JP7126564B2 - Device monitoring device, device monitoring method, and device monitoring program - Google Patents

Description

The present invention relates to an equipment monitoring apparatus, equipment monitoring method, and equipment monitoring program for monitoring equipment states of a plurality of equipment installed in plant facilities such as sewage treatment facilities and water supply facilities.

2. Description of the Related Art A system that uses a combination of a programmable logic controller (PLC) and a collection terminal that collects equipment status data related to the equipment status from the PLC is widely used for the purpose of monitoring the equipment status of a plurality of equipment. The device status data collected by the collection terminal is transmitted from the collection terminal to a server device or the like, and utilized for monitoring and input/output control of devices installed in the entire facility or in a predetermined area.

In such systems, the PLCs and collection terminals are typically distributed to correspond to the distributed placement of the equipment within the facility. Here, it is necessary to enable each of the distributed collection terminals to communicate with the server device or the like, but if wired wiring is used as the means for such communication, the wiring becomes complicated. . However, in order to improve the reliability of wireless communication and reduce communication costs, it is required to reduce the amount of data that is transmitted and received.

Regarding such a reduction in the amount of data, for example, Japanese Patent Application Laid-Open No. 6-95718 (Patent Document 1) discloses that it is determined whether or not there is a change between the detected data and the previously transmitted/received data. , discloses a remote I/O system in which up-to-date data is sent and received only when changes have occurred. With this technology, the amount of data that is transmitted and received when there is no change in data can be reduced, so the amount of communication associated with the operation of the system can be reduced.

Further, for example, Japanese Patent Application Laid-Open No. 2003-280732 (Patent Document 2) discloses a data transmission device configured to transmit only the state of a device whose state has changed among a plurality of devices to be monitored. It is With this technique, device states that do not change are not transmitted, so the amount of data transmitted can be reduced.

Japanese Patent Application Laid-Open No. 6-95718 Japanese Patent Application Laid-Open No. 2003-280732

However, in the techniques disclosed in Patent Documents 1 and 2, it is necessary for the server device that receives the data to compare the previous data with the latest data to identify specific changes. Therefore, when data is transmitted from a plurality of collecting terminals at the same time, the calculation load on the server increases, and there is a possibility that smooth data processing cannot be performed. It is not uncommon for equipment failures, utility status changes, processing object status changes, etc., to result in a chain reaction of equipment status changes in multiple equipment. It is not uncommon for simultaneous transmissions from

Therefore, it is desired to implement a device monitoring apparatus that can identify specific changes in device status while reducing the computational load on the server device side.

A first equipment monitoring apparatus according to the present invention includes a collection terminal for collecting equipment status data relating to equipment status from a PLC capable of executing equipment monitoring and input/output control; a server for storing the equipment status data; and the collection terminal includes a terminal storage unit for storing a device status bit string that is a bit string specifying the status of the device monitored by the PLC that is a collection target of the collection terminal; a transmitting unit for transmitting the device status data to the server when the server receives the device status data; and the server includes a receiving unit for receiving the device status data from the collecting terminal and a server storage for storing the received device status data. and a section, wherein the device status data includes change data specifying changes in the device status bit string within a predetermined period immediately before the time when the device status data is transmitted, and the device status bit string is A plurality of bits constituting the apparatus take an on state or an off state, and the device state data includes, as the change data, a bit that has changed from the off state to the on state within the predetermined period among the plurality of bits. It is characterized by including at least one of specifying on-change data and off-change data specifying a bit among the plurality of bits that has changed from the on state to the off state within the predetermined period .
A second equipment monitoring apparatus according to the present invention includes a collection terminal for collecting equipment status data relating to equipment status from a PLC capable of executing equipment monitoring and input/output control; a server for storing the equipment status data; and the collection terminal includes a terminal storage unit for storing a device status bit string that is a bit string specifying the status of the device monitored by the PLC that is a collection target of the collection terminal; a transmitting unit for transmitting the device status data to the server when the server receives the device status data; and the server includes a receiving unit for receiving the device status data from the collecting terminal and a server storage for storing the received device status data. and a section, wherein the device status data includes change data specifying a change in the device status bit string within a predetermined period immediately before the time when the device status data is transmitted; It is characterized in that the device state data that has not been received can be complemented based on the device state data stored in the storage unit.

