Method for fault diagnosis and diagnosis circuit for foundation fieldbus

Abstract

The application provides a fault diagnosis method and diagnosis circuit for a foundation field bus. The foundation field bus comprises a field device side (100) and a cabinet side (200), and the fault diagnosis method comprises the following steps: A. the bus terminal (9) of the network communication module (4) of the field device side (100) is kept in communication power supply, and the wiring terminal (3) of the cabinet side (200) is kept in communication power supply; the voltage range of a multimeter circuit (7) is connected with the '+' end and the '-' end of the wiring terminal (3) on one side respectively, and connected with the ground (82) of the cabinet side (200) on the other side; if the obtained voltage value is greater than the reference voltage of the foundation field bus, it is a fault.

Description

Technical Field

[0001] This invention relates to a fault diagnosis method and diagnostic circuit for Foundation Fieldbus. Background Technology

[0002] Foundation Fieldbus (FF) is widely used in process automation. FF fieldbus instrument communication technology refers to the technology that enables communication between multiple instruments connected to a single bus cable (referred to as a network segment). Figure 1 As shown, segment 1 represents the bus cable 6 and the device 300 installed between a pair of RC terminators 5. The advantages of this technology are that it greatly reduces the amount of cable laying and enables centralized digital communication and signal processing. However, it also has corresponding disadvantages. When a segment fails, multiple instruments on the segment will malfunction, which will have a significant impact on the process operation.

[0003] Currently, common methods for troubleshooting include powering off and restarting the network segment and using vendor-specific instruments (such as FBT6) to test network communication. However, the inventors found that these methods are ineffective, often resulting in recurring faults. Furthermore, current methods only allow troubleshooting after a fault occurs on the FF fieldbus and affects the corresponding equipment, making prevention difficult. Additionally, the long length of the FF fieldbus network segment makes fault diagnosis challenging, as is accurately pinpointing the fault location and the troubleshooting process is cumbersome. The operation of instruments on the network segment also hinders the troubleshooting process. Summary of the Invention

[0004] The purpose of this invention is to provide a fault diagnosis method for Foundation Fieldbus.

[0005] Another object of the present invention is to provide a diagnostic circuit for Foundation Fieldbus.

[0006] According to one aspect of the present invention, a fault diagnosis method for a Foundation Fieldbus includes a field device side and a cabinet side. The fault diagnosis method includes: A. The bus terminals of the network communication module on the field device side are kept connected and powered, and the wiring terminals on the cabinet side are kept connected and powered; the voltage range of a multimeter circuit is connected to the "+" and "-" terminals of the wiring terminals on one side, and to the ground on the cabinet side on the other side. If the obtained voltage value is greater than the reference voltage of the Foundation Fieldbus, then a fault is found.

[0007] By employing online voltage measurement, no power outage of the network segment is required. Diagnostic measurements are performed using the voltage range of a multimeter circuit. This allows for regular monitoring of the operational health of the Foundation fieldbus, ensuring normal online operation of equipment while efficiently completing diagnostics. It can play a preventative role before faults occur, preventing Foundation fieldbus failures from affecting the operation of corresponding equipment and ensuring the normal operation of the corresponding production equipment to avoid impacting production efficiency.

[0008] In one or more embodiments of the Foundation fieldbus fault diagnosis method, the fault diagnosis method further includes: B. If A is determined to be a fault, the bus terminals of the network communication module on the field device side are disconnected, while the wiring terminals on the cabinet side remain connected and powered; the resistance setting of the multimeter circuit is connected to each terminal of the bus terminal on one side, and to the ground on the field device side on the other side; if the obtained resistance value is a non-open circuit resistance value, then the network communication module and branch circuits are faulty, and the branch terminal circuits of the network communication module on the field device side are disconnected one by one; if a certain branch... If the resistance obtained after the terminal circuit is disconnected is an open circuit resistance, then the branch terminal circuit is diagnosed as faulty; C. The bus terminal of the network communication module on the field device side is disconnected, and the wiring terminal on the cabinet side is disconnected; the resistance setting of the multimeter circuit is connected to each end of the bus terminal on one side, and the other side is connected to the ground on the field device side; D. The bus terminal of the network communication module on the field device side is disconnected, and the wiring terminal on the cabinet side remains connected for power supply; the resistance setting of the multimeter circuit is connected to each end of the wiring terminal on one side, and the other side is connected to the ground on the cabinet side.

