JP7679290B2 - Machine monitoring system, monitoring device, and monitoring method - Google Patents

Description

The present invention relates to a machine monitoring system, a monitoring device, and a monitoring method.

A machine monitoring system may be installed to manage the actual production volume for each specified period, for example each day, of monitored equipment such as production equipment installed in a factory. In such a machine monitoring system, a node device connected to the monitored equipment counts the production value each time it receives a signal indicating production (pulse signal, digital signal, etc.) output from the monitored equipment. A higher-level monitoring device then obtains the production value from the node device and manages the actual production volume for each specified period.

The node device stores the counted production figures in volatile memory, and rounds up when it reaches a specified maximum count value (for example, 262,143 when stored in 18 bits). In order to manage the actual production numbers that change each day, it is possible to reset the production figures of the node device for each working day, but count resets are not performed because sending a count reset signal from the monitoring device to the node device would cause data delays that would make it impossible to accurately tally up the counts, and complex control would be required to handle node devices that do not respond because they are powered off, etc. The node device obtains its power from the equipment being monitored.

In addition, to deal with the problem of the production unit values being erased from the volatile memory when the power is turned off, the node device takes into consideration the limit on the number of times nonvolatile memory such as flash memory can be written to, and stores the production unit values in the nonvolatile memory when power is turned off, and writes them back from the nonvolatile memory to the volatile memory when power is turned on. In other words, when a drop in the power supply voltage is detected, the production unit values in the volatile memory are stored in the nonvolatile memory within the time that the capacitor can store electricity, and when power is turned on, the production unit values are read from the nonvolatile memory and written to the volatile memory.

The upper monitoring device mainly performs the following three processes based on the production unit values obtained from the node device:
- The actual daily production numbers are managed by normal count-up processing, round-up processing, and count correction processing.

Normal count-up processing occurs when the latest production value obtained from the node device is not lower than the previous production value (if it has increased or is unchanged), and the difference from the previous production value is added to the actual production number.

In the round-up process, if the latest production value obtained from the node device is lower than the previous production value, and the difference between the previous production value and the latest production value exceeds a predetermined threshold that is more than half of the maximum count value (for example, when stored in 18 bits, it is 209,714, which is 80% of 262,143), it is determined that a round-up has occurred, and the actual production number is calculated by supplementing the number in the rounded-up interval while taking into account the maximum count value. A technology similar to the round-up process here (a pulse counter that can count the number of pulses up to a value exceeding the upper limit of the counting unit) is disclosed in Patent Document 1.

The count correction process is a process that does not increase the actual production number if the latest production value obtained from the node device is lower than the previous production value, or if the difference between the previous production value and the latest production value does not exceed the above threshold, and it is determined that there is an error in the latest production value obtained from the node device.

Patent No. 6756883

In the above machine monitoring system, most errors could be addressed by count correction processing, but there was a problem in that if a spontaneous reset of a node device occurred at a specific timing, it would result in an abnormal increase in the actual production volume. Spontaneous reset of a node device here refers to the rare phenomenon in which a reset occurs 30 to 120 seconds after the node device is powered on when the time between powering it off and powering it on is short.

The present invention has been made in consideration of the above, and aims to provide a machine monitoring system etc. that does not cause an abnormal increase in actual production volume even if a spontaneous reset of a node device occurs.

In order to solve the above-mentioned problems and achieve the object, a machine monitoring system according to one aspect of the present invention includes a node device and a monitoring device. The node device counts the production value every time it acquires a signal indicating production output from the equipment to be monitored, stores it in a volatile memory, rounds up when a predetermined maximum count is reached, stores the production value in a non-volatile memory when power off is detected, and writes it back to the volatile memory when power is turned on. The monitoring device acquires the production value from the node device and manages the actual production number for each predetermined period. When the latest production value acquired from the node device is lower than the previous production value, the monitoring device determines that a round-up has occurred and calculates the actual production number when the difference between the previous production value and the latest production value exceeds a predetermined threshold that is a majority of the maximum count, and performs a correction process that does not increase the actual production number when the difference between the previous production value and the latest production value does not exceed the threshold.

A machine monitoring system according to one aspect of the present invention can prevent an abnormal increase in actual production volume even if a spontaneous reset of a node device occurs.

