JPH0883117A - Warning value detecting method for process - Google Patents

Abstract

PURPOSE: To correctly display warning values in the order of warning value generation with respect to a warning value detecting method for process monitoring a system to be controlled by plural process controllers connected to a main controller by using a process monitoring device. CONSTITUTION: With respect to process controllers PCA1 and PCA2 for controlling a system controlled to be, guarantee time expressing transmission time is transmitted to a process monitoring device 2A as alarm information at prescribed intervals as long as there is a space in a signal line SB while adding a detected alarm value and alarm value detection time of it when the alarm value is detected, and the transmitted alarm information is stored in a storage means 23 of the process monitoring device 2A. Since a central processing unit 21 cyclically executes an alarm collection program 22AP and a display program DP at prescribed time intervals, when the alarm value is contained in the alarm information, processing is successively started from the data of the alarm value detection time, for which the detection time is the alarm value is preceding to the oldest guarantee time in the alarm information, and the those data are displayed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for detecting an abnormal value, which may occur during a control process, as an alarm value by a process monitoring device in a system for controlling a controlled object by a plurality of process control devices. .

[0002]

2. Description of the Related Art FIG. 6 shows an example of a controlled object. In the figure, the control target CO1 and the control target CO2 are shown among all the control targets. The controlled CO1 is the liquid supplied to the tank TK1.
It is a device that heats RQ1 to a predetermined temperature with a heater HT1 and then sends it out with a pump PM1. The outflow rate of the liquid RQ1 is controlled by the valve so that the flow rate detected by the flow meter FL1 falls within the specified range.
It is controlled by the opening of V13. The inflow of liquid RQ1 is
The liquid level of the liquid RQ1 is detected by the liquid level gauge QL1 and is controlled by the opening degree of the valve V11 so that the liquid level falls within a predetermined range. Further, the temperature of the liquid RQ1 is detected by the temperature sensor TH1, and the detected temperature is compared with the reference temperature, and the heater
The flow rate of steam, which is the heat source of HT1, is controlled to a predetermined temperature by controlling the opening of the valve V12. Control target
CO2 is a device having the same function as that of the control target CO1, and is a device that sends the liquid RQ2 supplied to the tank TK2 to a predetermined temperature by the heater HT2 and then sends it by the pump PM2. In the figure, V21 is a valve that controls the inflow of liquid RQ2, V22 is a valve that controls the flow rate of steam that serves as a heat source, V23 is a valve that controls the outflow of liquid RQ2, TH2 is a temperature sensor, and QL2 is a level gauge. , FL2 are flow meters, and the operation of these is the same as that of the same name and similar purpose shown in FIG.

FIG. 7 shows an example of a control system including a process control device and a process monitoring device for controlling the device shown in FIG. In the figure, 1 is a main controller, PC1 is a first process controller, PC2 is a second process controller, and the first process controller PC1 is a temperature sensor TH1 for the controlled object CO1 shown in FIG. The signal from the flow meter FL1 etc. is input to control the controlled CO1 and the second process controller
The PC2 inputs signals from the temperature sensor TH2 of the control target CO2 and the flow meter FL2 shown in FIG. 6 to control the control target CO2. The main control device 1 includes a first process control device PC1 via a signal line SB forming a LAN (Local Area Network),
And send and receive signals to and from the process controller PC2,
These process control devices are controlled by referring to the information from the first and second process control devices. A process monitor 2 is connected to the first process controller PC1 and the second process controller PC2 via a signal line SB.