A first device monitoring method according to the present invention is a device monitoring method in which device state data is collected by a collection terminal from a PLC capable of executing device monitoring and input/output control, and the device state data is stored in a server. a terminal storing step of storing a bit string specifying a state of the device to be monitored as a device state bit string in the collecting terminal based on a signal obtained from the PLC to acquire the state data of the device to be monitored; a communication step of causing the collection terminal to transmit the device status data when a bit string changes and causing the server to receive the device status data; and a server storage step of causing the server to store the device status data received by the server. and the device state data includes change data specifying a change in the device state bit string within a predetermined period immediately before the device state data is transmitted, and a plurality of bits forming the device state bit string. takes an ON state or an OFF state, and the device state data is ON change data specifying, as the change data, a bit among the plurality of bits that has changed from the OFF state to the ON state within the predetermined period. , and OFF change data specifying a bit that has changed from the ON state to the OFF state within the predetermined period of time among the plurality of bits .
A second device monitoring method according to the present invention is a device monitoring method in which device state data is collected by a collection terminal from a PLC capable of executing device monitoring and input/output control, and the device state data is stored in a server. a terminal storing step of storing a bit string identifying a state of the device to be monitored as a device state bit string in the collecting terminal based on a signal obtained from the PLC for obtaining state data of the device to be monitored; and the device state bit string. and a server storage step of causing the server to store the device status data received by the server. , the device status data includes change data specifying a change in the device status bit string within a predetermined period immediately before the time when the device status data is transmitted, and in the server, the device stored in the server The method further comprises a complementing step of complementing the unreceived equipment status data based on the status data.

A first equipment monitoring program according to the present invention causes a computer to execute a function of collecting equipment status data from a PLC capable of executing equipment monitoring and input/output control with a collection terminal and storing the equipment status data in a server. A device monitoring program for storing, in the collecting terminal, a bit string specifying the state of the device as a device state bit string based on a signal obtained from the PLC to obtain the state data of the device to be monitored. a communication function for causing the collecting terminal to transmit the device status data of the device when the device status bit string changes and for the server to receive the device status data; and storing the device status data received by the server in the server. a server storage function to cause a computer to execute a server storage function, wherein the device state data includes change data specifying a change in the device state bit string within a predetermined period immediately before the time when the device state data is transmitted; A plurality of bits constituting the device state bit string take an ON state or an OFF state, and the device state data is, as the change data, one of the plurality of bits that changes from the OFF state to the ON state within the predetermined period. and off-change data specifying a bit of the plurality of bits that changed from the on state to the off state within the predetermined period. Characterized by
A second equipment monitoring program according to the present invention collects equipment status data from a PLC capable of executing equipment monitoring and input/output control by means of a collection terminal, and causes a computer to execute a function of storing the equipment status data in a server. A device monitoring program, which stores a bit string identifying the state of the device as a device state bit string in the collecting terminal based on a signal obtained from the PLC to obtain the state data of the device to be monitored. a communication function for causing the collecting terminal to transmit the device status data of the device when the device status bit string changes and for the server to receive the device status data; and storing the device status data received by the server in the server. and a server storage function, wherein the device status data includes change data specifying changes in the device status bit string within a predetermined period immediately before the time when the device status data is transmitted, and the server The computer is further caused to execute a complementing function of complementing the unreceived device state data based on the device state data stored in the device.

According to these configurations, since the collecting device takes charge of the comparison operation processing between the previous device state data and the latest device state data, it is possible to detect specific changes in the device state while reducing the calculation load on the server device side. Content can be specified.

Preferred embodiments of the present invention are described below. However, the scope of the present invention is not limited by the preferred embodiments described below.