FIG. 1 is a diagram illustrating an example of a configuration of a machine monitoring system according to an embodiment. FIG. 2 is a flowchart showing an example of processing that is performed each time data is acquired for each node device from the time the day changes in the monitoring device. FIG. 3 is a flow chart showing an example of a normal count-up process in FIG. FIG. 4 is a flowchart showing an example of the round-up process in FIG. FIG. 5 is a flowchart showing an example of the count correction process in FIG. FIG. 6 is a flowchart showing a processing example of a comparative example including a problem. FIG. 7 is a diagram showing an example of normal changes in the production value of node devices. FIG. 8 is a diagram showing an example of production unit values acquired from node devices in the monitoring device and determined actual production numbers. FIG. 9 is a diagram showing an example in which the production unit values acquired from the node devices by the monitoring device are not consecutive values. FIG. 10 is a diagram showing an example of correction when the production value acquired from the node device in the monitoring device is decreased due to a defect. FIG. 11 is a diagram showing an example of a defect in which an erroneous Roundup process causes a sudden increase in actual production. FIG. 12 is a diagram showing an example of a problem in which a sudden increase in the actual production volume occurs due to an erroneous normal count-up process. FIG. 13 is a diagram showing an example in which the problem in FIG. 12 is solved according to the embodiment. FIG. 14 is a diagram showing an example in which the problem in FIG. 11 is solved according to the embodiment. FIG. 15 is a diagram illustrating an example of a normal round-up process according to an embodiment.

Below, the machine monitoring system, monitoring device, and monitoring method according to the embodiment will be described with reference to the drawings. Note that the present invention is not limited to the embodiment. Furthermore, the dimensional relationships of the elements in the drawings, the ratios of the elements, etc. may differ from reality. The drawings may also include parts with different dimensional relationships and ratios. Furthermore, the contents described in one embodiment or modified example are, in principle, applicable to other embodiments or modified examples in the same way.

FIG. 1 is a diagram showing an example of the configuration of a machine monitoring system 1 according to one embodiment. In FIG. 1, factories F1, F2, etc. are provided with a plurality of monitored equipment 2 such as production equipment, and a plurality of node devices 3 each connected by wire to the monitored equipment 2. The node devices 3 obtain power from the monitored equipment 2. In addition, factories F1, F2, etc. are provided with a monitoring device 4 for every predetermined number of node devices 3, and the monitoring devices 4 and the node devices 3 are connected by short-range wireless such as Bluetooth (registered trademark) Mesh.

The monitoring devices 4 of each factory F1, F2, ... are connected to a firewall device 5 in the management office AF via a wide area network (WAN), local area network (LAN), etc. A time server device 6 and multiple terminal devices 7 are connected to the firewall device 5. The time server device 6 is used by the monitoring devices 4 to refer to date and time information for daily processing, etc. The terminal devices 7 are used by the web server function provided by the monitoring devices 4 to refer to the actual production volume for each piece of equipment 2 to be monitored.

The node device 3 and the monitoring device 4 are computer devices that include an arithmetic unit, a storage device, an input/output device, etc., and execute predetermined processing based on a computer program stored in the storage device. In addition, the node device 3 and the monitoring device 4 perform basic operations as described in the background art.

Figure 2 is a flowchart showing an example of processing performed by the monitoring device 4 each time data is acquired for each node device 3 from the time the day changes. Figure 3 is a flowchart showing an example of normal count-up processing (step S5) in Figure 2. Figure 4 is a flowchart showing an example of round-up processing (step S7) in Figure 2. Figure 5 is a flowchart showing an example of count correction processing (step S8) in Figure 2.

Before describing the processing in the embodiment, the processing in the comparative example will be described first in order to explain the previous problem (the problem of an abnormal increase in the actual production volume when a spontaneous reset of a node device occurs). Figure 6 is a flowchart showing an example of the processing in the comparative example including the problem.

In FIG. 6, the monitoring device 4 sets the production value at the time of the change of the day to the variable PreVal (step S1'). FIG. 7 is a diagram showing an example of normal changes in the production value of the node device 3, where the production value increases by one each time production is detected and returns to "1" when it reaches the maximum count value of "262,143". FIG. 8 is a diagram showing an example of the production value acquired from the node device 3 by the monitoring device 4 and the determined actual production number. Here, "210,000" is set to the variable PreVal as the production value at the time of the change of the day. Also, the actual production number at this point is "0".

Next, in FIG. 6, when the monitoring device 4 acquires the production value from the node device 3, it sets the latest production value to the variable CurVal (step S2') and determines whether the variable CurVal is smaller than the variable PreVal (CurVal<PreVal) (step S3'). Note that the monitoring device 4 acquires the production value from the node device 3 by making data acquisition requests to the multiple registered node devices 3 in a predetermined order.