An alarm value indicating an abnormal state during the stroke of the system shown in FIG. 7 is detected as described below. In the process control device COi (i is number 1 or 2), a limit value corresponding to a boundary value between a normal value and an abnormal value is set in advance for each controlled variable to be controlled. For example, a lower limit temperature Td1 (not shown) and an upper limit temperature Tp1 (not shown) are given as limit values of the temperature of the control target PC1. Process control device PC1
Input the temperature detected by the temperature sensor TH1 at a predetermined time interval, compare the input temperature with the lower limit temperature Td1 and the upper limit temperature Tp1, and if the input temperature is lower than the lower limit temperature Td1 or higher than the upper limit temperature Tp1. The input temperature is stored as an alarm value in the storage means MP1 provided in the process control device PC1. Similarly, in the process control device PC2, when the alarm value is detected, the detected alarm value is stored in the storage means MP2 provided inside the process control device PC2. As long as the signal line SB is free, the process monitoring device searches for the alarm value stored in the storage means MPi (i is the number 1 or 2) of the process control device PCi at regular time intervals, and issues an alarm. If there is a value, this alarm value is read and displayed on the display unit of the process monitoring device 2.

[0005]

As described above, the process monitoring device uses the alarm value detected by the process control device and stored in the storage means of the process control device during the time period when the signal line is vacant. It is read out and displayed on the display unit of the self-monitoring device. However, since the signal line is used by various signals, it is not always always available at the time when the alarm value is read from the process monitoring device, and may be read at a time delayed from the time. If there are cases where the alarm values are read out at a time later than the scheduled time, if there are multiple alarm values, the order in which the alarm values occur may not match the time when the alarm values were read by the process monitoring device. In this case, the display order of the alarm values displayed on the process control device and the generation order of the alarm values do not match. On the other hand, the purpose of displaying the alarm value on the process monitoring device is
At the same time as notifying the detection of the alarm value and prompting the process to return to a normal state, it is to give a clue as to the cause of the alarm value generation. Need to show. Therefore,
In some cases, the display order and the alarm value generation order may not coincide with each other, because it is erroneous in determining the cause of the alarm value generation, which is extremely undesirable.

In view of the above-mentioned circumstances, an object of the present invention is to, when an alarm value is detected, display the detected alarm value correctly on the display unit of the process monitoring device in the order of the alarm value detection time. It is to provide a value detection method.

[0007]

To achieve the above object, according to the first invention, a system for controlling a controlled object by a plurality of process control devices connected to a main control device by a signal line is provided. In the method for detecting an alarm value of a process, which detects an abnormal value that may occur during a control process as an alarm value by a process monitoring device, each process control device is provided with a storage unit, and the storage unit stores the control amount of the control amount. A limit value of the boundary value between the normal value and the alarm value is stored, and a function of detecting the alarm value based on this limit value and a function of storing the detection time when the alarm value is detected are provided, and For each process control device, select the case where the signal line is vacant, and send this time to the process monitoring device as the guaranteed time at every predetermined time of the predetermined time interval, and the alarm value is detected when the guaranteed time is transmitted. If it is characterized in that to transmit the detection time of the alarm value and the alarm value followed guaranteed time to process monitoring device.

According to the second aspect of the invention, the alarm value time-series storage area for storing the alarm values in the storage means in the process monitoring device in the order of detection time, the guaranteed time, the alarm value and the alarm from each process control device. An alarm information area for each process control device, which is composed of the value detection time and other data related to the alarm value, is provided, and the guaranteed time, the alarm value, and the alarm value detection time transmitted from each process control device are applicable. Stored in the alarm information area for each process control device, and detect the oldest oldest guaranteed time in the guaranteed time and the oldest oldest alarm value in the alarm value detection time from the alarm information area in a predetermined cycle. If the alarm value detection time does not exist or the oldest alarm value detection time is newer than the oldest guaranteed time, the process of excluding the oldest guaranteed time is performed, and the alarms older than the oldest guaranteed time are searched. Value detection time exists In this case, the oldest alarm value detection time and the alarm value detected at this time are stored in the alarm value time series storage area, and the oldest alarm value detection time and the oldest alarm value detection time in the alarm information area are stored. , The alarm value stored in the alarm value time series storage area and the alarm value detection time at the time when this alarm value is detected are time-series. It is characterized in that they are sequentially displayed on the display unit of the process monitoring device.

