JP3884275B2 - Plant control system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a plant control system used in a general industrial plant, and more particularly to an abnormality diagnosis technique for a human interface.
[0002]
[Prior art]
In a plant control system used in a general industrial plant, a plurality of general-purpose programmable controllers (hereinafter may be abbreviated as PLC as appropriate) and a plurality of general-purpose human interfaces (hereinafter, abbreviated as HMI as appropriate). ) On the transmission line, and various data can be transmitted between the general-purpose PLC and the general-purpose HMI. Therefore, the operator can control the plant equipment by operating these general-purpose HMIs. In addition, the HMI in such a plant control system usually has an abnormality diagnosis function using transmission / reception of signals with the PLC side.
[0003]
FIG. 3 is a block diagram showing a schematic configuration of a conventional plant control system provided with an HMI having such an abnormality diagnosis function. In this figure, HMI1 to HMI5 are connected on the transmission line L, and PLC1 to PLC5 are connected. HMI 1 to HMI 5 have diagnostic signal transmitters A 1 to A 5 , respectively. Among PLC1 to PLC5, PLC1 is called “representative PLC”, and only this PLC1 has a diagnostic means C1.
[0004]
Next, the operation of FIG. 3 will be described. First, the operator in charge of HMI1 performs a predetermined operation to activate HMI1. The diagnosis operation for HMI1 described below is automatically performed at a preset interval during operation of HMI1. When the HMI1 is activated, the diagnostic signal transmitter A1 transmits the diagnostic signal s1 to the PLC1 via the transmission line L at a predetermined interval. As the diagnostic signal transmission unit A1, for example, a counter transmission unit that is incremented or decremented at a predetermined interval can be used.
[0005]
In PLC1, the diagnostic means C1 inputs this diagnostic signal s1, performs abnormality diagnosis for HMI1, and outputs a diagnostic result signal d1. The diagnosis result signal d1 is transmitted not only to the HMI1 to be diagnosed but also to other HMI2 to HMI5 via the transmission line L, and the diagnosis result is displayed on the screen. Therefore, even if an abnormality occurs in the HMI1 and the contents of the diagnostic result signal d1 notifying that the abnormality is not displayed on the screen of the HMI1, each operator in charge of the HMI2 to HMI5 notices the abnormality of the HMI1 and is appropriate. Measures can be taken.
[0006]
The abnormality diagnosis process described above relates to the HMI1, but the abnormality diagnosis process is performed in exactly the same manner for the HMI2 to HMI5. The communication method between the PLC 1 and the HMI 1 to HMI 5 is mainly the polling communication method. As described above, each abnormality diagnosis for the HMI1 to HMI5 is performed using the function of the PLC1. Generally, the hardware configuration is considered to be more robust than the HMI and hard to break down in the PLC. This is because it is considered that the abnormality diagnosis using this function can improve the reliability as compared with the abnormality diagnosis using only the HMI function.
[0007]
[Problems to be solved by the invention]
As described above, by using the function of PLC1, higher reliability can be obtained than when abnormality diagnosis is performed with HMI alone. However, even though PLC 1 is more robust than HMI 1 to HMI 5 in terms of hardware, it does not fail at all, and naturally it sometimes fails. Then, when a failure occurs in PLC1, until the failure is recovered, abnormality diagnosis for HMI1 to HMI5 is not performed, or erroneous abnormality diagnosis is performed. In addition, even if a failure does not occur in PLC1, there is a case where the operation of PLC1 must be stopped artificially for the convenience of plant operation. In such a case, the operation of PLC1 is resumed. During this time, an abnormality diagnosis for HMI1 to HMI5 is not performed.
[0008]
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a plant control system that can always perform an abnormality diagnosis for HMI and improve the reliability of the entire system.
[0009]
[Means for Solving the Problems]
As means for solving the above-mentioned problems, the invention according to claim 1 is characterized in that a plurality of programmable controllers and a plurality of human interfaces are connected on a transmission line, and diagnosis is performed from a human interface to be diagnosed. In the plant control system, the signal is transmitted to the programmable controller side, and the programmable controller side performs abnormality diagnosis using the diagnostic signal and returns the diagnosis result to all human interface sides. All of the programmable controllers have abnormality diagnosis means for performing the abnormality diagnosis, and each of the plurality of human interfaces includes final diagnosis means, and each of these final diagnosis means has each programmable programmable controller. control Enter the diagnostic result from the abnormality diagnosis means performs a final diagnosis on the basis of this input, and wherein the.
