CN214707666U - Variable analog impedance input circuit and DO card piece for safety relay in SIS system - Google Patents
Variable analog impedance input circuit and DO card piece for safety relay in SIS system Download PDFInfo
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- CN214707666U CN214707666U CN202122252542.6U CN202122252542U CN214707666U CN 214707666 U CN214707666 U CN 214707666U CN 202122252542 U CN202122252542 U CN 202122252542U CN 214707666 U CN214707666 U CN 214707666U
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Abstract
The utility model discloses a variable analog impedance input circuit and DO fastener that is arranged in SIS system safety relay. The variable analog impedance input circuit includes: the circuit comprises a first input end, a second input end, a variable resistance module, a rectifying module and an EMC filtering module; the first end of the variable resistance module is electrically connected with the first input end, the second end of the variable resistance module is electrically connected with the second input end, and the variable resistance module is used for adjusting the impedance value of the part of the variable resistance module, which is connected between the first input end and the second input end; the first end and the second end of the rectifying module are electrically connected with the variable resistance module, the third end and the fourth end of the rectifying module are electrically connected with the EMC filtering module, and the rectifying module is used for inhibiting the capacitive load of the EMC filtering module; the EMC filtering module is used for filtering EMC interference. The utility model discloses a variable analog impedance input circuit can adjust input impedance, and the convenience forms impedance matching with control system, and the system diagnosis function of being convenient for realizes.
Description
Technical Field
The embodiment of the utility model provides a variable impedance technique especially relates to a variable analog impedance input circuit and DO fastener that is arranged in SIS system safety relay.
Background
Impedance matching has important application in modern electronic technology, such as a Safety relay of an SIS (Safety instrumentation System) System, and if impedance between the Safety relay and a System card is not matched, great trouble and trouble are brought to debugging and overhauling of industrial field personnel.
Even if the safety relay has the characteristic of simulating input impedance, the safety relay still cannot be in impedance matching with a system clamping piece due to various field clamping pieces.
SUMMERY OF THE UTILITY MODEL
The utility model provides a variable analog impedance input circuit and DO fastener suitable for safety relay in SIS system to make variable analog impedance input circuit can adjust input impedance, conveniently form impedance match with other systems.
In a first aspect, an embodiment of the present invention provides a variable analog impedance input circuit, which includes: the circuit comprises a first input end, a second input end, a variable resistance module, a rectifying module and an EMC filtering module;
the first end of the variable resistance module is electrically connected with the first input end, the second end of the variable resistance module is electrically connected with the second input end, and the variable resistance module is used for adjusting the impedance value of the part of the variable resistance module, which is connected between the first input end and the second input end;
the first end and the second end of the rectifying module are electrically connected with the variable resistance module, the third end and the fourth end of the rectifying module are electrically connected with the EMC filtering module, and the rectifying module is used for suppressing capacitive load of the EMC filtering module;
the EMC filtering module is used for removing EMC interference.
Optionally, the variable resistance module includes an N-bit dial switch and N first adjusting resistances corresponding to the N-bit dial switch; the ith first adjusting resistor is connected between the first end of the ith switch of the N-bit dial switch and the first end of the variable resistor module, and the second end of the ith switch of the N-bit dial switch is electrically connected with the second end of the variable resistor module; wherein N is an integer greater than or equal to 1, and i is less than or equal to N.
Optionally, the variable resistance module comprises a potentiometer connected between a first end of the variable resistance module and a second end of the variable resistance module.
Optionally, the variable resistance module further comprises: a first short-circuit prevention resistor connected between the potentiometer and the first end of the variable resistance module;
and/or a second short-circuit prevention resistor connected between the potentiometer and the second end of the variable resistance module.
Optionally, the variable resistance module includes N programmable switches and N second adjusting resistors corresponding to the N programmable switches; the ith program-controlled switch is used for controlling whether the ith second adjusting resistor is connected between the first end of the variable resistor module and the second end of the variable resistor module; wherein N is an integer greater than or equal to 1, and i is less than or equal to N.
Optionally, the rectifier module is a rectifier bridge or a diode bridge stack.
Optionally, the EMC filter module includes a first capacitor, a second capacitor, and a common mode inductor, the first capacitor is connected between the third terminal of the rectifier module and the fourth terminal of the rectifier module, the common mode inductor includes a first coil and a second coil, a first end of the first coil is electrically connected to a first end of the first capacitor, a second end of the first coil is electrically connected to a first end of the second capacitor, a second end of the first capacitor is electrically connected to a first end of the second coil, and a second end of the second coil is electrically connected to a second end of the second capacitor.