If the monitoring device 4 determines that the variable CurVal is not smaller than the variable PreVal (No in step S3'), it executes normal count-up processing (step S5'). The normal count-up processing is similar to that shown in FIG. 3, in which the actual production number at that time is set to the variable ProductCnt (step S51), CurVal-PreVal is set as the increment in the production number (step S52), and ProductCnt + the increment in the production number is set as the actual production number (step S53).

For example, in the second box from the left in Figure 8 (first acquisition after the day change), the variable CurVal is "210,001", which is not smaller (has increased) than the variable PreVal "210,000", so normal count-up processing is performed, and the variable ProductCnt becomes "0", which is the previous actual production number, and the increase in the production number becomes "1", so the actual production number becomes "1". Note that in Figure 8, the production unit values acquired from the node device 3 increase by 1 continuously, but depending on the interval at which the monitoring device 4 acquires the production unit values from the node device 3, the production unit values may not be continuous. Figure 9 is a diagram showing an example in which the production unit values acquired by the monitoring device 4 from the node device 3 are not continuous values, but even in this case, the actual production number is accurately counted by processing similar to that described above.

Next, in FIG. 6, the monitoring device 4 sets the variable PreVal to the value of the variable CurVal (step S9') and waits for the latest production unit value to be set (step S2').

On the other hand, if the monitoring device 4 determines that the variable CurVal is smaller than the variable PreVal (Yes in step S3'), it further determines whether the variable PreVal is greater than a predetermined threshold value that is the majority of the maximum count value (for example, when held in 18 bits, 209,714, which is 80% of 262,143) (PreVal>209,714) (step S6').

When the monitoring device 4 determines that the variable PreVal is greater than a predetermined threshold value (209,714) that is the majority of the maximum count value (Yes in step S6'), it executes a round-up process (step S7'). The round-up process is similar to that shown in FIG. 4, in which the actual production number at that time is set to the variable ProductCnt (step S71), 262,143-PreVal+CurVal is set as the increase in the production number (step S72), and ProductCnt+the increase in the production number is set as the actual production number (step S73).

For example, if the production number "1" is obtained in the third box from the right in Figure 9, the variable PreVal will be the previous value "262,120" and the variable CurVal will be "1", a round-up process will be performed, the variable ProductCnt will be the previous actual production number "52,120", the increase in production number will be "24" (=262,143-262,120+1), and the actual production number will be "52,144" (=52,120+24).

Next, in FIG. 6, the monitoring device 4 sets the variable PreVal to the value of the variable CurVal (step S9') and waits for the latest production unit value to be set (step S2').

On the other hand, if the monitoring device 4 determines that the variable PreVal is not greater than the predetermined threshold (209,714) which is the majority of the maximum count value (No in step S6'), it executes a count correction process (step S8'). The count correction process is similar to that shown in FIG. 5, in which the actual production number at that time is set to the variable ProductCnt (step S81), "0" is set as the increase in the production number (step S82), and ProductCnt + the increase in the production number "0" is set as the actual production number (step S83).

Figure 10 is a diagram showing an example of correction when the production unit figure acquired by the monitoring device 4 from the node device 3 is reduced due to a malfunction. In Figure 10, in the shaded box, when the variable CurVal becomes "0", the variable PreVal is the previous "102", a count correction process is performed, the variable ProductCnt becomes "2", which is the previous actual production number, the increase in the production number becomes "0", and the actual production number remains at "2".

Next, in FIG. 6, the monitoring device 4 sets the variable PreVal to the value of the variable CurVal (step S9') and waits for the latest production unit value to be set (step S2').

Next, the first problem in the comparative example is as follows. Figure 11 is a diagram showing an example of a defect in which an erroneous round-up process (step S7') causes a sudden increase in the actual production number. In Figure 11, assume that at the time of the fourth box from the left, the power is turned off (OFF) and then on (ON) in a short period of time in the node device 3, the production number value "210,003" in the volatile memory is written to the non-volatile memory (Flash RAM), and "210,003" is read back from the non-volatile memory (Flash RAM) to the volatile memory.

