Remote I / O station

Abstract

To provide a remote I / O station that determines the presence or absence of an abnormality in a plant by reducing a load on a PLC.SOLUTION: An remote I / O station includes: a communication interface that obtains a plurality of control signals from a communication network connected to a PLC and to a first device; a local communication interface that obtains another control signal from a local communication network; a monitoring unit that determines the presence or absence of an abnormality in a plant, based on a determination criterion set according to an item to be diagnosed and based on the control signal; and a storage unit that stores the signal when the presence of the abnormality is determined.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] An embodiment of the present invention relates to a remote I / O station for use in a plant control system. [Background technology]

[0002] In steel plants and similar, the operation of various devices and equipment (hereafter referred to as "devices") throughout the plant is controlled while monitoring their status. This ensures efficient production while ensuring safety. Programmable logic controllers (hereafter referred to as "PLCs") are primarily used to control and monitor devices. A large number of control targets and devices to be monitored are connected to a PLC, and managing all of that information requires a complex, large-scale program with many functions.

[0003] For example, in Patent Document 1, a large amount of plant data is collected, and AI (artificial intelligence) is used to extract change points in the collected plant data, thereby judging whether or not there is an abnormality in the plant. However, in this technology, the AI ​​only extracts change points, and the user, a plant monitor, needs to judge whether or not there is an abnormality based on the results output by the system.

[0004] Edge computing is becoming increasingly important as it simplifies PLC design while reducing the load on the PLC by having end devices execute some of the control targets among the large amounts of plant data. It is hoped that the application of edge computing technology will reduce the communication load on the PLC and reduce the scale of the PLC's control program. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 5868784 Summary of the Invention [Problem to be solved by the invention]

[0006] In view of the above circumstances, an object of an embodiment of the present invention is to provide a remote I / O station that determines the presence or absence of an abnormality in a plant while reducing the load on a PLC. [Means for solving the problem]

[0007] An embodiment of the present invention includes a communication interface that acquires from the communication network a first control signal output to the communication network by a first device that executes a first process related to a product, and a second control signal output to the communication network by a control device that controls the operation of the first device, a local communication interface that acquires a third control signal generated by a second process related to the product via the local communication network, a monitoring unit that has predetermined judgment criteria for an item to be diagnosed and diagnoses the presence or absence of an abnormality in the first process or the second process based on the judgment criteria and at least one of the first control signal, the second control signal, and the third control signal, and a memory unit that stores a signal that has an abnormality among the first control signal, the second control signal, and the third control signal at the time when the abnormality is diagnosed. Effect of the Invention

[0008] According to the embodiment, a remote I / O station is provided that determines whether or not there is an abnormality in a plant while reducing the load on a PLC. [Brief description of the drawings]

[0009] [Figure 1] FIG. 2 is a schematic block diagram illustrating a remote I / O station according to an embodiment. [Diagram 2] 10 is a schematic flowchart illustrating an example of an operation of a remote I / O station according to an embodiment. [Diagram 3] 3(a) to 3(c) are graphs for explaining the operation of the remote I / O station according to the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an embodiment will be described with reference to the drawings. The drawings are schematic or conceptual, and the relationship between the thickness and width of each part, the size ratio between parts, etc. are not necessarily the same as in reality. Even when the same part is shown, the dimensions and ratios of each part may be different depending on the drawing. In this specification and each drawing, elements similar to those described above with reference to the previous drawings are given the same reference numerals and detailed descriptions thereof will be omitted as appropriate.

[0011] FIG. 1 is a schematic block diagram illustrating a remote I / O station according to an embodiment. 1 shows the configuration of a plant control system to which a remote I / O station 121 is applied, together with the configuration of the remote I / O station 121. First, the configuration of the plant control system will be described.

[0012] As shown in Fig. 1, the plant control system includes a programmable logic controller (PLC) 1, a drive device 21, and a remote I / O station 121. The PLC 1, the drive device 21, and the remote I / O station 121 are communicatively connected to a communication network 4. The PLC 1, the drive device 21, and the remote I / O station 121 communicate with each other via the communication network 4, and exchange various signals and the like. In addition to those shown in the figure, other drive devices, remote I / O stations, and the like may also be connected to the communication network 4. The communication network 4 is, for example, a control network.

[0013] The PLC (control device) 1 includes a CPU 2 and a remote I / O interface 3. The CPU 2 is connected to a communication network 4 via the remote I / O interface 3. The PLC 1 has a memory (not shown) and operates according to a control program loaded on the memory, and exchanges various signals with the drive device 21 and the remote I / O station 121.