As one aspect of the device monitoring apparatus according to the present invention, a plurality of bits forming the device state bit string take an ON state or an OFF state, and the device state data is the change data, ON-change data specifying a bit that changed from the OFF state to the ON state within the predetermined period, and a bit among the plurality of bits that changed from the ON state to the OFF state within the predetermined period. specifying off-change data.

According to this configuration, changes in the device status bit string can be identified in units of bits, so the load on the server device side can be more easily reduced.

As one aspect of the device monitoring apparatus according to the present invention, it is preferable that the device state data include the ON change data and the OFF change data as the change data.

According to this configuration, it is easy to specify the ON change and the OFF change of the device status bit string in units of bits, so that the load on the server device side can be further reduced.

As one aspect of the device monitoring apparatus according to the present invention, preferably, the device state data further includes the latest device state bit string at the time the device state data is transmitted.

According to this configuration, even if the latest device status data stored in the server storage section and the latest transmitted device status data do not match due to a past communication failure or the like, Since the latest data and the immediately previous data can be restored on the server device side, it is easy to grasp the history of the device status bit string.

As one aspect of the device monitoring apparatus according to the present invention, preferably, the device state data further includes change time data specifying a time when the device state bit string changes.

According to this configuration, it is easier to grasp the history of the device status bit string.

As one aspect of the device monitoring apparatus according to the present invention, it is preferable that the transmission unit collects device state bit string data in units of words and transmits the data to the server as the device state data.

According to this configuration, even when a plurality of device status bits change simultaneously, it is easy to reduce the size of the device status data to be transmitted.

As one aspect of the device monitoring apparatus according to the present invention, the collecting terminal determines whether or not the device status bit string has changed at predetermined time intervals, and the transmission unit determines whether the device status bit string has changed in the determination. Preferably, when it is determined that the bit string has changed, the device status data are collected at predetermined transmission intervals and transmitted to the server.

According to this configuration, it is easy to reduce the number of times of transmission, and as a result, it is easy to reduce the total size of the device status data to be transmitted.

As one aspect of the device monitoring apparatus according to the present invention, it is preferable that the server is configured to complement the device state data that has not been received based on the device state data stored in the server storage unit. .

According to this configuration, it is easier to grasp the history of the device status bit string.

Further features and advantages of the invention will become clearer from the following description of exemplary and non-limiting embodiments described with reference to the drawings.

1 is a configuration diagram of a plant facility to be monitored and an equipment monitoring device according to the present invention; Example of device status bit string according to the embodiment of the present invention Example of change in device status bit string according to the embodiment of the present invention Example of equipment status data according to the embodiment of the present invention Example of server-side bit string according to the embodiment of the present invention

DETAILED DESCRIPTION OF THE INVENTION Embodiments of a device monitoring device, a device monitoring method, and a device monitoring program according to the present invention will be described with reference to the drawings. In the following, an equipment monitoring apparatus according to the present invention is applied to an equipment monitoring apparatus 1 for monitoring the equipment status of a plurality of equipment E installed in a plant facility P, and an equipment monitoring method using the equipment monitoring apparatus 1 is described. An example of application will be described. As shown in FIG. 1, the device monitoring apparatus 1 according to this embodiment includes a collection terminal 10 that collects information from PLCs 15 (programmable logic controllers) connected to a plurality of devices E, and a server 20 . A device monitoring program according to the present invention is installed in the collection terminal 10 and the server 20 . In this embodiment, devices E to be monitored include a pump, a blower, an agitator, a dehydrator, and the like.

[Configuration of collection terminal 10]
The collecting terminal 10 has an input unit 11 , a data register 12 (an example of a terminal storage unit), a collecting terminal control unit 13 and a transmitting unit 14 . The collection terminal 10 collects information from the collection target PLC 15 and monitors the device E connected to the PLC 15 . Also, one server 20 and a plurality of collection terminals 10 are configured to be able to communicate with each other. In the following description, an aggregate of a plurality of devices E connected to the PLC 15 targeted for collection by one collection terminal 10 is referred to as a device group Es.