Further, according to the third aspect of the invention, prior to the start of control of the controlled object, a limit value serving as a reference for alarm value detection and other data related to alarm value detection are controlled from the process monitoring device. It is characterized in that it is stored in the storage means of the process control device constituting the system.

[0010]

In the process alarm value detection method of the first invention, each process control device for controlling the controlled object compares the control amount measured during the control process with the limit value, and the measured control amount is When the limit value is exceeded, this measured value is stored as an alarm value, and the time when this alarm value is detected is stored as an alarm value detection time in the internal storage means of the process control device. On the other hand, when the signal line is vacant, it is selected and transmitted to the process monitoring device at a predetermined time of a predetermined time interval with the transmission time as the guaranteed time. If the alarm value is stored in the storage means when the security time is transmitted, the alarm value and the detection time of this alarm value are transmitted to the process monitoring device subsequent to the transmission of the security time.

Further, in the alarm value detecting method for a process according to the second aspect of the present invention, the process monitoring device transmits the guarantee time transmitted from the process control device, and the alarm value and the alarm value detection time other than the guarantee time. In this case, the guarantee time, the alarm value, and the alarm value detection time are stored in the alarm information area provided in the storage means of the process monitoring device for each process control device. Further, the process monitoring device searches the alarm information area for the oldest guaranteed time. If there is an alarm value that occurred before the earliest guaranteed time, the oldest alarm value detection time is searched from the alarm information area, and the alarm value detected at the oldest alarm time and the oldest alarm value. The detection time is stored in the alarm value time series storage area, and after the storage, the stored alarm value and the oldest alarm value detection time are read out to display the alarm value, the alarm value detection time, and the guaranteed time. To disable. Further, the process monitoring device displays the alarm value stored in the alarm value time series storage area and the alarm value detection time when the alarm value is detected in time series on the display unit of the process monitoring device.

Further, in the alarm value detecting method for a process according to the third aspect of the present invention, when starting the control of the controlled object,
Prior to the start of control, a limit value serving as a reference for alarm value detection and other data related to the detection of the alarm value are stored from the process monitoring device in the storage means of the process control device constituting the control system, Each process controller uses this stored limit value as a reference and refers to other data associated with the detection of the alarm value to detect the alarm value.

[0013]

【Example】

(Embodiment 1) FIG. 1 shows an example of a system to which the present method is applied as an embodiment of a method for detecting a warning value of a process according to the methods of the first and second inventions. In the following description, the same code is used for the code representing the data and the area of the storage unit that stores this data. 1A is a diagram showing the main part of the system, in which 2A is a process monitoring device, PCA1 is a first process control device, PCA2 is a second process control device, and SB is a process. It is a signal line for transmitting a signal between the monitoring device 2A and the process control device PCAi (i is number 1 or 2).

The process monitor 2A includes a program storage means 22 for storing a program including an alarm value collection program 22AP and a display program 22DP, and a central processing unit 21 for executing the program stored in the program storage means.
, Data storage means 23, input means 25, and central processing unit
The display means 26 performs a display operation by a display program executed by 21, and is connected to the process control device PCA1 and the process control device PCA2 via the signal line SB via the interface 24. The process controller PCA1 is shown in Fig. 6.
In order to control the control target CO1 shown in
The temperature sensor TH1 and the flow meter FL1 of are connected.
The process control computer PCA2 is the control target CO2 shown in FIG.
In order to control the CO2, a temperature sensor TH2 for the CO2 to be controlled, a flow meter FL2, etc. are connected. FIG. 1 (b) is a block diagram showing the inside of the process control device PCAi. In the figure, 21Pi is a control calculation means and 22Pi is a process control device PC.
Temperature sensor TH connected to i via input / output circuit 27Pi
i, a data collection program DCP that inputs and processes data from the flow meter FLi, etc., and the process monitoring device via the signal line SB via the interface 24Pi and the processed data
2P is a program storage means for storing a program including a data transmission program DSP and 23Pi is data including a limit value LDi, a detected alarm value ADi, and an alarm value detection time ATi representing the detection time of the alarm value. Is a data storage means for storing.