Optionally, the variable analog impedance input circuit further includes an overvoltage/overcurrent protection module, and the overvoltage/overcurrent protection module is connected between the variable resistance module and the first input terminal and the second input terminal, and is configured to perform overvoltage/overcurrent protection on the variable resistance module.
Optionally, the overvoltage and overcurrent protection module includes: the current limiting resistor, the fuse, the piezoresistor and the transient suppression diode;
the first end of the current-limiting resistor is electrically connected with the first input end, the second end of the current-limiting resistor is electrically connected with the first end of the fuse, and the second end of the fuse is electrically connected with the first end of the variable resistance module;
the voltage dependent resistor is connected between the second end of the current limiting resistor and the second input end, and the transient diode is connected between the second end of the fuse and the second input end.
In a second aspect, the embodiment of the present invention further provides a DO fastener, including a DO fastener body and a first aspect, the variable analog impedance input circuit, the first input end and the second input end of the variable analog impedance input circuit and the DO fastener body are electrically connected.
The technical scheme of the utility model, the variable analog impedance input circuit who adopts includes: the circuit comprises a first input end, a second input end, a variable resistance module, a rectifying module and an EMC filtering module; the first end of the variable resistance module is electrically connected with the first input end, the second end of the variable resistance module is electrically connected with the second input end, and the variable resistance module is used for adjusting the impedance value of the part of the variable resistance module, which is connected between the first input end and the second input end; the first end and the second end of the rectifying module are electrically connected with the variable resistance module, the third end and the fourth end of the rectifying module are electrically connected with the EMC filtering module, and the rectifying module is used for inhibiting the capacitive load of the EMC filtering module; the EMC filtering module is used for filtering EMC interference. The input impedance of the device needing to adjust the impedance matching is changed by adjusting the resistance value of the variable resistance module, so that the device can be flexibly matched with other systems, and the adaptability is stronger. By arranging the EMC filtering module, interference noise and surge between the first input end IN + and the second input end IN-can be filtered, and meanwhile, the external interference noise of the variable analog impedance input circuit is restrained; by arranging the rectifier module between the EMC filter module and the variable resistance module, the voltage on the EMC filter module can be isolated from the voltage between the first input end and the second input end, and the voltage on the EMC filter module is prevented from generating interference on the voltage between the first input end and the second input end of the variable analog impedance input circuit.
Drawings
Fig. 1 is a schematic circuit diagram of a variable analog impedance input circuit according to an embodiment of the present invention;
fig. 2 is a schematic circuit diagram of another variable analog impedance input circuit according to an embodiment of the present invention;
fig. 3 is a schematic circuit diagram of another variable analog impedance input circuit according to an embodiment of the present invention;
fig. 4 is a schematic circuit diagram of another variable analog impedance input circuit according to an embodiment of the present invention.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings and examples. It is to be understood that the specific embodiments described herein are merely illustrative of the invention and are not limiting of the invention. It should be further noted that, for the convenience of description, only some of the structures related to the present invention are shown in the drawings, not all of the structures.
Fig. 1 is a schematic circuit structure diagram of a variable analog impedance input circuit provided in an embodiment of the present invention, referring to fig. 1, the variable analog impedance input circuit includes: the first input end IN +, the second input end IN-, the variable resistance module 1, the rectifier module 2 and the EMC filter module 3; the circuit also comprises a first output end OUT + and a second output end OUT-, wherein the first output end OUT + and the second output end OUT-are used for being connected with a back-end circuit; the first end of the variable resistance module 1 is electrically connected with the first input end IN +, the second end of the variable resistance module 1 is electrically connected with the second input end IN-, and the variable resistance module 1 is used for adjusting the impedance value of the part of the variable resistance module, which is connected between the first input end IN + and the second input end IN-; the first end and the second end of the rectifying module 2 are electrically connected with the variable resistance module 1, the third end and the fourth end of the rectifying module 2 are electrically connected with the EMC filtering module 3, and the rectifying module 2 is used for suppressing capacitive load of the EMC filtering module 3; the EMC filter module 3 is used to filter out ECM disturbances.