[0009] The beneficial effects of the above embodiments are that by adopting the offline resistance measurement method, and by disconnecting the power to the network segment and using the resistance range of a multimeter circuit for diagnostic measurement, the fault point can be quickly and accurately located when a fault occurs in the network segment. This simplifies the fault diagnosis process of the Foundation Fieldbus, greatly improves the efficiency of fault diagnosis, and saves on fault diagnosis costs. It also makes the fault diagnosis process simple, fast, accurate, and efficient, and greatly improves the operational reliability of the Foundation Fieldbus.

[0010] In one or more embodiments of the Foundation Fieldbus fault diagnosis method, the voltage range of the multimeter circuit is connected in series with a first resistor on one side, the sum of the resistance of the voltage range and the resistance of the first resistor being greater than or equal to the ground resistance threshold specified by the Foundation Fieldbus.

[0011] In one or more embodiments of the Foundation Fieldbus fault diagnosis method, the Foundation Fieldbus specifies a ground resistance threshold of 20 MΩ, and the sum of the resistance of the voltage level and the resistance of the first resistor is 21 MΩ to 101 MΩ.

[0012] In one or more embodiments of the Foundation Fieldbus fault diagnosis method, the multimeter circuit is a multimeter. In B, the red probe of the multimeter is connected to the "+", "-", and "S" terminals of the bus terminal, respectively, and the black probe of the multimeter is connected to the ground on the field device side.

[0013] In one or more embodiments of the Foundation Fieldbus fault diagnosis method, the multimeter circuit is a multimeter. In step D, when the multimeter measures the connection between the "-" terminal of the terminal block and the grounding on the cabinet side, the positively charged probe of the multimeter is connected to the "-" terminal of the terminal block, and the negatively charged probe is connected to the grounding on the cabinet side; when the multimeter measures the connection between the "+" terminal of the terminal block and the grounding on the cabinet side, the negatively charged probe of the multimeter is connected to the "+" terminal of the terminal block, and the positively charged probe is connected to the grounding on the cabinet side.

[0014] According to another aspect of the present invention, a diagnostic circuit for a Foundation Fieldbus includes: a switch module, which is connected to the bus terminal of the network communication module on the field device side of the Foundation Fieldbus and the wiring terminal on the cabinet side of the Foundation Fieldbus, respectively, to control the disconnection or connection of the two; and a diagnostic module, including a multimeter circuit, including a resistance range, wherein the voltage range can be connected to the "+" terminal and the "-" terminal on one side of the wiring terminal, respectively, and connected to the ground on the cabinet side on the other side.

[0015] In one or more embodiments of the diagnostic circuit, the voltage level is connected in series with a first resistor on one side, the sum of the resistance of the voltage level and the resistance of the first resistor being greater than or equal to the ground resistance threshold specified by the Foundation Fieldbus.

[0016] In one or more embodiments of the diagnostic circuit, the Foundation fieldbus specifies a ground resistance threshold of 20 MΩ, and the sum of the resistance of the voltage level and the resistance of the first resistor is 21 MΩ to 101 MΩ.

[0017] In one or more embodiments of the diagnostic circuit, the multimeter circuit further includes a voltage range; the resistance range can be connected to each end of the bus terminal on one side and to ground on the field device side on the other side, and / or to each end of the wiring terminal on one side and to ground on the cabinet side on the other side. Attached Figure Description

[0018] The above and other features, properties, and advantages of the present invention will become more apparent from the following description taken in conjunction with the accompanying drawings and embodiments, in which the same reference numerals always denote the same features. It should be noted that these drawings are merely illustrative and are not drawn to scale, and should not be construed as limiting the scope of protection actually claimed by the present invention, wherein:

[0019] Figure 1 This is a schematic diagram of the structure of a Foundation Fieldbus according to an embodiment;

[0020] Figure 2 A flowchart illustrating a fault diagnosis method for Foundation Fieldbus according to one embodiment;

[0021] Figure 3 This is a schematic diagram of the structure for fault diagnosis of a Foundation Fieldbus according to an embodiment;

[0022] Figure 4 A flowchart of a fault diagnosis method for Foundation Fieldbus according to another embodiment;

[0023] Figure 5 This is a schematic diagram of the fault diagnosis structure of the Foundation Fieldbus according to another embodiment;

[0024] Figure 6 This is a schematic diagram of a diagnostic circuit for Foundation Fieldbus according to one embodiment.