Then, between 30 [s] and 120 [s], a spontaneous reset occurred in the node device 3 due to a short power off-on, which is shown in the second box from the right. In this case, the reset causes "210,003" to be read from the non-volatile memory (Flash RAM) to the volatile memory and becomes the production number acquired by the monitoring device 4, which is smaller than the previous "210,005". In addition, since the variable PreVal "210,005" is larger than the predetermined threshold (209,714) which is the majority of the maximum count value, a round-up process (step S7') is executed. As a result, the above process causes the production number to increase from "5" to "262,146", which is close to the maximum count value (262,143).

Next, the second problem in the comparative example is as follows. Figure 12 is a diagram showing an example of a defect in which an erroneous normal count-up process (step S5') causes a sudden increase in the actual production number. In Figure 12, assume that at the time of the second box from the left, the power is turned off (OFF) and then on (ON) in a short period of time in node device 3, and the production number value "262,412" in the volatile memory is written to the non-volatile memory (Flash RAM), and "262,412" is read back from the non-volatile memory (Flash RAM).

Then, between 30 [s] and 120 [s], a spontaneous reset occurred in the node device 3 due to a short power off-on, which is shown in the fourth box from the right. In this case, the reset causes "262,412" to be read from the non-volatile memory (Flash RAM) to the volatile memory, and this becomes the production number acquired by the monitoring device 4, which is greater than the previous "1". Therefore, the normal count-up process (step S5') is executed. As a result, the above process causes the production number to increase from "3" to "262,414", which is close to the maximum count value (262,143).

Below, we will explain the general processing in the embodiment shown in Figures 2 to 5, including a processing example that solves the above problems.

In FIG. 2, at the beginning of each day, the monitoring device 4 sets the production value at the beginning of each day to the variable PreVal (step S1).

Next, when the monitoring device 4 acquires the production unit value from the node device 3, it sets the latest production unit value to the variable CurVal (step S2) and determines whether the variable CurVal is smaller than the variable PreVal (CurVal<PreVal) (step S3).

If the monitoring device 4 determines that the variable CurVal is not smaller than the variable PreVal (No in step S3), it further determines whether the value obtained by subtracting the variable PreVal from the variable CurVal is greater than a predetermined threshold value (209,714) that is the majority of the maximum count value (CurVal-PreVal>209,714) (step S4).

If the monitoring device 4 determines that the value obtained by subtracting the variable PreVal from the variable CurVal is not greater than a predetermined threshold value (209,714) that is the majority of the maximum count value (No in step S4), it executes normal count-up processing (step S5). The normal count-up processing (step S5) is as shown in FIG. 3.

When the monitoring device 4 determines that the value obtained by subtracting the variable PreVal from the variable CurVal is greater than a predetermined threshold value (209,714) that is the majority of the maximum count value (Yes in step S4), the monitoring device 4 executes a count correction process (step S8). The count correction process (step S8) is as shown in FIG. 5.

Then, after the normal count-up process (step S5) or count correction process (step S8), the monitoring device 4 sets the variable PreVal to the value of the variable CurVal (step S9) and waits for the latest production unit value to be set (step S2).

The second problem (Figure 12) mentioned above occurs because the normal count-up process is executed even though the production value has increased significantly due to a spontaneous reset of the node device 3. Therefore, in this embodiment, when the production value increases and the difference from the previous production value is greater than a predetermined threshold value (209,714) that is the majority of the maximum count value, a count correction process (step S8) is executed instead of the normal count-up process (step S5).

Figure 13 is a diagram showing an example in which the defect in Figure 12 is solved by an embodiment. In Figure 13, assume that at the time of the second box from the left, node device 3 is powered off (OFF) and then on (ON) in a short period of time, the production unit value "262,412" in the volatile memory is written to the non-volatile memory (Flash RAM), and "262,412" is read back from the non-volatile memory (Flash RAM) to the volatile memory.

Then, between 30 [s] and 120 [s], a spontaneous reset occurred in the node device 3 due to a short power off-on, which is shown in the fourth box from the right. In this case, the reset causes "262,412" to be read from the non-volatile memory (Flash RAM) to the volatile memory, and this becomes the production number acquired by the monitoring device 4, which is greater than the previous "1" (No in step S3). However, since the difference from the previous "1" (262,411) is greater than the threshold value (209,714) (Yes in step S4), the process moves to count correction processing (step S8), and the actual production number does not change from the previous "3" due to the processing in FIG. 5 described above.