[0014] In the specific example of FIG. 1, the PLC 1 outputs a speed command for controlling the speed of the motor 33 to the communication network 4 as a REF signal.

[0015] The drive device (first device) 21 includes a communication interface 22 and a control unit 25. Although not shown, the control unit 25 is connected to a drive circuit, and is connected to a motor 33 via the drive circuit.

[0016] The drive device 21 acquires the REF signal 23 output to the communication network 4 via the communication interface 22. The control unit 25 also receives the FBK signal 32 as a speed feedback signal from a speed sensor (not shown) provided on the motor 33. The control unit 25 calculates a control output 31 based on the REF signal 23 and the FBK signal 32, and outputs the control output 31 to the drive circuit. The drive circuit drives the motor 33 based on the control output 31.

[0017] The control unit 25 outputs the FBK signal 24 received from the speed sensor to the communication network 4 via the communication interface 22 .

[0018] The remote I / O station 121 includes a communication interface 122, a drive control monitor unit 125, and a pulse input unit 126. The remote I / O station 121 may include a memory unit 127. Preferably, the remote I / O station 121 further includes an error display lamp (alarm means) 128.

[0019] The communication interface 122 acquires signals input / output to / from the drive device 21 from the communication network 4. The signals to be acquired are set in advance. In the specific example of Fig. 1, the communication interface 122 is set to acquire a REF signal and a FBK signal 123 of the drive device 21.

[0020] The drive control monitor (monitoring unit) 125 is connected to an I / O module managed by the remote I / O station 121 via a local communication interface. The I / O module includes various sensors such as a speed sensor and a temperature sensor, and various actuators. In the specific example of FIG. 1, the drive control monitor 125 is connected to a resolver 131 via a pulse input unit 126 as a local communication interface. The drive control monitor 125 sequentially monitors the REF signal and the FBK signal 123, and the number of pulses output by the resolver 131.

[0021] The drive control monitoring unit 125 diagnoses whether the drive device 21 is operating properly by applying a preset judgment criterion to the REF signal, the FBK signal 123, and the number of pulses output by the resolver 131. The drive control monitoring unit 125 stores the diagnosis result 124 in the memory unit 127. The memory unit 127 may be provided inside the remote I / O station 121, or may be provided in an external storage device, data server, or the like via the communication interface 122 as in the specific example of FIG.

[0022] By appropriately configuring the drive control monitoring unit 125, it is possible to diagnose the operation of the drive device 21 during steady-state operation, as well as to diagnose whether or not there is an abnormality when a preset event occurs, as described below in relation to Figures 2 and 3.

[0023] When the remote I / O station 121 according to the embodiment judges an abnormality in a preset operation diagnosis during normal operation or when an event occurs, it stores at least data on the time when the signal was judged to be abnormal in the memory unit 127. Preferably, the remote I / O station 121 stores signals for a predetermined period before and after the time when the abnormality was judged to be abnormal in the memory unit 127. The periods before and after the time when the abnormality was judged to be abnormal are set beforehand, and may be the same period before and after, or may be different periods. Either of the periods before and after may be set to zero. Furthermore, these periods may be set for each signal or operation to be diagnosed.

[0024] When an abnormality is determined in an operation diagnosis during normal operation or when an event occurs, the remote I / O station 121 according to the embodiment turns on an error display lamp 128. By turning on the error display lamp 128, the occurrence of an abnormality can be easily recognized visually. As long as an operator or the like who visually recognizes the remote I / O station 121 can recognize the occurrence of an abnormality, other display means may be used instead of a lamp, or the abnormality may be notified by other means such as a sound, or a combination of these multiple means that directly affect human senses may be used.

[0025] The operation and effects of the remote I / O station 121 according to the embodiment will be described. FIG. 2 is a schematic flowchart illustrating an example of an operation of the remote I / O station according to the embodiment. 2, as a specific example, data exchange in a rolling process of a steel plant is shown in a flow chart. That is, the drive device 21 inputs a speed feedback signal (speed FBK) from a speed sensor provided on the driving roll of the rolling mill. The drive device 21 outputs the speed FBK to the communication network 4.

[0026] The PLC 1 outputs a speed reference (speed REF) to the communication network 4. The drive device 21 receives the speed REF via the communication network 4. The drive device 21 controls the speed of the drive roll based on the speed FBK and the speed REF.