[0025] Figure 7 This is a fault diagram of a Foundation Fieldbus.

[0026] Figure label:

[0027] 100 - Field device side, 200 - Cabinet side, 300 - Equipment;

[0028] 1-Network segment;

[0029] 2-Power supply card;

[0030] 3-Terminal blocks;

[0031] 4-Network communication module;

[0032] 5-RC terminator;

[0033] 6-Bus cable;

[0034] 7 - Multimeter circuit, 71 - Red probe, 72 - Black probe;

[0035] 8 - Resistance to ground;

[0036] 81 - Grounding on the field device side; 82 - Grounding on the cabinet side;

[0037] 90- Junction Box;

[0038] 9-Bus terminal;

[0039] 10-Branch terminal circuit;

[0040] 101 - First resistor, 102 - Resistance to ground;

[0041] 400 - Switch module, 500 - Diagnostic module. Detailed Implementation

[0042] Reference will now be made in detail to various embodiments of the invention, examples of which are shown in the accompanying drawings and described below. Although the invention will be described in conjunction with exemplary embodiments, it should be understood that this specification is not intended to limit the invention to those exemplary embodiments. Rather, the invention is intended to cover not only these exemplary embodiments, but also various alternatives, modifications, equivalents, and other embodiments that may be included within the spirit and scope of the invention as defined by the appended claims.

[0043] In the following description, the orientation or positional relationship indicated by terms such as "left", "right", "center", "longitudinal", "lateral", "inner", "outer" or other directional terms is based on the orientation or positional relationship shown in the accompanying drawings and is only for the convenience of describing the invention and simplifying the description, and is not intended to indicate or imply that the device or component referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention.

[0044] Furthermore, this application uses specific terms to describe its embodiments. For example, "an embodiment" and / or "one embodiment" refers to a particular feature, structure, or characteristic associated with at least one embodiment of this application. Therefore, it should be emphasized and noted that "an embodiment" or "one embodiment" mentioned twice or more in different locations in this specification do not necessarily refer to the same embodiment. In addition, certain features, structures, or characteristics in one or more embodiments of this application can be appropriately combined.

[0045] Flowcharts are used in this application to illustrate the operations performed by the system according to embodiments of this application. It should be understood that the preceding or following operations are not necessarily performed in exact order. Other operations may be added to these processes, or one or more operations may be removed from these processes.

[0046] refer to Figures 1 to 3 As shown, in one embodiment, the Foundation Fieldbus includes a field device side 100 and a cabinet side 200. The specific steps of the Foundation Fieldbus fault diagnosis method may include:

[0047] The bus terminal 9 of the network communication module 4 on the field device side 100 is kept connected to the power supply, and the wiring terminal 3 on the cabinet side 200 is kept connected to the power supply; the voltage range of the multimeter circuit 7 is connected to the "+" and "-" terminals of the wiring terminal 3 on one side, and to the ground 82 of the cabinet side 200 on the other side. If the obtained voltage value is greater than the reference voltage of the foundation fieldbus, then there is a fault.

[0048] The "Field Device Side 100" here refers to the side where the device 300 connected to the Foundation Fieldbus is located, such as... Figure 1 , Figure 2 , Figure 4 As shown, the field device side 100 also includes bus terminals 9 and branch terminal loops 10; while the "rack side 200" refers to the side where the power card 2 of the Foundation fieldbus that powers the equipment 300 is located, such as... Figure 1 , Figure 2 , Figure 4 As shown, the cabinet side 200 also includes wiring terminals 3, and the cabinet side 200 is generally a cabinet room.

[0049] The "multimeter circuit 7" mentioned here refers to a circuit constructed using the principle circuit of a commonly used electrical device, the "multimeter," which can measure resistance, current, and voltage.

