsequently evaluating them, the invention enables cabling monitoring without the need for special test pulses from the circuitry, particularly within safe input devices, particularly via dedicated test and / or clock outputs. If monitoring the cabling of the circuitry, particularly within safe input devices, is absolutely necessary in the application, a standard solution would only be possible by contact-based decoupling of the OSSD outputs from the circuitry, e.g., via a safety relay, and the use of additional test and / or clock outputs.When using the proposed circuit, this decoupling can be omitted, since cross-circuit monitoring is also available by detecting dynamic signal components and consequently by detecting dynamic OSSD pulses.

[0018] It is also advantageous that the filter device of the first circuit arrangement is constructed from hardware elements or can be constructed on a software basis, so that there is a high degree of flexibility in the design of the filter device and thus enables an application-specific adjustable filter time for filtering out OSSD pulses for detecting the static signal states in the first circuit arrangement.

[0019] According to an expedient embodiment, the second circuit arrangement further comprises a voltage divider for signal adaptation of a signal present at the circuit input of the second circuit arrangement.

[0020] According to an expedient embodiment, the second circuit arrangement has a capacitor for filtering out the static signal components and an optocoupler for transmitting dynamic signal components in the direction of the logic device, wherein a signal adaptation device is preferably arranged between the optocoupler and the logic device, which is designed to adapt a signal received from the optocoupler.

[0021] According to a preferred embodiment, the first and second circuit arrangements are part of a common input device.

[0022] According to a further preferred embodiment, the first circuit arrangement is part of an input device and the second circuit arrangement is part of a second device connected in parallel to the input device, in particular a terminal device, e.g. a diagnostic terminal, which can be installed very easily at a later date and does not affect a safety function of the first circuit arrangement and, moreover, can also supply itself with energy from OSSD output signals, for example, which further reduces the cabling effort.

[0023] Further features and advantages of the invention will become apparent from the following description of preferred embodiments, which is to be considered only as an example, with reference to the accompanying drawings, in which: Fig. 1 an exemplary structure of an input device within the scope of the invention with a preferred embodiment of a device for signal acquisition and for dynamic monitoring of test pulses at OSSD outputs, and Fig. 2 one to Fig. 1 alternative, further preferred embodiment, based on a realization by means of a diagnostic terminal in combination with an input device.

[0024] The following refers to the Fig. 1 and 2 Reference is made to the figures which illustrate two preferred embodiments of the invention, with which, for the evaluation of signals coming from an OSSD output switching element 100, static and dynamic signal components of signals coming from the OSSD output switching element are first separately detected and subsequently detected static signal components as well as detected dynamic signal components can be evaluated.

[0025] For this purpose, each of the devices according to the embodiments according to Fig. 1 and 2 for evaluating signals coming from an OSSD output switching element 100), a first circuit arrangement 220 ( Fig. 1 ) or 220' ( Fig. 2 ), which is to be connected with its circuit input to the output 110, 120 of the OSSD output switching element 100 or is already connected in the illustrated state. The first circuit arrangement has a filter device which is designed to detect static signal components and to filter out dynamic signal components. This first circuit arrangement 220 ( Fig. 1 ) or 220' ( Fig. 2 ) can therefore capture a static state.

[0026] Furthermore, each of the devices comprises a second circuit arrangement 210 ( Fig. 1 ) or 210' ( Fig. 2 ), which is to be connected with its circuit input parallel to the first circuit arrangement equally to the output 110, 120 of the OSSD output switching element 100 or is already connected in the illustrated state. The second circuit arrangement has a filter device which is designed to detect dynamic signal components and to filter out static signal components. This second circuit arrangement 210 ( Fig. 1 ) or 210' ( Fig. 2 ) can therefore detect OSSD pulses.

[0027] Furthermore, each of the devices comprises a logic device 230 ( Fig. 1 ) or 213, 230' ( Fig.2 ), to which the circuit output of the first circuit arrangement and the circuit output of the second circuit arrangement are connected, and which is designed to evaluate the static signal components detected by the first circuit arrangement and the dynamic signal components detected by the second circuit arrangement.

[0028] According to the embodiment according to Fig. 1 the first circuit arrangement 220 and the second circuit arrangement 210 are parts of a common input device 200, in particular a secure input device.