The input unit 11 is connected to the PLC 15 and receives an input of a signal regarding an event occurring in each device E. FIG. Here, the event means that each device E switches from an operating state to a stopped state, switches from a stopped state to an operating state, or that a predetermined physical quantity (current value, rotation speed, torque, temperature, operating time, etc.) changes to a predetermined standard. This refers to the occurrence of a phenomenon such as exceeding the value range or detecting the occurrence of a failure.

The data register 12 stores a device status bit string 31 that specifies the device status of a plurality of devices E. FIG. Each bit 32 of the device status bit string 31 is assigned to various events regarding each device E. FIG. In the example shown in FIG. 2, each bit 32 of addresses "D1000.0" to "D1000.8" of the data register 12 stores the operation/stop state (address "D1000.0"), failure A The presence or absence of detection of ~ D (addresses "D1000.1" ~ "D1000.4") and the presence or absence of detection of states A ~ D (addresses "D1000.5" ~ "D1000.8") are assigned respectively. there is For example, in FIG. 2, the bit 32a of the address "D1000.0" is "0 (off state)", which stores that the device E1 is in the stopped state. Similarly, for example, the bit 32c of the address "D1000.D" is "1 (on state)", and it is stored that the state A is detected for the device E2. Here, the "state" refers to, for example, the operating mode of the device, such as automatic/manual operation, or the state in which the current value is within the standard range.

The device status bit string 31 stored in the data register 12 is changed based on the signal sent from the PLC 15 and input to the input section 11 . For example, in the state of the example shown in FIG. 2, when a signal indicating that the failure A of the device E1 has been resolved and the device E1 has started operation is input, the bit 32a of the address "D1000.0" is set to " 1" and bit 32b of address "D1000.1" changes to "0". That is, in response to the input of a signal representing the occurrence of an event in the device E connected to the collection terminal 10, each bit 32 takes an ON state or an OFF state corresponding to the signal, and the device is an array of such bits 32. Device states of a plurality of devices E are stored as the state bit string 31 .

The collection terminal control unit 13 monitors the device status bit string 31 every second (eg, at a predetermined time interval), and compares the device status bit string 31 at a certain time with the device status bit string 31 one second before. FIG. 3 shows an example in which the device status bit string 31a changes to the device status bit string 31b one second later. Specifically, in the address "D1000", the C-th bit 31d changes from the ON state to the OFF state, the 7th bit 31e changes from the OFF state to the ON state, and the 3rd bit changes from the ON state to the OFF state. is shown. If the device status bit string 31 (31b) at a certain time does not match the device status bit string 31 (31a) one second before, the collection terminal control unit 13 sets the , it is determined that the device status bit string 31 has changed.

When the collecting terminal control section 13 determines that the device state bit string 31 has changed, it generates the device state data 30 to be transmitted to the server 20 . The transmission unit 14 transmits the device status data 30 to the server 20 .

As shown in FIG. 4, the device status data 30 includes change time data 33 representing the time when the device status bit string 31 was determined to have changed, the device status bit string 31 (31b) after the change, and a change from the off state to the on state ( ON change data 34 (example of change data) specifying bits that have changed from ON state to OFF state (example of change data), and OFF change data 35 (example of change data) that specify bits that have changed from ON state to OFF state (OFF change). . The device status bit string 31, the ON change data 34, and the OFF change data 35 are expressed in word units in which the bit strings representing each data are expressed in hexadecimal, that is, in word units with a word length of 16 bits. For example, in the example shown in FIG. 4, the device status bit string 31 "0110000010110110" is represented by the hexadecimal number "60B6". Similarly, ON change data 34 is represented by hexadecimal "0080" and OFF change data 35 is represented by hexadecimal "1008".

[Configuration of server 20]
The server 20 has a receiving section 21 , a server storage section 22 and a server control section 23 . As described above, one server 20 and a plurality of collection terminals 10 are configured to communicate with each other. Therefore, the server 20 receives and stores the device status data 30 for the plurality of devices E connected to the PLC 15 that is the collection target of each of the plurality of collection terminals 10 .