[0050] The "reference voltage" here refers to the voltage range of the Foundation Fieldbus under normal conditions. The inventors discovered that even under normal Foundation Fieldbus conditions, due to factors such as disturbances and measurement accuracy limitations, the voltage range may still show a reading. Therefore, a voltage value greater than zero does not necessarily indicate a fault. For commonly used multimeters, the inventors found that the voltage reference value is 1VDC. That is, when a stable voltage above 1VDC is measured, regardless of the resistance value, it is considered a fault. Of course, it can be understood that the reference value may differ for different types of Foundation Fieldbuses, the operating environment, and different multimeter circuits. The specific reference value can be obtained through experimentation.

[0051] In some embodiments, multimeter circuit 7 is a multimeter, reference Figure 3 As shown, the specific steps for fault diagnosis of the Foundation fieldbus using a multimeter can be as follows:

[0052] like Figure 3As shown, the resistance 8 at the "+" and "-" terminals of fieldbus segment 1 in the theoretical design foundation is open-circuited. Therefore, when measuring the voltage between the "+" terminal and the ground 82 on the cabinet side, and the voltage between the "-" terminal and the ground 82 on the cabinet side, the voltage value is 0Vdc. However, assuming that the potential at the "-" terminal is connected to ground when the resistance 8 is present, measuring the voltage between the ground 82 on the cabinet side and the "+" terminal of terminal 3 is equivalent to measuring the voltage drop across the "+" and "-" terminals of terminal 3 caused by the resistance 8 at ground. Similarly, assuming that the potential at the "+" terminal is connected to ground when the resistance 8 is present, measuring the voltage between the ground 82 on the cabinet side and the "-" terminal of terminal 3 is equivalent to measuring the voltage drop across the "+" and "-" terminals of terminal 3 caused by the resistance 8 at ground. After measuring the supply voltage across the "+" and "-" terminals of terminal 3, the voltage between the "+" and "-" terminals of terminal 3 and the ground 82 on the cabinet side is then measured and compared. The larger the voltage between the "+" and "-" terminals and the grounding 82 on the cabinet side, and the closer it is to the supply voltage, the smaller the ground resistance 8 at the "+" and "-" terminals, which may indicate a short circuit to ground, meaning there is a fault in this circuit.

[0053] Although the Foundation's Fieldbus Engineering Technical Guidelines specify that a resistance to ground of ≥20MΩ at both the "+" and "-" terminals is within the normal range, the inventors discovered that when, for example... Figure 7 In the case of the fault shown, although the resistance to ground is ≥20MΩ, the actual circuit has a fault resistance of ≤20MΩ. Therefore, the inventors discovered that it is difficult to measure the resistance value while maintaining power supply, and fault diagnosis requires measurement using a voltage range. Furthermore, a reference voltage must first be obtained; if the measured voltage value is greater than the reference voltage, a fault is determined to exist.

[0054] The advantages of using the above embodiments are that they can be performed during the daily operation of the Foundation Fieldbus without power interruption, and step A can be performed periodically during daily operation. If a fault is detected in step A, the specific fault point can be identified.

[0055] The above embodiments employ online voltage measurement, eliminating the need to power off the network segment. Diagnostic measurements are performed using the voltage setting on a multimeter, allowing for regular monitoring of the Foundation fieldbus's operational health. This ensures normal online operation of the equipment while efficiently completing diagnostics. This significantly improves fault diagnosis efficiency and reduces costs, making the fault diagnosis process simple, fast, accurate, and efficient, and greatly enhancing the reliability of the Foundation fieldbus.

[0056] refer to Figure 4 as well as Figure 5 As shown, in some embodiments, when a fault is detected in the Foundation Fieldbus via A, the specific fault location can be identified through the following steps:

[0057] B. The bus terminal 9 of the network communication module 4 on the field device side 100 is disconnected, while the wiring terminal 3 on the cabinet side 200 remains connected and powered. The resistance setting of the multimeter circuit 7 is connected to each terminal of the bus terminal 9 on one side and to the ground 81 of the field device side 100 on the other side. If the obtained resistance value is not an open circuit resistance value, then the network communication module and branch circuit are faulty. Here, "branch circuit" refers to the collective term for all branch terminal circuits 10. The branch terminal circuits 10 of the network communication module 4 on the field device side 100 are disconnected one by one. If the obtained resistance value after disconnecting a certain branch terminal circuit 10 is an open circuit resistance value, then that branch terminal circuit 10 is diagnosed as faulty.