Specifically, the variable analog impedance input circuit can be used for being connected to any device (such as a DO card of an SIS system) requiring impedance matching adjustment, the first input terminal IN + and the second input terminal IN-are used for being electrically connected with the device requiring impedance matching adjustment, and after the variable analog impedance input circuit is connected with the device requiring impedance matching adjustment, the input impedance of the device requiring impedance matching adjustment can be changed by adjusting the resistance value of the variable resistance module 1, so that the device can be flexibly subjected to impedance matching with other systems, and the adaptability is stronger. IN addition, by arranging the EMC filtering module 3, the interference noise and surge between the first input end IN + and the second input end IN-can be filtered, and the external interference noise of the variable analog impedance input circuit can be restrained; by arranging the rectifier module 2 between the EMC filter module 3 and the variable resistance module 1, the voltage on the EMC filter module 3 can be isolated from the voltage between the first input end IN + and the second input end IN-, the capacitive load of the EMC filter module 3 and the rear end circuit is suppressed, and the voltage on the EMC filter module 3 is prevented from interfering with the voltage between the first input end IN + and the second input end IN-of the variable analog impedance input circuit.
In the technical solution of this embodiment, the variable analog impedance input circuit includes: the power supply comprises a first input end, a second input end, a variable resistance module 1, a rectifying module 2 and an EMC filtering module 3; the first end of the variable resistance module 1 is electrically connected with the first input end, the second end of the variable resistance module 1 is electrically connected with the second input end, and the variable resistance module 1 is used for adjusting the impedance value of the part of the variable resistance module, which is connected between the first input end and the second input end; the first end and the second end of the rectifying module 2 are electrically connected with the variable resistance module 1, the third end and the fourth end of the rectifying module 2 are electrically connected with the EMC filtering module 3, and the rectifying module 2 is used for suppressing capacitive load of the EMC filtering module 3; the EMC filter module 3 is used for filtering EMC interference. The input impedance of the impedance matching device is required to be adjusted by adjusting the resistance value of the variable resistance module 1, so that the impedance matching device can be flexibly matched with other systems, and the adaptability is stronger. By arranging the EMC filtering module 3, interference noise and surge between the first input end IN + and the second input end IN-can be filtered, and meanwhile, the external interference noise of the variable analog impedance input circuit can be restrained; by arranging the rectifier module 2 between the EMC filter module 3 and the variable resistance module 1, the voltage on the EMC filter module 3 can be isolated from the voltage between the first input terminal and the second input terminal, and the voltage on the EMC filter module 3 is prevented from interfering with the voltage between the first input terminal and the second input terminal of the variable analog impedance input circuit.
Optionally, fig. 2 is a schematic circuit structure diagram of another variable analog impedance input circuit provided in an embodiment of the present invention, referring to fig. 2, the variable resistance module 1 includes an N-bit toggle switch 11 and N first adjusting resistors corresponding to the N-bit toggle switch 11; the ith first adjusting resistor is connected between the first end of the ith switch of the N-bit dial switch 11 and the first end of the variable resistor module 1, and the second end of the ith switch of the N-bit dial switch 11 is electrically connected with the second end of the variable resistor module 1; wherein N is an integer greater than or equal to 1, and i is less than or equal to N.
Specifically, the N-bit dial switch 11 includes N switches, that is, each switch corresponds to a first adjusting resistor from the 1 st switch to the nth switch, IN this embodiment, N is equal to 3 as an example, that is, the N-bit dial switch 11 is a 3-bit dial switch, the 1 st dial switch corresponds to a first adjusting resistor 121, the 2 nd dial switch corresponds to a second first adjusting resistor 122, the 3 rd dial switch corresponds to a third first adjusting resistor 123, by adjusting the switch states of the respective switches IN the 3-bit dial switch, the number of the first adjusting resistors connected between the first input terminal IN + and the second input terminal IN-is changed, that is, the impedance value of the part of the variable resistance module 1 connected between the first input terminal IN + and the second input terminal IN-is adjusted; in this embodiment, by setting the N-bit dial switch and the N first adjusting resistors, the resistance of the variable resistance module 1 can be simply and conveniently adjusted, and the input impedance of the variable analog impedance input circuit can be adjusted. It should be noted that N may have other values in other embodiments. The dial switch may also be a rotary switch or the like.