FIG. 2 (a) shows a storage area of the data storage means 23 of the process monitoring apparatus 2A shown in FIG. 1 (a). In the figure, AL1 is an area for storing alarm information AL1 transmitted from the process control device PC1, AL2 is an area for storing alarm information AL2 transmitted from the process control device PC2, and n alarms up to ALn Area of information is secured. ADT is a storage area for alarm time series. FI is a flag, which is a storage area secured in the storage means 23 together with other data not shown. 2 (b), the alarm information storage area ALi shown in FIG. 2 (a) (i is a numerical value 1 or 2 indicating a number)
Indicates the contents of. In the figure, ADi is alarm data, and the alarm data ADi is composed of the part APi to be monitored in the controlled object, the limit value AVi, the detected value SVi of the measured value of the controlled variable of the controlled object, and the like. ATi is the detection value SVi that exceeds the limit value AVi, that is,
The alarm value detection time indicates the time when the alarm value is detected, and ATSi is the guaranteed time indicating the transmission time to the process monitoring device 2A.

The display process of the alarm value in the control system shown in FIG. 1A is performed as described below. If the process control device PCAi (i is a numerical value 1 or 2 representing a number) does not detect an alarm value at the time of transmission of the regular guaranteed time, the process time is set as the guaranteed time and only the guaranteed time is set as the process monitoring device 2A. And the transmitted guaranteed time is stored in the alarm information area ALi (i is a number corresponding to the number i of the process controller PCAi) assigned to the process controller PCi. Further, when the alarm value is detected at the transmission time of the regular guaranteed time, the process control device PCAi transmits the transmission time as the guaranteed time, and following the transmission of the guaranteed time, the detected alarm value and this The alarm value detection time indicating the time at which the alarm value is detected is transmitted, and these transmitted data are stored in the alarm information area ALi.

On the other hand, the central processing unit 21 of the process monitoring device 2A
Executes the alarm value collection program 22AP at regular intervals to search the alarm information area ALi and display the earliest time among the guaranteed times. And the alarm value detection time, which is the earliest of the alarm value detection times (hereinafter referred to as the oldest alarm value detection time). If the alarm value detection time does not exist or the oldest alarm value detection time that is earlier than the oldest guaranteed time does not exist, it means that the alarm value did not exist before this oldest guaranteed time. Since there is no need to refer to this oldest guaranteed time, this oldest guaranteed time is excluded when searching for the next oldest guaranteed time. If the oldest alarm value detection time before the oldest guaranteed time exists, this oldest alarm value detection time and the alarm value detected at this time are already stored in the alarm value time series storage area. If any data is stored, it is stored in the order following the previous data. With this storage, the processing for the stored data ends, so the stored alarm value, the alarm value detection time of this alarm value, and the guaranteed value time of transmitting this alarm value are excluded, and the processing of the next cycle is performed. enter. By repeating the processing of the above-described cycle, the alarm value and the alarm value detection time are stored in the alarm value time series storage area in the order of the time of occurrence. For the sake of convenience, a series of processes from the search of the oldest guaranteed time to the search of the next oldest guaranteed time will be referred to as one search cycle in the following description. The central processing unit 21 displays the alarm value and the alarm value detection time stored in the alarm value time-series storage area in the order of storage by executing the display program 22DP every fixed number of search cycles. The displayed contents are
As described above, since the alarm values are stored in the time-series order in which they are detected, the alarm value and the alarm value detection time point are displayed in the order of the occurrence time system.