[0058] C. The bus terminal 9 of the network communication module 4 on the field device side 100 is disconnected, and the wiring terminal 3 on the cabinet side 200 is disconnected; the resistance setting of the multimeter circuit 7 is connected to each end of the bus terminal 9 on one side, and to the ground 81 of the field device side 100 on the other side.

[0059] D. The bus terminal 9 of the network communication module 4 on the field device side 100 is disconnected, while the wiring terminal 3 on the cabinet side 200 remains connected and powered; the resistance setting of the multimeter circuit 7 is connected to each end of the wiring terminal 3 on one side and to the ground 82 on the cabinet side 200 on the other side.

[0060] The "open-circuit resistance" here refers to an infinite resistance measured in the multimeter circuit. It's important to note the difference between "open-circuit resistance" and the ground resistance threshold specified by the Foundation Fieldbus. For example, the Foundation Fieldbus typically specifies a ground resistance threshold of 20MΩ, but this is not an open-circuit resistance; an open-circuit resistance is infinite. The multimeter circuit described here, similar to those described above, refers to a circuit constructed using the basic principle of a common electrical device, the multimeter, capable of measuring resistance, current, and voltage. For example, multimeter circuit 7 here could be a multimeter or a megohmmeter.

[0061] In some embodiments, multimeter circuit 7 is a multimeter, reference Figure 5 As shown, the specific steps for fault diagnosis of the Foundation fieldbus using a multimeter can be as follows:

[0062] B. Disconnect the bus terminal 9 of the network communication module 4 from the junction box 90 on the field device side 100 to de-energize network segment 1. Using the resistance setting of a multimeter, connect the red probe 71 of the multimeter to the "+", "-", and "s" terminals of the bus terminal 9, respectively, and connect the black probe 72 of the multimeter to the ground 81 on the field device side 100. Measure the resistance to ground 8 between the "+" terminal of the bus terminal 9 and the ground 81 on the field device side, the "-" terminal and the ground 81 on the field device side, and the "s" terminal and the ground 81 on the field device side, respectively. The resistance values ​​should all be infinite, indicating normal operation. If the measured resistance value is not infinite, it indicates a short circuit to ground. In this case, the measured resistance to ground 8 is an abnormal resistance to ground due to a fault in network segment 1, requiring further inspection. While using a multimeter to measure the fault resistance to ground 8, disconnect the branch terminal circuits 10 on the network communication module 4 one by one until the resistance to ground 8 becomes infinite after disconnecting a certain branch terminal circuit 10. This indicates that there is a short circuit to ground in this branch circuit, affecting the entire network segment 1. Then, the individual branch circuit can be specifically investigated. This greatly simplifies the entire fault investigation process, accurately locates the fault point, and is simple and easy to operate.

[0063] C. When all branch terminal circuits 10 of the network communication module 4 are normal, it is necessary to further measure the ground resistance 8 of the bus circuit. At this time, it is necessary to go to the cabinet room, i.e., the cabinet side 200, disconnect the wiring terminal 3, and measure the ground resistance 8 between the "+" terminal of the bus terminal 9 on the field device side 100 and the ground 81 on the field device side, the "-" terminal and the ground 81 on the field device side, and the "s" terminal and the ground 81 on the field device side. If the measured resistance value is infinite, it indicates that the bus circuit is normal; otherwise, it indicates that there is a fault in the bus, which needs to be eliminated.

[0064] D. If the measurement of bus terminal 9 on the field device side 100 is still normal, then it is necessary to measure the resistance on the cabinet side 200. Since the circuit on the cabinet side 200 is energized, the multimeter probes will also be energized when measuring in resistance mode. When measuring the connection between the "-" terminal of terminal 3 and the ground 82 on the cabinet side 200, ensure that the positively charged probe of the multimeter is connected to the "-" terminal of terminal 3, and the negatively charged probe is connected to the ground 82 on the cabinet side. When measuring the connection between the "+" terminal of terminal 3 and the ground 82 on the cabinet side, connect the negatively charged probe of the multimeter to the "+" terminal of terminal 3, and the positively charged probe to the ground 82 on the cabinet side. At this time, the resistance between the "+" terminal and ground and the "-" terminal and ground of terminal 3 can be measured under energized conditions. An infinite resistance value is normal. Since the bus circuit is grounded at a single point on the power card 2, the resistance value of the "S" terminal of the terminal block 3 and the grounding 82 on the rack side should be ≤2Ω when measuring the resistance. If the rack side circuit is found to be abnormal, the rack side circuit needs to be checked or the power card 2 needs to be replaced.