Optionally, fig. 3 is a schematic circuit structure diagram of another variable analog impedance input circuit provided in an embodiment of the present invention, referring to fig. 3, the variable resistance module 1 includes a potentiometer 131, and the potentiometer 131 is connected between the first end of the variable resistance module 1 and the second end of the variable resistance module 1.
Specifically, IN this embodiment, the effective resistance of the potentiometer 131 can be changed to further change the resistance of the variable resistance module 1, and adjust the input impedance of the variable analog impedance input circuit, and the potentiometer 131 can continuously change the resistance, so as to further expand the range of the resistance of the variable resistance module 1, which is connected between the first input terminal IN + and the second input terminal IN +, so that the adjustment range of the input impedance of the variable analog impedance input circuit is wider, and the application range of the variable analog impedance input circuit is further expanded. Preferably, the potentiometer 131 can be marked with scale values, so that the man-machine interaction is more convenient.
Optionally, with continued reference to fig. 3, the variable resistance module 1 further comprises: a first short-circuit prevention resistor 132, wherein the first short-circuit prevention resistor 132 is connected between the potentiometer 131 and the first end of the variable resistance module 1; and/or a second short-circuit prevention resistor 133, wherein the second short-circuit prevention resistor 133 is connected between the potentiometer 131 and the second end of the variable resistance module 1.
Specifically, the potentiometer 131 may adjust to a state where the effective resistance is zero, and at this time, the potentiometer 131 will short-circuit the first input terminal IN + and the second input terminal IN-, thereby damaging the variable analog impedance input circuit or the device electrically connected to the variable analog impedance input circuit; by setting at least one of the first short-circuit prevention resistor 132 and the second short-circuit prevention resistor 133, the resistance values of the first short-circuit prevention resistor 132 and the second short-circuit prevention resistor 133 are not zero, so that the condition that the effective resistance value of the variable resistance module 1 is zero can be avoided, and the safety of the variable analog impedance input circuit is improved.
Optionally, fig. 4 is a schematic circuit structure diagram of another variable analog impedance input circuit provided in an embodiment of the present invention, and referring to fig. 4, the variable resistance module 1 includes N programmable switches and N second adjusting resistors corresponding to the N programmable switches; the ith program-controlled switch is used for controlling whether the ith second adjusting resistor is connected between the first end of the variable resistor module 1 and the second end of the variable resistor module 1; wherein N is an integer greater than or equal to 1, and i is less than or equal to N.
Exemplarily, in the present embodiment, the example includes 2 programmable switches and two corresponding second adjusting resistors, that is, the first programmable switch 141, the second programmable switch 142, the first second adjusting resistor 151, and the second adjusting resistor 152; the program-controlled switch can be a contact of a relay, the contact of the relay is connected in series with a corresponding second adjusting resistor and then is connected between the first end of the variable resistor module 1 and the second end of the variable resistor module 1, a coil of the relay can be arranged at the background, and whether the corresponding second adjusting resistor is connected between the first input end and the second input end of the variable analog impedance input circuit or not is controlled by controlling whether the coil of the relay is electrified or not; or the program-controlled switch may also be a transistor, for example, the first end of the second adjusting resistor is electrically connected to the first end of the variable resistor module 1, the source of the transistor is electrically connected to the second end of the corresponding second adjusting resistor, the drain of the transistor is electrically connected to the second end of the variable resistor module 1, the control end of the transistor is connected to the control signal, and whether the control end of the transistor loads the conduction signal or not can be remotely controlled, so as to control whether the transistor is conducted or not, that is, whether the corresponding second adjusting resistor is remotely controlled between the first input end and the second input end of the variable analog impedance input circuit or not; that is, the resistance value of the variable resistance module 1 connected between the first input end and the second input end can be adjusted through remote control in the embodiment, the field control is not needed, and the safety is higher. Of course, in other embodiments, the programmable switch may take other forms.
Alternatively, referring to fig. 2 to 4, the rectifier module 2 is a rectifier bridge or a diode bridge stack.
Specifically, the rectifier bridge or the diode bridge stack has the advantages of simple structure, low cost and the like, and by arranging the rectifier module 2 as the rectifier bridge or the diode bridge stack, the influence of capacitive loads such as the EMC filter module 3 and a rear-end circuit on the input impedance can be effectively inhibited, the cost of the variable analog impedance input circuit can be reduced, and polarity conversion can be realized.