The receiving section 21 receives the device status data 30 transmitted from the transmitting section 14 of the collection terminal 10 . Communication between the transmitting unit 14 and the receiving unit 21 is performed through a network such as the Internet or an intranet via a mobile phone network.

The server storage unit 22 stores the device status data 30 received by the receiving unit 21 . Here, the device state bit string 31, the ON change data 34, and the OFF change data 35 included in the device state data 30 are replaced from word units to bit units. The server storage unit 22 stores a server-side bit string 41 based on the device status data 30 that has been replaced bit by bit. In the example shown in FIG. 5, the signal IDs 1 to 16 of the server-side bit string 41 correspond to the addresses “D1000.0” to “D1000.E” of the device status bit string 31 . That is, the configuration of the server-side bit string 41 is similar to that of the device status bit string 31 . In this way, the server storage unit 22, like the data register 12 of the collection terminal 10, stores the device states and Remember that change.

The server storage unit 22 stores not only the latest server-side bit string 41 (41a) but also the past server-side bit string 41 (41b). By storing the past server-side bit string 41 in this manner, the history of the device status of a plurality of devices E can be managed.

The server control unit 23 controls communication between the collecting terminal 10 and the server 20, and based on the device state data 30 received from the collecting terminal 10 and the device state data 30 stored in the server storage unit 22, E equipment status history information can be generated. Specifically, history information is clarified by comparing the latest server-side bit string 41 with the server-side bit string 41 stored last time, and identifying bits that have changed ON and changed OFF.

However, in this embodiment, communication between the collection terminal 10 and the server 20 is performed via the mobile phone network, so it cannot be guaranteed that all the device status data 30 have been successfully received. Further, when the server 20 receives a plurality of pieces of equipment status data 30 transmitted from a plurality of collection terminals 10 at the same time or in a short period of time, a plurality of the above-described comparison processes occur at once, causing delays in such processes. An overload may cause problems in the operation of the server 20 .

Therefore, the server control unit 23 is configured to be able to identify changed bits based on the ON change data 34 and the OFF change data 35 included in the device status data 30 received from the collection terminal 10 . With this configuration, even if there is data that has not been received, the pre-change data corresponding to the device state immediately before the time when the latest device state data 30 was generated based on the ON change data 34 and the OFF change data 35 is generated. Data 42 can be generated to reveal historical information. In addition, since each collection terminal 10 is in charge of the comparison process instead of the server 20, the load of the comparison process on the server 20 can be reduced.

[Other embodiments]
Next, other embodiments of the device monitoring device, the device monitoring method, and the device monitoring program according to the present invention will be described. It should be noted that the configurations disclosed in the respective embodiments below can also be applied in combination with configurations disclosed in other embodiments unless there is a contradiction.

In the above embodiment, the device state bit string 31, the ON change data 34, and the OFF change data 35 included in the device state data 30 transmitted from the collection terminal 10 to the server 20 are represented in units of words as an example. explained. However, without being limited to such a configuration, the device status data in the present invention may be generated in units of bits.

In the above-described embodiment, the device state bit string 31, the ON change data 34, and the OFF change data 35 included in the device state data 30 are represented in units of words having a word length of 16 bits. However, without being limited to such a configuration, each piece of data included in the device status data according to the present invention does not necessarily have to be expressed in word units. In addition, when expressed in word units, one word may have a length corresponding to a number of bits commonly used in the relevant field, such as 32 bits or 64 bits.

The collection terminal according to the present invention may be a computer such as a tablet terminal or a notebook computer. Also, the PLC and collection terminal according to the present invention may be configured integrally as a PLC having a transmission function.

In the above embodiment, an example of a configuration in which the device status data 30 is transmitted from the collection terminal 10 to the server 20 via a mobile phone network has been described. However, without being limited to such a configuration, the communication path between the collection terminal and the server according to the present invention may be a known path regardless of whether it is wireless or wired.