Next, in FIG. 2, if the monitoring device 4 determines that the variable CurVal is smaller than the variable PreVal (Yes in step S3), it further determines whether the value obtained by subtracting the variable CurVal from the variable PreVal is greater than a predetermined threshold value (209,714) that is the majority of the maximum count value (PreVal-CurVal>209,714) (step S6).

If the monitoring device 4 determines that the value obtained by subtracting the variable CurVal from the variable PreVal is greater than a predetermined threshold value (209,714) that is the majority of the maximum count value (Yes in step S6), it executes a round-up process (step S7). The round-up process (step S7) is as shown in FIG. 4.

If the monitoring device 4 determines that the value obtained by subtracting the variable CurVal from the variable PreVal is not greater than a predetermined threshold value (209,714) that is the majority of the maximum count value (No in step S6), it executes a count correction process (step S8).

Then, after the round-up process (step S7) or the count correction process (step S8), the monitoring device 4 sets the variable PreVal to the value of the variable CurVal (step S9) and waits for the latest production unit value to be set (step S2).

The first problem (FIG. 11) described above occurs when the round-up process is executed even though the production value has decreased slightly due to a spontaneous reset of the node device 3. Therefore, in this embodiment, when the production value has decreased and the difference from the previous production value is smaller than a predetermined threshold value (209,714) that is the majority of the maximum count value, the count correction process (step S8) is executed instead of the round-up process (step S7).

Figure 14 is a diagram showing an example in which the defect in Figure 11 is solved by an embodiment. In Figure 14, assume that at the time of the fourth box from the left, node device 3 is powered off (OFF) and then on (ON) in a short period of time, the production unit value "210,003" in the volatile memory is written to the non-volatile memory (Flash RAM), and "210,003" is read back from the non-volatile memory (Flash RAM) to the volatile memory.

Then, between 30 [s] and 120 [s], a spontaneous reset occurred in the node device 3 due to a short power off-on, which is shown in the second box from the right. In this case, the reset causes "210,003" to be read from the non-volatile memory (Flash RAM) to the volatile memory and becomes the production number acquired by the monitoring device 4, which is smaller than the previous "210,005" (Yes in step S3). However, since the difference "2" from the previous "210,005" is smaller than the threshold value (209,714) (No in step S6), the process moves to count correction processing (step S8), and the actual production number does not change from the previous "5" due to the processing in FIG. 5 described above.

Figure 15 is a diagram showing an example of normal round-up processing according to an embodiment. In Figure 15, when a production number of "1" is acquired after the previous production number of "262,413" in the fifth box from the left, CurVal<PreVal (Yes in step S3) and PreVal-CurVal>209,714 (Yes in step S6), so the round-up processing (step S7) is executed. Then, as a result of the processing in Figure 4, the increase in the production number becomes "1" and the actual production number becomes "4" from the previous "3".

Although the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and various modifications are possible without departing from the spirit of the invention.

As described above, the machine monitoring system according to the embodiment includes a node device that counts the production value and stores it in a volatile memory each time it acquires a signal indicating production output from the equipment to be monitored, rounds up when it reaches a predetermined maximum count, stores the production value in a non-volatile memory when it detects that the power is off, and writes it back to the volatile memory when it is powered on, and a monitoring device that acquires the production value from the node device and manages the actual production number for each predetermined period. If the latest production value acquired from the node device is lower than the previous production value, or if the difference between the previous production value and the latest production value exceeds a predetermined threshold that is a majority of the maximum count value, the monitoring device determines that a round-up has occurred and calculates the actual production number, and performs a correction process that does not increase the actual production number if the difference between the previous production value and the latest production value does not exceed the threshold. This makes it possible to prevent an abnormal increase in the actual production number even if the node device spontaneously resets.

In addition, if the latest production value obtained from the node device is not lower than the previous production value, or if the difference between the previous production value and the latest production value does not exceed a threshold, the monitoring device calculates the actual production number using a normal count-up process, and if the difference between the previous production value and the latest production value exceeds a threshold, a correction process is performed that does not increase the actual production number. This makes it possible to prevent other inconveniences caused by spontaneous resetting of the node device from causing an abnormal increase in the actual production number.

The threshold value is 80% of the maximum count value. This allows for practical management without any inconvenience.