The invention according to claim 2 is the invention according to claim 1, wherein the final diagnosis means of each human interface performs a final diagnosis based on a logical sum or majority of the diagnosis results from the diagnosis means of all the programmable controllers. It is what is performed.
[0010]
The invention according to claim 3 is the invention according to claim 1 or 2, characterized in that the communication performed between the programmable controller and the human interface is packet communication based on broadcast or multicast. .
[0011]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a block diagram showing a schematic configuration of a plant control system according to an embodiment of the present invention. On the transmission line L, HMI1 to HMI5 are connected, and PLC1 to PLC5 are connected. HMI1 to HMI5 have diagnostic signal transmitters A1 to A5 and final diagnostic means B1 to B5, respectively, and PLC1 to PLC5 have diagnostic means C1 to C5, respectively. In the conventional system shown in FIG. 3, only PLC1, which is “representative PLC”, has diagnostic means C1, but in the present invention, the concept of “representative PLC” disappears, and all of PLC1 to PLC5 have equivalent functions. The diagnostic means C1 to C5 are provided.
[0012]
In the system according to the present invention, the diagnostic signal s1 output from the diagnostic signal transmitter A1 of the HMI1 is transmitted to all of the PLC1 to PLC5 as indicated by the wavy line or the one-dot chain line arrow in FIG. Diagnosis is performed by PLC1 to PLC5. Each of these diagnosis result signals d1 to d5 is transmitted to final diagnosis means B1 to B5 of all HMI1 to HMI5. Each final diagnosis means B1 to B5 performs a final diagnosis based on all inputs of the diagnosis result signals d1 to d5. In the diagnosis result signals d1 to d5, the signal indicating the abnormality diagnosis result is a “1” signal, and the signal indicating the normal diagnosis result is a “0” signal.
[0013]
FIG. 2 is an explanatory diagram showing a configuration example of the final diagnosis means B1 in FIG. 1, where (a) is configured using the OR circuit OR1, and (b) is configured using the majority circuit M1. Show. The final diagnosis means B2 to B5 have the same configuration.
[0014]
In the final diagnosis means B1 in (a), the OR circuit OR1 outputs the final diagnosis result signal D based on the input of the diagnosis result signals d1 to d5 from the diagnosis means C1 to C5. That is, the logical sum circuit OR1 indicates that the final diagnosis result is abnormal when any one of these input signals includes a “1” signal indicating that it is abnormal. 1 "signal is output as the final diagnosis result signal D. If all the input signals are" 0 "signals indicating normality, the" 0 "signal indicating that the final diagnosis results are normal is final A diagnosis result signal D is output.
[0015]
On the other hand, in the final diagnosis means B1 in (b), the majority circuit M1 outputs the final diagnosis result signal D based on the input of the diagnosis result signals d1 to d5 from the diagnosis means C1 to C5. That is, the majority decision circuit M1 has an abnormal final diagnosis result when the number of “1” signals indicating abnormality among these input signals is greater than the value “0” indicating normality. “1” signal indicating that the final diagnosis result signal D is output, and if not, the “0” signal indicating that the final diagnosis result is normal is output as the final diagnosis result signal D. Yes.
[0016]
Next, the operation of FIG. 1 will be described. When the operator in charge of HMI1 performs a predetermined operation to activate HMI1, the diagnostic signal transmitter A1 of HMI1 transmits a diagnostic signal s1 for performing its own diagnosis to all of PLC1 to PLC5.
[0017]
In PLC1 to PLC5, the diagnostic means C1 to C5 input this diagnostic signal s1, independently perform abnormality diagnosis for HMI1, and output diagnostic result signals d1 to d5. Each of the diagnosis result signals d1 to d5 is transmitted to all of the HMI1 to HMI5 via the transmission line L. When the final diagnosis means B1 to B5 are constituted by an OR circuit as shown in FIG. 2A, each final diagnosis means outputs a logical sum of the diagnosis result signals d1 to d5 as described above. Based on the final diagnosis. Further, when the final diagnosis means B1 to B5 are constituted by a majority circuit as shown in FIG. 2B, each final diagnosis means is based on the majority of the diagnosis result signals d1 to d5 as described above. To make a final diagnosis.