In the above embodiment, the collection terminal 10 collects information from the PLC 15 to be collected and transmits it to the server 20, and the server 20 receives the device status data 30 and uses it as the server-side bit string 41 in the server storage unit 22. In the above description, the configuration for storing in the . However, the collection terminal and server according to the present invention can have other functional units described in the above embodiments. For example, the server according to the present invention can include a learning unit that learns the correlation between the bits representing the state of the monitored device and the bits representing the presence or absence of failure of the device based on the accumulated device state data. . According to this configuration, for example, a management value unique to the device is set based on the tendency of changes in bits representing the state of the device to be monitored (such as the amplitude of data), and the management value of the device is set based on the management value. Failure can be predicted. Note that such a learning unit may be provided in the collection terminal.

The above learning unit, for example, algorithms such as One-Class Support Vector Machine (One-Class Support Vector Machine), LOF (local outlier factor) method, IF (Isolation Forest) method, RC (Robust Covariance) method can be implemented. In addition to the history of equipment status data, when information related to the maintenance history of the equipment to be monitored is accumulated, the above learning unit is normalized based on the accumulated operating time, accumulated stop count, etc. of the equipment. An input layer that inputs the load factor of each device specified by the data and the identification information of each device specified by the individual load factor (weight factor), a single or multiple intermediate layers, and operation record data A learning unit that has learned with a teacher signal that outputs maintenance data obtained when past equipment status data is input can be configured as

Regarding other configurations, it should be understood that the embodiments disclosed in this specification are examples in all respects, and that the scope of the present invention is not limited by them. Those skilled in the art will easily understand that modifications can be made as appropriate without departing from the scope of the present invention. Therefore, other embodiments modified without departing from the gist of the present invention are naturally included in the scope of the present invention.

INDUSTRIAL APPLICABILITY The present invention can be used, for example, to monitor the equipment status of equipment in plant facilities such as sewage treatment facilities and water supply facilities.

Reference Signs List 1: equipment monitoring device 10: collection terminal 11: input unit 12: data register 13: collection terminal control unit 14: transmission unit 15: PLC
20: Server 21: Reception Unit 22: Server Storage Unit 23: Server Control Unit 30: Device Status Data 31: Device Status Bit String 32: Bits Constituting Device Status Bit String 33: Change Time Data 34: ON Change Data 35: OFF Change Data 41: Bit string on server side 42: Data before change P: Plant facilities E: Equipment

Claims (12)