FIG. 3 shows, as an example, the display order of alarm values when both alarm information AL1 and alarm information AL2 include alarm values. In the figure, the passage of time goes from top to bottom. Shown as one. In the first search cycle, since the guaranteed time ATS1 of the alarm information AL1 is earlier than the guaranteed time ATS2 of the alarm information AL2, the guaranteed time ATS1 is the maximum when there are only two process control devices PCAi. The old security time comes. When the alarm value detection time is searched, there are the alarm value detection time AT1 and the alarm value detection time AT2, and since there are only two alarm value detection times, the alarm value detection time AT
2 is the oldest alarm value detection time. Comparing the oldest security time ATS1 and the oldest alarm value detection time AT2, the oldest alarm value detection time AT2 is a time before the oldest security time ATS1, so
The alarm value detection time AT2 and the alarm value SV2 at this time are stored in the alarm value time series storage area ADT (see (a) in FIG. 2). In the next search cycle, the displayed alarm value SV2, alarm value detection time AT2 and guaranteed time ATS2 are excluded, and the oldest guaranteed time
ATS1 remains as the earliest guaranteed time, the oldest alarm value detection time becomes alarm value detection time AT1, and alarm value SV1 and alarm value detection time AT1 are the previously stored alarm value SV2 and alarm value detection It is stored in the alarm value time series storage area following time AT2. The stored results are stored in the central processing unit 21 (see FIG. 1).
(See (a)) is displayed on the display means 26 (see (a) in FIG. 1) in the storage order by executing the display program 22DP.

FIG. 4 shows a search for storing the alarm value and the alarm value detection time in the alarm value time series storage area ADT shown in FIG. 2A in the alarm value display process described above. It is a flow chart which shows a cycle. As shown in FIG.
Process control equipment in the system shown in (a) of
By executing the alarm value collection program 22AP, the central processing unit 21 of 2A first searches in process F10 the oldest guaranteed time from the alarm information ALi stored in the data storage means 23, and then executes process F11. In the alarm information AL
The oldest alarm value detection time is retrieved from i. Next process F1
In 2, the oldest alarm value detection time is compared with the oldest guaranteed time, and if the oldest alarm value detected time is earlier than the oldest guaranteed time, the process proceeds to process F13, and the oldest searched for in this process is executed. The alarm value detection time and the alarm value detected at this time are stored in the alarm value time series storage area, and the process proceeds to step F14.
In process F14, the alarm value detection time stored in process F13 and the alarm value are excluded from the next search cycle, and the process proceeds to process F15. In process F15, process
The guaranteed time of the alarm value etc. stored in F15 is excluded from the next detection cycle and the process moves to the next search cycle. On the other hand, in process F12, when the oldest alarm value detection time is newer than the oldest guaranteed time or when the alarm value detection time does not exist, the process proceeds to process F16.
In process F16, the oldest guaranteed time being searched is excluded from the next search cycle, and the process shifts to the next search cycle. (Embodiment 2) FIG. 5 is a limit value and an alarm which are reference values for alarm value detection performed prior to the start of control of a controlled object in an example of a system to which the method for detecting an alarm value of the third invention is applied. It is a flowchart which shows the process which stores other data relevant to value detection from a process monitoring apparatus in a process control apparatus. The process shown in this flowchart is performed by setting an unset flag FI (see (a) in FIG. 2) provided in the storage means 23 of the process monitoring device 2A in the same system as that shown in (a) in FIG. Since it is performed by using the area, the system of this embodiment has
The system is the same as the system shown in FIG. 1 (a), and the description of the system is omitted.