[0065] The above embodiments employ an offline resistance measurement method. By disconnecting the power to the network segment and using the resistance setting of a multimeter circuit for diagnostic measurement, the fault point can be quickly and accurately located when a fault occurs in the network segment. This simplifies the fault diagnosis process of the Foundation Fieldbus, greatly improves fault diagnosis efficiency, and saves fault diagnosis costs.

[0066] refer to Figure 3 As shown, in some embodiments, step A of the Foundation Fieldbus fault diagnosis method may further include connecting a first resistor 101 in series on one side of the voltage range of the multimeter circuit 7. The sum of the resistance of the voltage range and the resistance of the first resistor 101 is greater than or equal to the ground resistance threshold specified by the Foundation Fieldbus. This setting ensures the safe use of the multimeter circuit and improves the reliability of fault diagnosis. The principle is that when the multimeter circuit is a multimeter, after the multimeter is set to the voltage range, the resistance of the multimeter is about 11MΩ. When measuring the voltage between the "+" and "-" terminals of the wiring terminal 3 and the grounding 82 on the cabinet side, it does not meet the Foundation Fieldbus segment resistance requirement of ≥20MΩ. There is a potential risk that interference signals may enter the Foundation Fieldbus through the measurement circuit during measurement, affecting normal communication. Therefore, a resistor of ≥10MΩ is connected in series in the multimeter probes to transform it into a voltage measuring meter of ≥20MΩ, which meets the measurement requirements and ensures the safe and reliable fault diagnosis work.

[0067] This setup ensures safe and reliable fault diagnosis while improving diagnostic accuracy. The principle is that, according to laboratory tests and analysis, the resistance of the multimeter voltage range circuit is approximately 11MΩ (the resistance value varies depending on the multimeter model and brand). The multimeter probes can be connected in series with resistors ranging from 10MΩ to 90MΩ, forming a multimeter circuit resistance of 21MΩ to 101MΩ. Connecting a resistor less than 10MΩ in series with the multimeter is unacceptable, while a resistor greater than 90MΩ will result in an extremely low voltage drop, potentially below the reference voltage, making it impossible to determine the voltage value corresponding to the foundation fieldbus resistance to ground, thus rendering the fault diagnosis invalid. To avoid excessively low voltage drop, the resistance value of the first circuit 101 in series should be as large as possible. This helps to avoid interference from unexpected situations such as lightning strikes, making the diagnostic results more accurate and reliable.

[0068] Following the aforementioned fault diagnosis method, although the above method uses a multimeter for manual diagnosis, it can also be implemented using semi-automatic or fully automatic diagnostic circuits. Therefore, this application also provides a diagnostic circuit for Foundation Fieldbus, integrating the principle circuit of the fault diagnosis method (multimeter circuit 7) into the diagnostic module. Its specific structure can be referenced... Figures 1 to 6As shown, the system includes a switch module 400 and a diagnostic module 500. The switch module 400 is connected to the bus terminal 9 of the network communication module 4 on the field device side 100 of the Foundation Fieldbus and the terminal block 3 on the cabinet side 200 of the Foundation Fieldbus, respectively, to control the disconnection or connection of the two. The diagnostic module 500 includes a multimeter circuit 7, including resistance and / or voltage ranges. The resistance range can be connected to each terminal of the bus terminal 9 on one side and to the ground 81 of the field device side 100 on the other side, and / or to each terminal of the terminal block 3 on one side and to the ground 82 of the cabinet side 200 on the other side. The voltage range can be connected to the "+" and "-" terminals of the terminal block 3 on one side and to the ground 82 of the cabinet side 200 on the other side.