[0018]
The above is the operation when diagnosing HMI1, but the same operation is performed for HMI2 to HMI5. For example, when diagnosing HMI2, diagnostic means C1-C5 inputs diagnostic signal s2 from diagnostic signal transmitter A2 of HMI2, and these diagnostic result signals d1-d5 are used as final diagnostic means B1-B5. Enter. Then, the final diagnosis means B1 to B5 perform a final diagnosis for the HMI2 based on the input of the diagnosis result signals d1 to d5.
[0019]
It should be noted that whether the final diagnosis means B1 to B5 is configured as shown in FIG. 2 (a) or 2 (b) is generally a safety-side misdiagnosis (diagnosis that is actually normal but abnormal). ) Is allowed, but the risky misdiagnosis (diagnosis that it is actually abnormal but normal) is not allowed, and the configuration of FIG. 2 (a) is adopted. If importance is placed on efficiency, the configuration of FIG. 2B will be adopted.
[0020]
Comparing the operation of FIG. 1 with the operation of FIG. 3, in FIG. 3, diagnosis is performed on an HMI (for example, HMI1) to be diagnosed by one PLC1 which is a “representative PLC”. In FIG. 1, all of PLC1 to PLC5 perform diagnosis for HMI1. Therefore, in FIG. 3, if a failure occurs in the PLC 1, the diagnosis cannot be performed, and even if it is possible, the diagnosis result is low in reliability. Further, when the operation of PLC1 is artificially stopped, not only the HMI1 but also other HMIs cannot be diagnosed during the suspension period.
[0021]
On the other hand, in the configuration of FIG. 1, since all of the diagnostic means C1 to C5 of PLC1 to PLC5 independently diagnose HMI1, if at least one of PLC1 to PLC5 is operating, Diagnosis can be performed even if no other PLC is operating. And it is extremely rare that all of PLC1 to PLC5 stop operating. Therefore, according to the system according to FIG. 1, it is possible to ensure a state in which an abnormality diagnosis for HMI can be performed substantially at all times.
[0022]
Here, the communication method between HMI1 to HMI5 and PLC1 to PLC5 will be described. In this embodiment, a UDP (User Datagram Protocol) / TCP (Transmission Control Protocol), that is, a packet communication method based on broadcast or multicast is adopted. Assumes that. This is because the data transmitted and received between the HMI1 to HMI5 and the PLC1 to PLC5 are the same, and the communication software can be further simplified by adopting such a communication method.
[0023]
【The invention's effect】
As described above, according to the present invention, all of the plurality of programmable controllers have abnormality diagnosis means, and each of the plurality of human interfaces inputs diagnosis results from all abnormality diagnosis means. Since the final diagnosis is performed based on the input, it is always possible to perform an abnormality diagnosis for the HMI, and the reliability of the entire system can be improved.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a schematic configuration of a plant control system according to an embodiment of the present invention.
FIGS. 2A and 2B are explanatory diagrams showing a configuration example of the final diagnosis unit B1 in FIG. 1, in which FIG. 2A shows a case where a logical sum circuit OR1 is used, and FIG. 2B shows a case where a majority circuit M1 is used. Show.
FIG. 3 is a block diagram showing a schematic configuration of a conventional plant control system.
[Explanation of symbols]
HMI1 to HMI5 Human interface A1 to A5 Diagnostic signal transmitters B1 to B5 Final diagnostic means PLC1 to PLC5 Programmable controller C1 to C5 Diagnostic means s1 Diagnostic signals d1 to d5 Diagnostic result signal OR1 OR circuit M1 Majority circuit D Final Diagnostic result signal L Transmission line

Claims (3)

Multiple programmable controllers and multiple human interfaces are connected on the transmission line, and diagnostic signals are sent from the human interface to be diagnosed to the programmable controller. In the plant control system that performs abnormality diagnosis using signals and returns the diagnosis result to all human interfaces,
The plurality of programmable controllers all have abnormality diagnosis means for performing the abnormality diagnosis,
Each of the plurality of human interfaces includes a final diagnosis unit, and each of these final diagnosis units inputs a diagnosis result from the abnormality diagnosis unit of all the programmable controllers and performs a final diagnosis based on the input. Is,
A plant control system characterized by that. The final diagnosis means of each human interface performs final diagnosis based on the logical sum or majority of the diagnosis results from the diagnosis means of all the programmable controllers.
The plant control system according to claim 1. Communication performed between the programmable controller and the human interface is packet communication based on broadcast or multicast.
The plant control system according to claim 1 or 2, characterized by the above-mentioned.

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