[0027] A resolver 131 provided on a table roll or the like that transports the rolled material outputs a pulse with a frequency corresponding to the transport speed of the rolled material. The remote I / O station 121 inputs the pulses output by the resolver 131 to a pulse input unit 126, counts the input pulses, and calculates the transport speed of the rolled material (steel plate speed).

[0028] Under the above-mentioned circumstances, in step S1, the drive control monitor unit 125 sequentially inputs each data of the speed REF, the speed FBK and the steel plate speed.

[0029] In step S2, the drive control monitor 125 sequentially executes an event extraction process. In the event extraction process, the drive control monitor 125 sequentially judges whether the input data satisfies a preset condition, and judges that an event has been extracted if the condition is satisfied.

[0030] In step S3, the drive control monitor 125 executes a routine diagnosis process on the input data. In the routine diagnosis process, the drive control monitor 125 judges whether the input data is abnormal based on whether the input data satisfies preset conditions for routine diagnosis. If the input data is judged to be abnormal in the routine diagnosis process, the drive control monitor 125 transitions the process to step S5. If the input data is judged to be normal in the routine diagnosis process, the drive control monitor 125 ends the process.

[0031] In step S4, the drive control monitoring unit 125 executes an event diagnosis process for the input data. In the event diagnosis process, the drive control monitoring unit 125 determines whether or not an abnormality exists based on whether or not a preset condition related to event diagnosis is satisfied. If the input data is determined to be abnormal in the event diagnosis process, the drive control monitoring unit 125 transitions the process to step S5. If the input data is determined to be normal in the event diagnosis process, the drive control monitoring unit 125 ends the process.

[0032] In step S5, the drive control monitoring unit 125 stores data determined to be abnormal in the steady diagnosis process in the memory unit 127. The drive control monitoring unit 125 also stores data determined to be abnormal in the event diagnosis process in the memory unit 127.

[0033] For example, the memory unit 127 sequentially stores data sequentially input to the drive control monitor unit 125. In the steady-state diagnostic process, the drive control monitor unit 125 attaches a label to the time series data for the period before and after the time when an abnormality is determined, and stores the data as a diagnostic result. The label is, for example, an identification number of the data in which an abnormality is detected, in this example, the speed REF signal of the drive device 21, and is associated with the diagnosis time. After storing the labeled time series data in the memory unit 127 after an abnormality is determined, the data before the diagnosis time may be deleted, or the data may be transferred and stored in another area of ​​the memory unit 127 or another storage device.

[0034] Similarly, when an abnormality is determined in the event diagnosis process, for example, the drive control monitor 125 attaches a label to the time series data before and after the time when the abnormality is determined, and stores the label as a diagnosis result.

[0035] In step S6, the drive control monitoring unit 125 causes the memory unit 127 to retrieve data determined to be abnormal and output the data to the PLC 1 via the communication network 4. The timing at which the drive control monitoring unit 125 outputs data determined to be abnormal is set in advance. For example, the drive control monitoring unit 125 accumulates data for one operating day of the plant in the memory unit 127 and outputs the data collectively to the PLC 1 after the operation ends. Alternatively, the drive control monitoring unit 125 may output the data to the PLC 1 every time an abnormality is detected, or may determine a rank of the severity of the abnormality in advance, and output the data immediately if the abnormality is highly serious and output the data after the operation ends in other cases.

[0036] 3(a) to 3(c) are graphs for explaining the operation of the remote I / O station according to the embodiment. FIG. 3(a) shows an example of steady-state diagnostic processing in which the presence or absence of an abnormality is determined based on data input and output by the drive device 21. FIG. 3(b) shows an example of the event diagnosis process in which the presence or absence of an abnormality is determined based on data input and output by the drive device 21. FIG. 3(c) shows an example of steady-state diagnostic processing in which the presence or absence of an abnormality is determined based on data input by the drive device 21 and data output by devices other than the drive device 21.

[0037] As shown in Fig. 3(a), the drive control monitor 125 sequentially calculates the deviation between the speed REF output by the drive device 21 and the speed FBK output by the PLC 1 and input by the drive device 21. A deviation standard is set in the drive control monitor 125 in advance. The drive control monitor 125 compares the calculated deviation with the deviation standard, and stores the time when the deviation becomes equal to or greater than the deviation standard. The drive control monitor 125 labels the time series data of the speed REF and the speed FBK for the period before and after the stored time, and stores the data in the memory unit 127.