[0069] The advantages of this setup are that it enables semi-automatic or fully automatic fault diagnosis of the Foundation Fieldbus. Using online voltage measurement, the network segment can be diagnosed without powering off; a multimeter's voltage setting is used for diagnostic measurements. This allows for regular monitoring of the Foundation Fieldbus's operational health, ensuring normal online operation while efficiently completing diagnostics. Using offline resistance measurement, the network segment is powered off, and a multimeter's resistance setting is used for diagnostic measurements. When a fault occurs in the network segment, the fault point can be quickly and accurately located, simplifying the Foundation Fieldbus fault diagnosis process, significantly improving efficiency, and saving costs. Furthermore, if an online voltage measurement method diagnoses a fault in the Foundation Fieldbus, the offline resistance method can be used to quickly locate the specific fault point for repair. This makes the fault diagnosis process simple, fast, accurate, and efficient, greatly improving the operational reliability of the Foundation Fieldbus.

[0070] In some embodiments, a first resistor 101 is connected in series on one side of the voltage level, and the sum of the resistance of the voltage level and the resistance of the first resistor 101 is greater than or equal to the ground resistance threshold specified by the Foundation Fieldbus. This configuration ensures the safe and reliable operation of the diagnostic circuit.

[0071] In some embodiments, as described above, the ground resistance threshold specified by the Foundation Fieldbus is 20MΩ, and the sum of the resistance value of the voltage range and the resistance value of the first resistor 101 is 21MΩ to 101MΩ, so as to ensure the safety and reliability of fault diagnosis while improving the diagnostic effect.

[0072] The following is an example of successfully implementing rapid and accurate fault diagnosis of the Foundation Fieldbus using the technical solution of this application:

[0073] (1) Fault finding using offline resistance measurement method: In the APU unit, a network segment frequently experienced network alarms, instrument and control valve failures, which repeatedly affected process operation. According to the diagnostic method of this invention, a short circuit between the "+" pole and ground of a pressure transmitter was successfully identified, affecting the instruments in the entire network segment.

[0074] (2) Fault finding using offline resistance measurement method: In an ethylene separation unit, all instruments on one network segment experienced alarm faults. Using the diagnostic method of this invention, the fault was accurately located to a temperature transmitter on a disused device that lacked maintenance water ingress; the positive and negative terminals of a cable were wrapped with tape and stuffed into the cable tray. These two problems in one network segment had a significant impact on the entire network segment.

[0075] (3) Network segment detection using online voltage measurement method: For the styrene plant, all 177 FF bus network segments were tested. 163 network segments met the requirements, while 14 network segments had short circuits to ground. The 14 problematic network segments were then checked one by one using offline resistance measurement method to ensure reliability.

[0076] (4) Network segment detection using online voltage measurement method: In the butadiene unit, all 66 FF bus network segments of the unit were tested. 65 network segments met the requirements, and 1 network segment had a short circuit to ground. The 1 network segment with potential problems was checked one by one using offline resistance measurement method to ensure reliability.

[0077] While the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the invention. Any variations and modifications can be made by those skilled in the art without departing from the spirit and scope of the invention. Therefore, any modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention, without departing from the scope of the invention, fall within the protection scope defined by the claims of the present invention.

Claims

1. A fault diagnosis method for a Foundation Fieldbus, the Foundation Fieldbus comprising a field device side (100) and a cabinet side (200), characterized in that, The fault diagnosis method includes: A. The bus terminal (9) of the network communication module (4) on the field device side (100) is kept connected and powered, and the wiring terminal (3) on the cabinet side (200) is kept connected and powered; the voltage range of the multimeter circuit (7) is connected to the "+" terminal and "-" terminal of the wiring terminal (3) on one side, and to the ground (82) of the cabinet side (200) on the other side, so as to measure the voltage value between the "+" terminal and the ground (82) of the cabinet side (200), and the voltage value between the "-" terminal and the ground (82) of the cabinet side (200). If one of the above two voltage values ​​is greater than the reference voltage of the Foundation Fieldbus, or if both voltage values ​​are greater than the reference voltage of the Foundation Fieldbus, then it is a fault. The voltage range of the multimeter circuit (7) is connected in series with a first resistor (101) on one side. The sum of the resistance value of the voltage range and the resistance value of the first resistor (101) is greater than or equal to the ground resistance threshold specified by the Foundation Fieldbus. The fault diagnosis method further includes: B. If A is determined to be a fault, the bus terminal (9) of the network communication module (4) on the field device side (100) is disconnected, and the wiring terminal (3) on the cabinet side (200) remains connected to the power supply; the resistance range of the multimeter circuit (7) is connected to each end of the bus terminal (9) on one side and to the ground (81) of the field device side (100) on the other side; if the obtained resistance value is not an open circuit resistance value, then the network communication module and the branch circuit are faulty, and the branch terminal circuit (10) of the network communication module (4) on the field device side (100) is disconnected one by one. If the resistance value obtained after a certain branch terminal circuit (10) is disconnected is an open circuit resistance value, then the branch terminal circuit (10) is diagnosed as a fault. C. The bus terminal (9) of the network communication module (4) on the field device side (100) is disconnected, and the wiring terminal (3) on the cabinet side (200) is disconnected; the resistance range of the multimeter circuit (7) is connected to each end of the bus terminal (9) on one side and to the ground (81) of the field device side (100) on the other side. D. The bus terminal (9) of the network communication module (4) on the field device side (100) is disconnected, while the wiring terminal (3) on the cabinet side (200) remains connected to the power supply; the resistance range of the multimeter circuit (7) is connected to each end of the wiring terminal (3) on one side and to the ground (82) of the cabinet side (200) on the other side.

