JP2001036542A - Process control system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a process control system that can easily realize multiplexing of the system, can flexibly cope with revision of a system configuration and revision of a layout in an installation and can be operated against a communication fault. SOLUTION: A radio communication network 4 interconnects host processing units 1a, 1b and a PIO station 2. Furthermore, a multiplexed host processing unit 1a transmits a frame including a monitor status to the host processing unit 1b that is an opposite party of multiplexing for a prescribed period to conduct polling. The host processing unit 1b receiving this frame inverts its own status bit and returns the result to the host processing unit 1a.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a process control system in which a plurality of devices transmit and receive data through a network, and more particularly to multiplexing of systems.

[0002]

2. Description of the Related Art With the progress of semiconductor technology such as microprocessors and communication processing technology, in recent years factories and plants have connected equipment for measurement, control, and monitoring within the facility by a network. 2. Description of the Related Art Process control systems that automate processing and perform centralized control by exchanging data between devices via a PC have been widely used.

In this process control system, a process input / output (PIO) such as a measuring instrument, a sensor, and a display is connected via a network to form a system, and various process control processes are performed to realize automation and centralized management. I have.

[0004] In a process control system in a factory or a plant, almost 100% operation guarantee that the system does not go down from the viewpoint of safety, reliability and operation rate is required. Therefore, as a method for improving the reliability and operation rate of the system, a method is adopted in which each input / output device, the host processing device, and the network connecting them are duplicated or tripled to provide redundancy by a multiplex configuration. ing.

FIG. 10 is a diagram showing a configuration in a case where PIO stations are duplicated. FIG. 10 shows a configuration in which two systems, A and B, are used to input data from one sensor to two PIO stations 102a and 102b, and host processing is performed via wired networks 103a and 103b such as Ethernet. Device 101
a, 101b. In the configuration of FIG. 10, the PIO station 102a and the host processing device 101a
Even if the power goes down, the operator can operate the host processor 102b to operate the entire system.

[0006]

The multiplex configuration of the system which is currently performed has the following problems.
First, each host processor 101 and PIO station 10
Since the network connecting 2 is a wired connection,
When it is necessary to change the connection configuration of the system or the layout of each device in the facility, it is not easy to change the wiring. In particular, in a multiplexed system, wiring is complicated, and it is more difficult to change wiring facilities and connections.

Further, since the connection is a wired connection, the influence on the entire communication failure at a specific location is large.
If a communication failure occurs in four parts, the system B cannot be used at all.

The present invention has been made in view of the above problems, and can easily realize a multiplexed system configuration, and can flexibly respond to a change in the system configuration and a change in the layout in a facility. It is another object of the present invention to provide a process control system which is hard to be shut down due to a communication failure.

[0009]

According to the present invention, there is provided a process control system comprising: a PI for controlling a process input / output;
The wireless communication network is provided on the assumption that an O station and a host that issues instructions to the PIO station are provided. The host, PIO station, or both are multiplexed.

The wireless communication network is constituted by a plurality of wireless terminals performing wireless data communication, and each wireless terminal can communicate with all other wireless terminals via one or more other wireless terminals or directly. .

The multiplexed host and PIO station are connected to the wireless communication network. Further, the host may include a monitoring status transmitting unit and a monitoring status returning unit, and may be configured to monitor the operation of the multiplexed partner based on the monitoring status.

In the monitoring status transmitting means, the multiplexed host transmits a frame including the monitoring status to its own multiplexing partner host. In the monitoring status returning means, the host receiving the frame rewrites the monitoring status in the frame and returns the frame.

Further, the host controls the PI
A frame including the monitoring status may be transmitted to the O station to monitor the operation of the PIO station. In this case, the PIO station includes monitoring status returning means for rewriting the monitoring status in the frame and returning the frame.

[0014] The multiplexed PIO station is a multiplexed PIO station.
A monitoring status transmitting unit for transmitting a frame including a monitoring status to the O station, and a PIO station receiving the frame includes a monitoring status returning unit for rewriting the monitoring status in the frame and returning the frame. , The PIO station may monitor the operation of the PIO station multiplexed with itself.

According to the present invention, a system can be constructed simply by wirelessly connecting the host and the PIO station to the wireless communication network. Therefore, multiplexing of the host and the PIO station can be easily realized.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below. In the present invention, a wireless communication network is constructed in a facility, and the connection with each PIO station and the host processing device is connected by wireless communication.

FIG. 1 is an overall view showing a processing system according to this embodiment. The system includes one or more host processing devices 1 having a communication device and a PIO station 2.
And the relay communication device 3. Host processing device 1
And the PIO station 2 correspond to the host processor 1 shown in FIG.
The wireless communication network 4 is constructed by adding the communication function for the wireless communication network 4 to the PIO station 102 and the PIO station 102. The host processing device 1 and the PIO station 2 can communicate with the host processing device 101 and the PIO station 102 in FIG. 10 even if the communication device having the communication function is integrated with a functional part as the host processing device or the PIO station. It is good also as a structure which attaches a machine externally. Further, the relay communication device 3 is a wireless network 4
Device that has only a wireless communication function for communication with the host processor 1 and the PIO station 2 at a position that cannot be connected to the wireless network 4 or reinforces a portion where a high-quality communication path cannot be formed;
It is installed in order to form a detour of the part where the traffic inside is concentrated. Since the relay communication device 3 is installed as needed, the host processing device 1 and the PIO
This is not necessary when the network 4 can be sufficiently constructed only by the station 2.