[0029] According to the embodiment according to Fig. 2 only the first circuit arrangement 220' is part of an input device 200', in particular a safe input device, and the second circuit arrangement 210' is part of a second device connected in parallel to this input device, in the case shown part of a diagnostic terminal.

[0030] While in an embodiment according to Fig. 1 Preferably, a common logic device is provided as logic device 230, an embodiment according to Fig. 2 expediently at least two logic devices 230' and 213 as logic device, wherein a first logic device 230' is connected to the circuit output of the first circuit arrangement and a second logic device 213 is connected to the circuit output of the second circuit arrangement.

[0031] As shown in the embodiments Fig. 1 and 2 As can be seen, the OSSD output switching element 100 has, in a simplified sketch, an OSSD output 110 for an OSSD output signal "sOUT" and an OSSD output 120 for ground connection "GND".

[0032] As the first circuit arrangement, which is to be connected with its circuit input to the OSSD output 110 and 120 of the OSSD output switching element 100, any digital input circuit suitable for detecting input signals or suitable for detecting safe input signals within a safe input device can advantageously be used. As already indicated, the task of this first circuit arrangement 220, 220' is to statically detect the signals coming from the OSSD output 110. The dynamic components of these signals can be filtered out within the device according to the invention either by designing the filter device in the hardware of this first circuit arrangement 220, 220' or in the firmware of the logic device 200 or the logic device 230'. The filter time can be expediently parameterized in order to achieve a high degree of flexibility.

[0033] According to the figures, the first circuit arrangement 220 integrated within the input device 200 expediently initially has a voltage divider as a filter device, which in the illustrated case is formed from two resistors R1 and R2. After switching on the first circuit arrangement 220 or 220' with its circuit input to the output 110, 120 of the OSSD output switching element 100, the resistor R1 is further connected to the OSSD output 110 and the resistor R2 is further connected to the OSSD output 120. To filter out the dynamic signal components, a capacitor C1 is provided, which is arranged within the first circuit arrangement 220 between the OSSD output 110 and the OSSD output 120. In the case of the above voltage divider, the capacitor C1 is thus expediently connected in parallel with the resistor R2. The capacitor C1 orAn optocoupler IC1 is in turn connected in parallel with the resistor R2 and the capacitor C1, such that a light-emitting diode located on the input side of the optocoupler IC1 is controlled with the signal adjusted via the voltage divider, wherein dynamic signal components are filtered out via the capacitor C1 and the static signal components are coupled out for further use. The voltage divider can thus be used to adjust the signals coming from the OSSD output switching element 100 for the optocoupler IC1. At the output of the optocoupler IC1, with the help of a DC voltage of e.g. 3.3V and a terminating resistor R3 connected to ground "L_GND", signals can be tapped parallel to the resistor R3, which correspond to the static signal components of the signals coming from the OSSD output switching element 100. The logic device 230 is therefore connected to this tapping point "S" according to. Fig. 1 or the logic device 230' is connected in parallel to the resistor R3, so that the tapped signals are transmitted to the for further evaluation.

[0034] The second circuit arrangement 210 or 210' also expediently initially comprises a voltage divider as a filter device, which in the illustrated case is formed from two resistors R4 and R5. After the second circuit arrangement 210 or 210' is connected with its circuit input to the output 110, 120 of the OSSD output switching element 100, the resistor R4 is thus also connected to the OSSD output 110 and the resistor R5 is thus also connected to the OSSD output 120. To filter out the static signal components, the filter device of the second circuit arrangement 210 or210' has a capacitor C2, which is thus expediently connected between the resistor R4 and the resistor R5, as well as an optocoupler IC2 for transmitting dynamic signal components towards the logic device. A light-emitting diode located on the input side of the optocoupler IC2 is connected downstream of the capacitor C2 in the signal path of the latter and is therefore, according to the figures, also connected in parallel with the resistor R5, in such a way that the light-emitting diode located on the input side of the optocoupler IC2 is controlled with the signal adapted via the voltage divider, wherein the static signal components are filtered out via the capacitor C2 and the dynamic signal components are coupled out for further use. The voltage divider can thus be used to adapt the signals coming from the OSSD output switching element 100 for the optocoupler IC2. At the output of the optocoupler IC2, a DC voltage of, for example, 3.3V and a terminating resistor R6 connected to ground "L_GND", signals are tapped in parallel with the resistor R6, which correspond to the dynamic signal components of the signals coming from the OSSD output switching element 100. At this tapping point "D", a further signal path to the logic device 230 (. Fig. 1 ) or the logic device 213 ( Fig. 2 ) is connected in parallel with the resistor R6, so that the tapped signals are transmitted to it for further evaluation. It is also advisable to connect the optocoupler IC2 and the logic device 230 ( Fig. 1 ) or the logic device 213 ( Fig. 2 ) a signal conditioning device is arranged, which is designed for additional signal conditioning of the signals received from the optocoupler IC2. This signal conditioning device has, as shown in the figures, the resistor R6 and a resistor R7 in the signal path from the tapping point "D" to the logic device 230 ( Fig. 1 ) or to the logic device 213 ( Fig. 2 ) arranged resistor R7. Furthermore, starting from the signal path between the resistor R7 and the logic device 230 ( Fig. 1 ) or the logic device 213 ( Fig. 2 ) a capacitor C3 is connected to ground "L_GND".