Process monitoring device 2A (see FIG. 1 (a))
When is started, the process monitoring device first detects whether or not the control of the controlled object is continuously executed by the main controller (not shown) and the controlled object is operating normally. For example, if the operation is stopped due to an inspection or the like, it is not a normal operation state, and therefore the process proceeds to step F5 and the unset flag provided in the area of the data storage means 23 (see (a) of FIG. 2).
The content of FI is set to 1 (that is, the flag FI is set), and the process F1 and the process F5 are repeated until the control action becomes the operating state, and the process waits. When the normal operation is started, the process proceeds to the process F2, and in the process F2, it is determined whether or not the content of the unset flag FI is 1. If the content of the unset flag FI is 1, the process monitoring device 2A is in the initial state. This means that the process control device proceeds to the process F3, and in this process, the alarm information including the limit value for detecting the alarm value in each part of the control target and other data related to the alarm value detection is displayed. PC
It is stored in the storage means 23Pi of Ai (see (a) of FIG. 1). For example, the number for identifying the temperature sensor THi that is the target of the alarm value detection, the temperature as the limit value, and the like are stored. Next, in process F4, the content of the unset flag FI is set to 0. That is, the unset flag is cleared. If the process from the process F1 is executed again at a later point in time, the unset flag FI has already been cleared and therefore the alarm information is not stored again. If the controlled operation is stopped and restarted,
Since the process F5 is executed based on the determination of the process F1, the alarm information is newly stored in the process control device PCAi.

[0021]

As described above, the method of the first aspect of the present invention comprises a system for controlling a controlled object by a plurality of process control devices connected to the main control device by signal lines,
An alarm value detection method for a process, wherein an abnormal value that may occur during a control process is detected by a process monitoring device as an alarm value, in each process control device, a storage means is provided, and a limit value is stored in this storage means. Then, a function to detect the alarm value based on this limit value and a function to store the detection time when the alarm value is detected are added, and the case where the signal line is vacant for each process control device is selected. Then, at every predetermined time of a predetermined time interval, this time is transmitted as a guaranteed time to the process monitoring device, and if an alarm value is detected when the guaranteed time is transmitted, the alarm value and the alarm value are detected following the guaranteed time. The time and are transmitted to the process monitoring device.

Therefore, according to the method of the first aspect of the present invention, the alarm value is immediately detected by the process control device for controlling the controlled object, so that the detection time of the alarm value is approximately the alarm generation time. Even if the alarm detection time is equal to the detection time of the value and there is a difference between the time when the alarm value was detected to wait for the signal line to be empty and the time when the alarm value was sent, the alarm value is detected by referring to the alarm value detection time. Since the order of time becomes clear, it is possible to correctly know the time of occurrence of the alarm value in the order of time of occurrence.

In the method of the second aspect of the invention, the alarm value time-series storage area for storing the alarm values in the order of detection time in the storage means in the process monitoring device, the guaranteed time, the alarm value and the alarm from each process control device. An alarm information area for each process control device, which is composed of the value detection time and other data related to the alarm value, is provided, and the guaranteed time, the alarm value, and the alarm value detection time transmitted from each process control device are applicable. Stored in the alarm information area for each process control device, and detect the oldest oldest guaranteed time in the guaranteed time and the oldest oldest alarm value in the alarm value detection time from the alarm information area in a predetermined cycle. If the alarm value detection time does not exist or the oldest alarm value detection time is newer than the oldest guaranteed time, the process of excluding the oldest guaranteed time is performed, and the alarms older than the oldest guaranteed time are searched. Value detection time exists When the oldest warning value detection time and the warning value detected at this time are stored in the warning value time series storage area, the oldest warning value detection time and the oldest warning value detection time in the warning information area are stored. , The alarm value stored in the alarm value time series storage area and the alarm value detection time at the time when this alarm value is detected It is displayed on the display unit of the process monitoring device in sequence order. Therefore, according to the method of the second invention, the alarm value can be correctly displayed according to the order of occurrence.

Further, in the method of the third aspect of the invention, prior to the start of control of the controlled object, a limit value serving as a reference for alarm value detection and other data related to alarm value detection are controlled from the process monitoring device. It is stored in the storage means of the process control device constituting the system. Therefore, according to the method of the third invention, even if the limit value of the controlled variable of the controlled object is changed, for example, in a plant that manufactures beverages having different mixing ratios, the components to be mixed due to the difference in the types of the beverages. When it is necessary to change the limit value of the liquid flow rate, the limit value of the process control device that controls the controlled object can be automatically set from the process monitoring device without setting the limit value for each process control device at the installation location. The limit value is stored in the process control device, and the alarm value is correctly detected for each product.