The host processing device 1 includes the entire system and each P
It issues a control instruction to the IO station 2 and displays the measurement result and status from the PIO station 2. The operator operates the host processor 1 to control the system and manage the status. .

The PIO station 2 accesses a process input / output connected to itself and realizes functions such as power measurement. FIG. 2 is a block diagram showing a configuration example of the PIO station 2 when the wireless network communication function is integrated.

The PIO station 2 has a control CPU 2
1, a wireless unit 22 and an input / output unit 23 are connected by an internal bus 24. The control CPU 21 controls the wireless unit 2
2 based on instructions received from the host processor 1 and other PIO stations 2 and internal programs received by the input / output unit 2
3 outputs data from the sensors and measuring instruments connected to the input / output unit 23, processes the data, and transmits the data from the wireless unit 22 to the host processor 1 and other PIO stations 2. The wireless unit 22 performs wireless connection with the wireless network 4. This radio unit 22 is controlled by the control CP
It can operate independently of the U21, and even if a failure occurs in the control CPU 21 due to any failure, a frame relay process on the network 4 described later and a monitoring status from the host processing device 1 or another PIO station 2 will be described. Can be performed on a frame including. The input / output unit 23 includes a PIO station 2, a sensor, a display, an alarm, a switch,
It is used to connect to process input / output such as contact points, and to correspond to the electrical specifications of process input / output to be connected, such as digital input (DI), digital output (DO), analog input (AI), analog output (AO), etc. It is composed of multiple modules. As the input / output unit 23, generally, a plurality of devices can be connected, and the PIO station 2 having the input / output unit 23 having a configuration in which the number of connection points and types thereof are different depending on the scale of the system is used.

The wireless communication network 4 is configured by distributing a plurality of communication terminals (host processing device 1, PIO station 2, and relay communication device 3) in a specific area and connecting the communication terminals by wireless communication. You. The distance over which a wireless terminal can communicate directly is finite, and each wireless terminal cannot directly communicate with all wireless terminals constituting the system. However, since a wireless terminal can directly communicate with any of the other wireless terminals in the system, the wireless terminal performing each data transmission passes packetized data between adjacent wireless terminals, Is repeated to transfer data between arbitrary terminals. For this reason, in the wireless communication network 4, even if it is not possible to directly communicate with the destination, the data is relayed between the wireless terminals and passes through a plurality of wireless terminals, so that all wireless terminals constituting the system can communicate with each other. It has a characteristic that enables communication by using.

The surrounding environment where the system is installed is as follows:
It often changes gradually after installation, and the wireless communication path is easily affected by the environment around the installation. Therefore, the communication path set at the time of installation may disappear later, or a new communication path may occur. For this reason, the wireless communication network 4 does not use a fixed communication path, but sets a communication path according to the communication state at each time and automatically selects a relay route.

Each wireless terminal transmits information notifying its existence at a specific cycle, and notifies other adjacent wireless terminals. As a result, the arrangement of the devices is changed, and even if the communication topology changes, it is possible to cope with the change.

In the wireless communication network 4, since communication between wireless terminals is packet exchange, there is almost no restriction on the number of wireless terminals connected to the wireless communication network 4. In addition, the installation of the wireless terminal can be performed simply by placing the wireless terminal around, so that the construction cost can be reduced as compared with the construction in which a wired cable such as a telephone line is installed. Also, the price of the wireless terminal alone is low, and the maintenance of the infrastructure can be performed at a lower cost than other network systems of the same scale.

Furthermore, in the case of a network configuration using a wired connection, troubles and maintenance cannot be handled by an amateur, but in the network 4 of the present embodiment, repair and maintenance can be performed only by replacing the wireless terminal. No special staff is required. Therefore, the maintenance work is hardly required, and the operation cost is very low, so that the operation cost can be suppressed to a low level.

Further, since the network system 4 is a distributed network system and does not have a structure in which control is concentrated on a specific portion, even if a failure or a part of the wireless terminal is removed, even if a part of the network 4 is lost. The entire network does not go down, and other wireless terminals connected to the wireless communication network 4 can communicate with each other. Therefore, a system with a high operating rate can be constructed. In particular, even when some devices on the wireless communication network 4 are disconnected from the network 4 for device replacement or the like, the wireless communication network 4 itself can be operated during the processing, so that there is no need to stop other portions. .

By using the wireless communication network 4 having such characteristics for connection with each host processing device 1 and PIO station 2, the operation rate is high, and the system configuration and the layout within the facility can be changed. It is possible to construct a system which can be flexibly dealt with, is resistant to a communication failure, and can easily be multiplexed as described later.