Also, the monitoring device acquires production unit values from a node device that counts the production unit values each time a signal indicating production output from the equipment to be monitored is acquired and stores them in volatile memory, rounds up when a predetermined maximum count is reached, stores the production unit values in non-volatile memory when power-off is detected, and writes them back to the volatile memory when power is turned on, and manages the actual production number for each predetermined period. If the latest production unit value acquired from the node device is lower than the previous production unit value, and the difference between the previous production unit value and the latest production unit value exceeds a predetermined threshold that is a majority of the maximum count value, it determines that a round-up has occurred and calculates the actual production number, and performs a correction process that does not increase the actual production number if the difference between the previous production unit value and the latest production unit value does not exceed the threshold. This makes it possible to address the issue by improving the monitoring device.

Also, a method in a monitoring device that acquires production unit values from a node device that counts the production unit values each time a signal indicating production output from the equipment to be monitored is acquired and stores them in volatile memory, rounds up when a predetermined maximum count is reached, stores the production unit values in non-volatile memory when power-off is detected, and writes them back to the volatile memory when power is turned on, and manages the actual production number for each predetermined period, in which if the latest production unit value acquired from the node device is lower than the previous production unit value, and if the difference between the previous production unit value and the latest production unit value exceeds a predetermined threshold that is a majority of the maximum count value, a round-up is determined and the actual production number is calculated, and if the difference between the previous production unit value and the latest production unit value does not exceed the threshold, a correction process is performed by the computer that does not increase the actual production number. This makes it possible to address the issue by improving the processing method in the monitoring device.

Furthermore, the present invention is not limited to the above-mentioned embodiment. The present invention also includes configurations in which the above-mentioned components are appropriately combined. Furthermore, further effects and modifications can be easily derived by those skilled in the art. Therefore, the broader aspects of the present invention are not limited to the above-mentioned embodiment, and various modifications are possible.

1 Machine monitoring system, 2 Equipment to be monitored, 3 Node device, 4 Monitoring device, 5 Firewall device, 6 Time server device, 7 Terminal device, F1 Factory, F2 Factory, AF Management office

Claims (5)

a node device that counts a production value every time a signal indicating production output from a monitored facility is acquired, stores the count in a volatile memory, rounds up when a predetermined count maximum is reached, stores the production value in a non-volatile memory when power is turned off, and writes the production value back to the volatile memory when power is turned on;
a monitoring device that acquires the production unit values from the node devices and manages the actual production numbers for each predetermined period;
the monitoring device determines that a round-up has occurred and calculates the actual production number when the latest production value acquired from the node device is lower than the previous production value and the difference between the previous production value and the latest production value exceeds a predetermined threshold value that is a majority of the maximum count value, and performs a correction process not to increase the actual production number when the difference between the previous production value and the latest production value does not exceed the threshold value.
Machine monitoring system. the monitoring device calculates the actual production number by a normal count-up process when the latest production value acquired from the node device is not lower than the previous production value and when the difference between the previous production value and the latest production value does not exceed the threshold value, and performs a correction process not to increase the actual production number when the difference between the previous production value and the latest production value exceeds the threshold value.
The machine monitoring system of claim 1 . The threshold value is 80% of the maximum count value.
3. A machine monitoring system according to claim 1 or 2. A monitoring device that acquires production unit values from a node device that counts a production unit value every time a signal indicating production output from a monitored facility is acquired, stores the production unit value in a volatile memory, rounds up when a predetermined count maximum is reached, stores the production unit value in a non-volatile memory when a power-off is detected, and writes the production unit value back to the volatile memory when the power is turned on, and manages an actual production number for each predetermined period,
When the latest production value obtained from the node device is lower than the previous production value, if the difference between the previous production value and the latest production value exceeds a predetermined threshold value that is a majority of the maximum count value, a round-up is determined and the actual production number is calculated, and if the difference between the previous production value and the latest production value does not exceed the threshold value, a correction process is performed so as not to increase the actual production number.
Monitoring equipment. A method for a monitoring device that acquires production unit values from a node device that counts a production unit value and stores it in a volatile memory every time a signal indicating production output from a monitored facility is acquired, rounds up when a predetermined maximum count is reached, stores the production unit value in a non-volatile memory when a power-off is detected, and writes the production unit value back to the volatile memory when the power is turned on, and manages an actual production number for each predetermined period, comprising:
When the latest production value obtained from the node device is lower than the previous production value, if the difference between the previous production value and the latest production value exceeds a predetermined threshold value which is a majority of the maximum count value, the computer determines that a round-up has occurred and calculates the actual production number, and if the difference between the previous production value and the latest production value does not exceed the threshold value, the computer performs a correction process not to increase the actual production number.
Monitoring methods.

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