[0035] Via the signal conditioning device constructed from the resistors R6 and R7 and the capacitor C3, the tapped signals can be adapted to the respective specific internal structure of the logic device 230 ( Fig. 1 ) or the logic device 213 and, for example, an extension of test pulses for simplified detection by the device firmware and / or an improvement of the EMC behavior can be set. In particular, the pulse duration can be adapted to the processing speed of the logic device 230 ( Fig. 1 ) or the logic device 213.

[0036] The static and dynamic signal components are then evaluated in the logic device 230 or the logic devices 230` and 213, and the information is prepared accordingly for further processing, e.g., in a safety controller (not shown) connected to the logic device 230 via a network.

[0037] According to the embodiment according to Fig. 1 The logic device also expediently carries out a comparison based on the static and dynamic signal components.

[0038] The embodiment according to Fig. 1 This already provides a cost-effective device according to the invention that requires only a few components. As shown above, according to the embodiment according to Fig. 2 The second circuit arrangement 210' can also be implemented as part of a parallel-connected second device, in the illustrated case part of a diagnostic terminal. In this case, a further signal output is preferably provided, Fig. 2 referred to as a diagnostic output, in relation to the second device connected in parallel. If test pulses are missing from the OSSD outputs, a diagnostic output is then activated, whereby an activated diagnostic output should preferably be low-active, which is also evaluated, for example, in the safety controller. By using such a second device, on the one hand, the need for safe cable laying can be avoided in a simple manner, and on the other hand, such a second device can supply itself with energy from the OSSD output 110, 120, which further reduces the cabling effort and can also be installed very easily retrospectively, i.e. at appropriate locations within a given application, without affecting a safety function.

[0039] The solution proposed according to the invention, which has been described above with reference to the two preferred embodiments according to Fig. 1 and2described, thus enables a decoupling of test pulses from OSSD outputs 110, 120 for detecting the signal state, in particular also at the input of a safe input device; the filtering of OSSD pulses for statistical signal detection; the detection of the signal state in an input device; the decoupling of test pulses and processing for the dynamic detection of test pulses from the OSSD outputs in an input device; the detection of test pulses from the OSSD outputs for cabling diagnostics; a predefinable, in particular adjustable filter time for filtering out OSSD pulses for detecting the signal states, in particular also at the input of a safe input device; an adaptation of OSSD pulses for dynamic detection for cabling diagnostics to the processing speed of a subsequent logic device;a predeterminable, in particular adjustable, expectation regarding the frequency of OSSD pulses and a predeterminable, in particular adjustable, expectation regarding the pulse duration of OSSD pulses;

[0040] This allows cabling monitoring to be performed without requiring special test pulses from an input device. If monitoring the cabling in the input device is absolutely necessary in the application, a standard solution would only be possible by contact-based decoupling of the OSSD outputs from the input device, e.g., using a safety relay, and using additional test or clock outputs of the input device. When using the proposed solution according to the invention, this decoupling can be eliminated, since cross-circuit monitoring can be ensured by dynamic detection of OSSD pulses.