Optionally, with continued reference to fig. 2 to 4, the EMC filter module 3 includes a first capacitor 31, a second capacitor 33, and a common mode inductor 32, the first capacitor 31 is connected between the third terminal of the rectifier module 2 and the fourth terminal of the rectifier module 2, the common mode inductor 32 includes a first coil L1 and a second coil L2, a first terminal of the first coil L1 is electrically connected to the first terminal of the first capacitor 31, a second terminal of the first coil L1 is electrically connected to the first terminal of the second capacitor 33, a second terminal of the first capacitor 31 is electrically connected to the first terminal of the second coil L2, and a second terminal of the second coil L2 is electrically connected to the second terminal of the second capacitor 33.
Specifically, the first capacitor 31, the common mode inductor 32 and the second capacitor 33 form a pi-type filter circuit, and the pi-type filter circuit has a simple structure, can effectively filter EMC interference signals, and ensures the working stability of the variable analog impedance input circuit. A first terminal of the second capacitor 33 may serve as a first output terminal OUT + of the variable analog impedance input circuit, and a second terminal of the second capacitor 33 may serve as a second output terminal OUT-of the variable analog impedance input circuit.
Optionally, with continued reference to fig. 2 to 4, the variable analog impedance input circuit further includes an overvoltage/overcurrent protection module 4, where the overvoltage/overcurrent protection module 4 is connected between the variable resistance module 1 and the first input terminal IN + and the second input terminal IN-, and is configured to perform overvoltage/overcurrent protection on the variable resistance module 1.
Specifically, the overvoltage/overcurrent protection module 4 can prevent the variable resistor module 1 from being burned out when the voltage or the current is too large, and can further ensure the working stability of the variable analog impedance input circuit and prolong the service life of the variable analog impedance input circuit.
Illustratively, with continued reference to fig. 2-4, the overvoltage overcurrent protection module includes: a current limiting resistor 41, a fuse 42, a voltage dependent resistor 43 and a transient suppression diode 44; a first end of the current limiting resistor 41 is electrically connected with the first input end IN +, a second end of the current limiting resistor 41 is electrically connected with a first end of the fuse 42, and a second end of the fuse 42 is electrically connected with a first end of the variable resistance module 1; the voltage dependent resistor 43 is connected between the second terminal of the current limiting resistor 41 and the second input terminal IN-, and the transient suppression diode 44 is connected between the second terminal of the fuse 42 and the second input terminal IN-.
Specifically, the current limiting resistor 41 and the fuse 42 form a series structure, and when the current in the loop is too large, the fuse 42 is disconnected, so that the variable analog impedance input circuit is subjected to current protection; the voltage dependent resistor 43 and the transient suppression diode 44 are connected IN parallel between the first input terminal IN + and the second input terminal IN-, when an overvoltage appears across the voltage dependent resistor 43, the voltage dependent resistor can limit the voltage to a fixed value, and the transient suppression diode 44 can absorb the transient high energy across the voltage dependent resistor to clamp the voltage across the voltage dependent resistor to a predetermined value, thereby performing overvoltage protection on the variable analog impedance input circuit.
In this embodiment, the variable analog impedance input circuit is formed by discrete devices, and the discrete devices are easy to select, purchase, produce and the like, and have high reliability.
The embodiment of the utility model provides a DO fastener is still provided, variable impedance device include DO fastener body with the utility model discloses arbitrary embodiment provides a variable analog impedance input circuit, variable analog impedance input circuit's first input and second input are connected with DO fastener body electricity. Because it includes the variable analog impedance input circuit that the utility model discloses arbitrary embodiment provided, therefore also have the same beneficial effect, no longer describe herein.
It should be noted that the foregoing is only a preferred embodiment of the present invention and the technical principles applied. It will be understood by those skilled in the art that the present invention is not limited to the particular embodiments described herein, but is capable of various obvious changes, rearrangements and substitutions as will now become apparent to those skilled in the art without departing from the scope of the invention. Therefore, although the present invention has been described in greater detail with reference to the above embodiments, the present invention is not limited to the above embodiments, and may include other equivalent embodiments without departing from the scope of the present invention.