a collection terminal for collecting device status data relating to the device status from a PLC capable of executing device monitoring and input/output control; and a server for storing the device status data,
The collecting terminal includes a terminal storage unit for storing a device status bit string, which is a bit string specifying the status of a device monitored by the PLC that is a target of collection by the collecting terminal; a transmitting unit configured to transmit device status data to the server;
The server has a receiving unit that receives the device state data from the collecting terminal, and a server storage unit that stores the received device state data,
The device state data includes change data specifying a change in the device state bit string within a predetermined period immediately before the device state data is transmitted,
a plurality of bits constituting the device status bit string take an on state or an off state;
The device state data includes, as the change data, on-change data specifying a bit among the plurality of bits that has changed from the off state to the on state within the predetermined period; OFF change data specifying a bit that changed from the ON state to the OFF state within a predetermined period of time . a collection terminal for collecting device status data relating to the device status from a PLC capable of executing device monitoring and input/output control; and a server for storing the device status data,
The collecting terminal includes a terminal storage unit for storing a device status bit string, which is a bit string specifying the status of a device monitored by the PLC that is a target of collection by the collecting terminal; a transmitting unit configured to transmit device status data to the server;
The server has a receiving unit that receives the device state data from the collecting terminal, and a server storage unit that stores the received device state data,
The device state data includes change data specifying a change in the device state bit string within a predetermined period immediately before the device state data is transmitted,
The device monitoring apparatus, wherein the server is configured to complement the device state data that has not been received based on the device state data stored in the server storage unit. 2. The device monitoring apparatus according to claim 1 , wherein said device state data includes said ON change data and said OFF change data as said change data. 4. The equipment monitoring apparatus according to any one of claims 1 to 3, wherein the equipment status data further includes the latest equipment status bit string at the time when the equipment status data is transmitted. 5. The equipment monitoring apparatus according to claim 1, wherein said equipment status data further includes change time data specifying a time when said equipment status bit string changed. The equipment monitoring apparatus according to any one of claims 1 to 5, wherein the transmission unit collects each data included in the equipment status data in units of words and transmits the data to the server. The collecting terminal determines whether or not the device status bit string has changed at predetermined time intervals. 7. The equipment monitoring apparatus according to any one of claims 1 to 6, wherein the equipment status data are collectively transmitted to the server. 2. The equipment monitoring apparatus according to claim 1 , wherein the server is configured to complement the unreceived equipment status data based on the equipment status data stored in the server storage unit. A device monitoring method for collecting device state data from a PLC capable of executing device monitoring and input/output control by a collection terminal and storing the device state data in a server,
a terminal storage step of storing a bit string identifying the state of the device to be monitored as a device state bit string in the collecting terminal based on a signal obtained from the PLC to obtain the state data of the device to be monitored;
a communication step of transmitting the device status data to the collecting terminal and receiving the server when the device status bit string changes;
a server storage step of storing the device status data received by the server in the server;
The device state data includes change data specifying a change in the device state bit string within a predetermined period immediately before the device state data is transmitted,
a plurality of bits constituting the device status bit string take an on state or an off state;
The device state data includes, as the change data, on-change data specifying a bit among the plurality of bits that has changed from the off state to the on state within the predetermined period; Off change data specifying bits that have changed from the on state to the off state within a predetermined period of time . A device monitoring method for collecting device state data from a PLC capable of executing device monitoring and input/output control by a collection terminal and storing the device state data in a server,
a terminal storage step of storing a bit string identifying the state of the device to be monitored as a device state bit string in the collecting terminal based on a signal obtained from the PLC to obtain the state data of the device to be monitored;
a communication step of transmitting the device status data to the collecting terminal and receiving the server when the device status bit string changes;
a server storage step of storing the device status data received by the server in the server;
The device state data includes change data specifying a change in the device state bit string within a predetermined period immediately before the device state data is transmitted,
The device monitoring method further comprising, in the server, a complementing step of complementing the unreceived device state data based on the device state data stored in the server. A device monitoring program that causes a computer to execute a function of collecting device status data from a PLC capable of executing device monitoring and input/output control with a collection terminal and storing the device status data in a server,
a terminal storage function for storing a bit string identifying a state of the device to be monitored as a device state bit string in the collecting terminal based on a signal obtained from the PLC to obtain the state data of the device to be monitored;
a communication function for transmitting the device status data of the device to the collecting terminal and receiving the server when the device status bit string changes;
causing a computer to execute a server storage function of causing the server to store the device status data received by the server;
The device state data includes change data specifying a change in the device state bit string within a predetermined period immediately before the device state data is transmitted,
a plurality of bits constituting the device status bit string take an on state or an off state;
The device state data includes, as the change data, on-change data specifying a bit among the plurality of bits that has changed from the off state to the on state within the predetermined period; OFF change data specifying bits that have changed from the ON state to the OFF state within a predetermined period of time . A device monitoring program that causes a computer to execute a function of collecting device status data from a PLC capable of executing device monitoring and input/output control with a collection terminal and storing the device status data in a server,
a terminal storage function for storing a bit string identifying a state of the device to be monitored as a device state bit string in the collecting terminal based on a signal obtained from the PLC to obtain the state data of the device to be monitored;
a communication function for transmitting the device status data of the device to the collecting terminal and receiving the server when the device status bit string changes;
causing a computer to execute a server storage function of causing the server to store the device status data received by the server;
The device state data includes change data specifying a change in the device state bit string within a predetermined period immediately before the device state data is transmitted,
A device monitoring program that further causes a computer to execute a complementing function of complementing the device state data that has not been received based on the device state data stored in the server.

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