[0041] Furthermore, very fast OSSD pulses, e.g. in light barriers in µs range, independent of the static signal acquisition can be monitored cost-effectively and do not require a very fast circuit arrangement or logic processing that is fast enough to capture the short test pulses, since the second circuit arrangement is dimensioned by the signal conditioning device arranged on the output side of the optocoupler IC, according to Fig. 1 and 2 by dimensioning the components R6, R7 and C3, can be adapted to the processing speed of the logic.

[0042] Furthermore, by capturing the dynamic signal components, the behavior of the OSSD outputs is also monitored. If, for example, no pulses are generated while the signal is continuously high, this indicates a cross-circuit to 24V or a defective OSSD output. This monitoring would not be possible with a standard circuit, which poses a safety risk.

[0043] Furthermore, there is a flexible adaptability in the input device, since it is possible to parameterize the expectations regarding the frequency and duration of test pulses of the OSSD outputs.

[0044] In addition, there is the possibility of a predeterminable, in particular adjustable, filter time for filtering out OSSD pulses for detecting the signal states, in particular at the input of a safe input device.

[0045] In the case of an input device, normal operation with other sensors, such as switches, is also still possible, for which the test outputs (not shown in the figures) of the input device are conveniently used.

[0046] With the solution proposed according to the invention, the dynamics on a line can therefore be monitored and combined with the static evaluation of the condition, so that essentially all faults in the cabling can be covered. Bezugszeichen:

[0047] 100 OSSD output switching element 110 OSSD output for OSSD output signal "sOUT" 120 OSSD output for ground connection "GND" 200, 200'Input device 210, 210'Second circuit arrangement; OSSD pulse detection circuit 220, 220'First circuit arrangement; state detection circuit 230, 213, 230'Logic devices STap point DTap point

Claims

1. Device for the evaluation of signals originated by an OSSD output switching element ("OSSD", Output Signal Switching Device; 100) via a cabling, comprising: - a first circuit arrangement (220, 220'), the circuit input of which is to be connected to the output of the OSSD output switching element (100), wherein the first circuit arrangement (220, 220') has a first filter device for the signals, which is designed to detect static signal components and to filter out dynamic signal components, and - a second circuit arrangement (210, 210'), the circuit input of which is to be connected in parallel with the first circuit arrangement (220, 220') equally to the output of the OSSD output switching element (100), wherein the second circuit arrangement (210, 210') has a second filter device for the signals, which is designed to detect dynamic signal components and filter out static signal components, and - a logic device (230, 230', 213), wherein the circuit output of the first circuit arrangement and the circuit output of the second circuit arrangement are connected to the logic device, which is designed to evaluate the static signal components detected by the first circuit arrangement and the dynamic signal components detected by the second circuit arrangement for a diagnosis of the cabling, wherein the first circuit arrangement (220, 220') is part of an input device (200, 200') and the second circuit arrangement (210, 210') is part of a second device connected in parallel with the input device (200, 200') and has a capacitor (C2) for filtering out the static signal components and an optocoupler (IC2) for the transmission of dynamic signal components in the direction of the logic device (230).

2. Device according to claim 1, characterized in that the filter device of the first circuit arrangement (220, 220') is constructed from hardware elements or is software-based.

3. Device according to claim 1 or 2, characterized in that the second circuit arrangement (210, 210') has a voltage divider for signal adaptation of a signal applied to the circuit input of the second circuit arrangement (210, 210').

4. Device according to any one of claims 1 to 3, characterized in that the second circuit arrangement (210, 210') has a signal matching device between the optocoupler and the logic device (230), which is designed for signal adaptation of a signal received from the optocoupler.

5. Device according to one of the preceding claims 1 to 4, characterized in that the logic device (230) comprises at least two logic devices (230', 213), wherein a first logic device (230') is connected to the circuit output of the first circuit arrangement (220, 220') and a second logic device (213) is connected to the circuit output of the second circuit arrangement (210, 210').

6. Device according to one of claims 1 to 5, characterized in that the second device connected in parallel to the input device (200, 200') supplies itself with energy from the signals coming from the output of the OSSD output switching element (100).

7. Device according to one of claims 1 to 6, characterized in that a diagnostic output is provided in relation to the second device connected in parallel, which diagnostic output can be activated in the event of the absence of test pulses from the OSSD outputs.