Claims (10)
1. A variable analog impedance input circuit for a safety relay in an SIS system, the variable analog impedance input circuit comprising: the circuit comprises a first input end, a second input end, a variable resistance module, a rectifying module and an EMC filtering module;
the first end of the variable resistance module is electrically connected with the first input end, the second end of the variable resistance module is electrically connected with the second input end, and the variable resistance module is used for adjusting the impedance value of the part of the variable resistance module, which is connected between the first input end and the second input end;
the first end and the second end of the rectifying module are electrically connected with the variable resistance module, the third end and the fourth end of the rectifying module are electrically connected with the EMC filtering module, and the rectifying module is used for suppressing capacitive load of the EMC filtering module;
the EMC filtering module is used for removing EMC interference.
2. The variable analog impedance input circuit for a safety relay in an SIS system of claim 1, wherein the variable resistance module comprises an N-bit dial switch and N first adjusting resistors corresponding to the N-bit dial switch; the ith first adjusting resistor is connected between the first end of the ith switch of the N-bit dial switch and the first end of the variable resistor module, and the second end of the ith switch of the N-bit dial switch is electrically connected with the second end of the variable resistor module; wherein N is an integer greater than or equal to 1, and i is less than or equal to N.
3. The variable analog impedance input circuit for a safety relay in an SIS system of claim 1, wherein the variable resistance module comprises a potentiometer connected between a first end of the variable resistance module and a second end of the variable resistance module.
4. The variable analog impedance input circuit for a safety relay in an SIS system of claim 3, wherein the variable resistance module further comprises: a first short-circuit prevention resistor connected between the potentiometer and the first end of the variable resistance module;
and/or a second short-circuit prevention resistor connected between the potentiometer and the second end of the variable resistance module.
5. The variable analog impedance input circuit for a safety relay in an SIS system of claim 1, wherein the variable resistance module comprises N programmable switches and N second adjusting resistors corresponding to the N programmable switches; the ith program-controlled switch is used for controlling whether the ith second adjusting resistor is connected between the first end of the variable resistor module and the second end of the variable resistor module; wherein N is an integer greater than or equal to 1, and i is less than or equal to N.
6. The variable analog impedance input circuit for a safety relay in an SIS system of claim 1, wherein the rectification module is a rectifier bridge or a diode bridge stack.
7. The variable analog impedance input circuit for a safety relay in an SIS system of claim 1, wherein the EMC filtering module comprises a first capacitor, a second capacitor and a common mode inductor, the first capacitor is connected between a third terminal of the rectifying module and a fourth terminal of the rectifying module, the common mode inductor comprises a first coil and a second coil, a first terminal of the first coil is electrically connected with a first terminal of the first capacitor, a second terminal of the first coil is electrically connected with a first terminal of the second capacitor, a second terminal of the first capacitor is electrically connected with a first terminal of the second coil, and a second terminal of the second coil is electrically connected with a second terminal of the second capacitor.
8. The variable analog impedance input circuit for a safety relay in an SIS system according to claim 1, further comprising an over-voltage over-current protection module connected between the variable resistance module and the first and second input terminals for over-voltage over-current protection of the variable resistance module.
9. The variable analog impedance input circuit for a safety relay in an SIS system of claim 8, wherein the over-voltage over-current protection module comprises: the current limiting resistor, the fuse, the piezoresistor and the transient suppression diode;
the first end of the current-limiting resistor is electrically connected with the first input end, the second end of the current-limiting resistor is electrically connected with the first end of the fuse, and the second end of the fuse is electrically connected with the first end of the variable resistance module;
the voltage dependent resistor is connected between the second end of the current limiting resistor and the second input end, and the transient suppression diode is connected between the second end of the fuse and the second input end.
10. A DO clip comprising a DO clip body and the variable analog impedance input circuit for a safety relay in an SIS system of any of claims 1-9, the first and second inputs of the variable analog impedance input circuit being electrically connected to the DO clip body.
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| CN202122252542.6U CN214707666U (en) | 2021-09-17 | 2021-09-17 | Variable analog impedance input circuit and DO card piece for safety relay in SIS system |
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| CN202122252542.6U CN214707666U (en) | 2021-09-17 | 2021-09-17 | Variable analog impedance input circuit and DO card piece for safety relay in SIS system |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN114024522A (en) * | 2021-12-20 | 2022-02-08 | 广州国家实验室 | Resistor network, device and method for simulating lung respiration |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN114024522A (en) * | 2021-12-20 | 2022-02-08 | 广州国家实验室 | Resistor network, device and method for simulating lung respiration |
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