[0038] As shown in Fig. 3(b), conditions for event detection are preset in the drive control monitor 125. Specifically, the drive control monitor 125 sequentially monitors the speed REF and the speed FBK, and detects a stop event of the motor 33 when at least one of the speed REF and the speed FBK is in a deceleration state and falls below a predetermined stop speed. After that, the drive control monitor 125 sequentially calculates the deviation between the speed REF output by the drive device 21 and the speed FBK output by the PLC 1 and input by the drive device 21.

[0039] When the event diagnosis process is started, in this specific example, the deviation between the speed REF and the speed FBK is calculated sequentially. The drive control monitor 125 compares the calculated deviation with a preset deviation standard, and stores the time when the calculated deviation becomes equal to or greater than the deviation standard in the memory unit 127. The drive control monitor 125 labels the time series data of the speed REF and the speed FBK for the period before and after the stored time, and stores the data in the memory unit 127.

[0040] As shown in FIG. 3(c), the drive control monitoring unit 125 sequentially monitors the speed FBK output by the drive device 21, counts the pulses output by the resolver 131, and sequentially calculates the steel plate speed. The drive control monitoring unit 125 sequentially calculates the deviation between the speed FBK and the steel plate speed. A deviation standard is set in the drive control monitoring unit 125 in advance. The drive control monitoring unit 125 compares the calculated deviation with the deviation standard, and stores the time when the deviation becomes equal to or greater than the deviation standard. The drive control monitoring unit 125 attaches a label to the time series data of the speed FBK and the steel plate speed for the period before and after the stored time, and stores the data in the memory unit 127.

[0041] By appropriately setting the signals acquired by the remote I / O station 121 and the criteria for judgment, the remote I / O station 121 can diagnose the presence or absence of abnormalities in the operating conditions of devices, etc., without the PLC 1 having to collect and judge all signals. The items to be diagnosed are not limited to those described above, and can be diagnosed on any signal that the remote I / O station 121 can directly acquire and any signal that can be acquired from the communication network 4. Therefore, it is possible to reliably perform a diagnosis of the operation of the plant without increasing the communication burden for signal collection by the PLC 1, the scale of the program for processing the collected signals, etc.

[0042] In the above, the determination of the presence or absence of various abnormalities in the speed control of a motor in a steel plant has been specifically described, but as long as the signals collected by the remote I / O station and the determination criteria can be appropriately set, the application is not limited to the above-mentioned specific example. For example, it is of course possible to monitor environmental parameters such as temperature and humidity in each process of a plant other than a steel plant, or the surface temperature of a product, and determine the presence or absence of abnormalities.

[0043] In this way, a remote I / O station that reduces the load on the PLC and determines whether or not there are any abnormalities in the plant can be realized.

[0044] Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and spirit of the invention, and are included in the scope of the invention and its equivalents described in the claims. [Explanation of symbols]

[0045] 1...PLC, 4...communication network, 21...drive device, 33...motor, 121...remote I / O station, 125...drive control monitoring unit, 127...memory unit, 131...resolver

Claims

1. a communication interface that acquires, from the communication network, a first control signal that is output to the communication network by a first device that executes a first process related to a product, and a second control signal that is output to the communication network by a control device that controls an operation of the first device; a local communication interface for receiving, via a local communication network, a third control signal generated by a second process associated with the product; a monitoring unit having a predetermined judgment criterion for an item to be diagnosed, and diagnosing the presence or absence of an abnormality in the first process or the second process based on the judgment criterion and at least one of the first control signal, the second control signal, and the third control signal; a storage unit that stores one of the first control signal, the second control signal, and the third control signal at a time when the abnormality is diagnosed; A remote I / O station equipped with

2. the first process includes controlling a speed of a motor; The first control signal includes data of an actual measured speed value of the motor, the second control signal includes data of a speed command value of the motor; 2. The remote I / O station according to claim 1, wherein the monitoring unit diagnoses whether or not there is an abnormality in the speed control of the motor based on the deviation between the actual speed measurement value and the speed command value and on the judgment criterion.

3. the second process includes a transport control of the product; the third control signal includes data on a conveying speed of the product; 3. The remote I / O station according to claim 2, wherein the monitoring unit diagnoses the presence or absence of an abnormality in the transportation of the product based on the deviation between the actual speed measurement value and the transportation speed and on the judgment criterion.

4. 2. The remote I / O station according to claim 1, further comprising an alarm means for indicating an abnormality when said monitoring section diagnoses an abnormality in said first process or said second process.

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