[Brief description of drawings]

1A and 1B are diagrams showing an embodiment of a method for detecting a warning value of a process according to the method of the present invention, in which FIG. 1A is a diagram showing a system for controlling a process to be controlled, and FIG. Internal block diagram

FIG. 2 is a diagram showing the contents of data storage means of the process monitoring device shown in FIG. 1A, in which FIG. 2A shows alarm information, an alarm value time series storage area, and other data areas. Figure,
(b) is a diagram showing the content of alarm value information

FIG. 3 is a diagram illustrating a display order of alarm values.

FIG. 4 is a flowchart showing an operation at the time of starting the process monitoring device shown in FIG.

FIG. 5 is a flowchart showing the operation of the process monitoring apparatus of another embodiment of the process alarm value detection method according to the present invention.

FIG. 6 is a diagram showing an example of a control target of process control to which a process alarm value detection method is applied.

FIG. 7 is a diagram showing an example of a process control system to which a conventional process alarm value detection method is applied.

[Explanation of symbols]

 2A Process monitoring device 21 Central processing unit 22 Program storage means 22AP Alarm value collection program 22DP display program 23 Data storage means 25 Input means 26 Display means PCA1 First process control device PCA2 Second process control device

Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location G08B 29/26 8621-2E

Claims (3)

[Claims] 1. A process monitor in which an abnormal value that may occur during a control process of a system in which a control target is controlled by a plurality of process control units connected to a main control unit by a signal line is used as an alarm value. In the method of detecting an alarm value of a process detected by a device, each process control device is provided with a storage means, and the storage means stores a limit value of a boundary value between a normal value of a control amount and an alarm value. With the function to detect the alarm value based on
Add a function to memorize the detection time when the alarm value was detected,
In addition, each process control device selects the case where the signal line is vacant and causes the process monitoring device to transmit this time as a guaranteed time at every predetermined time of a predetermined time interval, and an alarm value is detected when the guaranteed time is transmitted. If so, a method for detecting an alarm value of a process is characterized in that the alarm value and the detection time of the alarm value are transmitted to the process monitoring device after the guaranteed time. 2. The alarm value detection method for a process according to claim 1, wherein an alarm value time series storage area for storing alarm values in detection time order in a storage means in the process monitoring device, and guarantees from each process control device. An alarm information area for each process control device, which includes time, alarm value, detection time of alarm value, and other data related to the alarm value, is provided, and the guaranteed time, alarm value, and alarm value transmitted from each process control device are provided. The detection time is stored in the alarm information area of each applicable process control device, and the oldest guaranteed time of the earliest guaranteed time from the alarm information area and the earliest of the alarm value detection times from the alarm information area in a predetermined cycle. The oldest alarm value detection time of is searched, and if the alarm value detection time does not exist or the oldest alarm value detection time is newer than the oldest security time, the oldest security time is excluded and the oldest Past warranty time If the alarm value detection time of is present, the oldest alarm value detection time and the alarm value detected at this time are stored in the alarm value time series storage area, and the oldest alarm value detection time in the alarm information area is stored. And the alarm value at the oldest alarm value detection time are excluded, and the alarm value stored in the alarm value time-series storage area and the alarm value at the time when this alarm value is detected each time a certain number of times of a predetermined cycle elapses. A method for detecting an alarm value of a process, characterized by displaying the alarm value detection time on a display unit of a process monitoring device in chronological order. 3. The process alarm value detection method according to claim 1, wherein a limit value serving as a reference for alarm value detection and other data related to the alarm value detection are provided prior to the start of control of the controlled object. A method for detecting a warning value of a process, characterized by storing the process monitoring device in a storage means of a process control device constituting a control system.