2. The fault diagnosis method for Foundation Fieldbus as described in claim 1, characterized in that, The ground resistance threshold specified by the Foundation Fieldbus is 20MΩ, and the sum of the resistance value of the voltage level and the resistance value of the first resistor (101) is 21MΩ to 101MΩ.

3. The fault diagnosis method for Foundation Fieldbus as described in claim 1, characterized in that, The multimeter circuit (7) is a multimeter. In B, the red probe of the multimeter is connected to the "+", "-", and "s" terminals of the bus terminal (9), respectively, and the black probe of the multimeter is connected to the ground (81) of the field device side (100).

4. The fault diagnosis method for Foundation Fieldbus as described in claim 1, characterized in that, The multimeter circuit (7) is a multimeter. In D, when the multimeter measures the "-" terminal of the terminal (3) and the ground (82) of the cabinet side (200), the positively charged probe of the multimeter is connected to the "-" terminal of the terminal (3), and the negatively charged probe is connected to the ground (82) of the cabinet side (200). When the multimeter measures the "+" terminal of the terminal (3) and the ground (82) of the cabinet side (200), the negatively charged probe of the multimeter is connected to the "+" terminal of the terminal (3), and the positively charged probe is connected to the ground (82) of the cabinet side (200).

5. A diagnostic circuit for Foundation Fieldbus, characterized in that, Capable of being used in the diagnostic method as described in any one of claims 1-4, comprising: The switch module is connected to the bus terminal (9) of the network communication module (4) on the field device side (100) of the Foundation Fieldbus and the wiring terminal (3) on the cabinet side (200) of the Foundation Fieldbus, respectively, to control the disconnection or connection of the two. The diagnostic module includes a multimeter circuit (7) with voltage ranges; The voltage level can be connected to the "+" terminal and "-" terminal of the wiring terminal (3) on one side, and to the ground (82) of the cabinet side (200) on the other side; The diagnostic circuit is configured to measure the voltage between the "+" terminal and the ground (82) of the cabinet side (200), and to measure the voltage between the "-" terminal and the ground (82) of the cabinet side (200). If one of the two voltage values ​​is greater than the reference voltage of the Foundation Fieldbus, or if both voltage values ​​are greater than the reference voltage of the Foundation Fieldbus, then a fault is detected. The voltage level is connected in series with a first resistor (101) on one side. The sum of the resistance of the voltage level and the resistance of the first resistor (101) is greater than or equal to the ground resistance threshold specified by the Foundation Fieldbus.

6. The diagnostic circuit as described in claim 5, characterized in that, The ground resistance threshold specified by the Foundation Fieldbus is 20MΩ, and the sum of the resistance value of the voltage level and the resistance value of the first resistor (101) is 21MΩ to 101MΩ.

7. The diagnostic circuit as described in claim 5, characterized in that, The multimeter circuit (7) also includes a resistance range, which can be connected to each end of the bus terminal (9) on one side and to the ground (81) of the field device side (100) on the other side, and / or to each end of the wiring terminal (3) on one side and to the ground (82) of the cabinet side (200) on the other side.

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