As a method of constructing the wireless communication network 4 having such features, for example, a "wireless communication network" of Japanese Patent Application No. 10-185866 by the same applicant as the present application has been proposed. Hereinafter, the wireless communication network 4 according to the present embodiment will be described as being constructed by a technology based on a communication method based on the “wireless communication network” of Japanese Patent Application No. 10-185866. It should be noted that the wireless communication network 4 of the present invention is not limited to the wireless communication network according to this method, and may be a wireless communication network having the above-mentioned features and constructed by another method.

Next, a communication system based on the "wireless communication network" of Japanese Patent Application No. 10-185866 will be described. First, setting of a communication channel and selection of a relay route in a wireless communication network will be described.

FIG. 3 is an explanatory diagram of a method of setting a communication path between the installed wireless terminals. In FIG.
To J indicate wireless terminals distributed and installed in the area. Each of the wireless terminals A to J transmits a presence notification packet including an identifier for identifying the terminal of each transmission source at a fixed period, and the communication terminal that has received this may be able to directly communicate with this communication terminal. Recognize that.

In FIG. 3, radio terminals A, B, D, E, F
Receives the presence notification packet transmitted by the wireless terminal C, and recognizes that it has a possibility of directly communicating with the wireless terminal C. Similarly, the wireless terminals F, G,
By receiving the presence notification packet transmitted by the wireless terminal I, H and J recognize that they have a possibility of directly communicating with the wireless terminal I.

As described above, each of the wireless terminals A to J transmits the presence notification packet at a fixed period, and the adjacent wireless terminals receive the packet, whereby the direct communication according to the radio wave propagation state at that time is performed. Can recognize each other.

Next, each wireless terminal transmits a communication path diagnostic packet, diagnoses the reliability of the communication path between the wireless terminals having the possibility of direct communication recognized by the presence notification packet, The one having reliability is set as an effective communication path.

After that, each wireless terminal stores system configuration information in order to recognize through which wireless terminal having a direct communication path with all the other wireless terminals constituting the system. To send a presence notification packet.

The system configuration information is information on the relationship between the number of times of communication from the terminal and the receiving terminal. Each terminal holds, together with the system configuration information for itself, the system configuration information of an adjacent wireless communication terminal capable of direct communication. ,to manage.

FIG. 4 shows system configuration information of the wireless terminal A when the network configuration has a topology as shown in FIG. The system configuration information in FIG. 4 shows the relationship between each destination wireless terminal and the minimum number of communication times to reach the wireless terminal when a network line having a topology as shown in FIG. 5 is set. ing. The number of times of communication (the number of hops) here indicates the number of times that a packet transmitted by the wireless terminal A, which is the transmission source, is communicated between the wireless terminals before reaching the destination wireless terminal. From the system configuration information, it can be understood that there are B, C, and D in the wireless terminals to which the wireless terminal A can transfer the packet in one communication.
In addition, it can be seen that wireless terminals that require at least two times of communication to transfer a packet including the communication by the relay wireless terminal include E and F. Similarly, G, H, and I have at least 4 for wireless terminals requiring at least 3 communications.
It can be seen that J is present in the wireless terminal that requires communication twice.

Each wireless terminal stores the system configuration information as shown in FIG. 4 in the presence notification packet in the idle state and transmits it to the adjacent wireless terminal at regular intervals. Then, it updates its own system configuration information based on the system configuration information received from the adjacent wireless terminal.

Each wireless terminal holds and manages system configuration information of an adjacent wireless terminal in addition to its own system configuration information. FIG. 6 is managed by the wireless terminal A in FIG.
The configuration information of the wireless terminals B, C, and D in which the wireless terminal A has a direct communication path is shown. The wireless terminal A includes, in addition to its own system configuration information shown in FIG. 4, the wireless terminals B, C,
D also manages the system configuration information.

As a communication example using the system configuration information, a case is considered where wireless terminal A sends a packet to wireless terminal E. Referring to the system configuration information in FIG. 6, it can be seen that a packet can be transferred from the wireless terminal B to the wireless terminal E in one communication. Similarly,
It can be seen that the transfer can be performed once from the wireless terminal C and twice from the wireless terminal D. As a result, the wireless terminal A sends a packet whose destination is the wireless terminal E to either the wireless terminal B or C. The wireless terminal B or C that has received the packet from the wireless terminal A sends the packet to the wireless terminal with the least number of communication with the destination of the packet from the system configuration information held and managed by itself,
Thereafter, by the same processing, the packet is relayed in the network and reaches the destination wireless terminal.

By using such a wireless communication network, new installation of a wireless terminal, loss due to failure or withdrawal,
Even if a change occurs in the communication topology due to a change in location, each wireless terminal can respond flexibly to the change with the presence notification packet transmitted periodically, and a communication failure occurs in the set communication path. However, since another detour is set based on the system configuration information held and managed by each wireless terminal, the system has a high operation rate even with a communication failure.

Next, multiplexing of systems by the wireless network 4 will be described. FIG. 7 is a diagram illustrating an example in which the host processing device 1 is duplicated using the wireless communication network 4. In FIG. 7, two host processing devices 1a are used as host processing devices for controlling the PIO station 2-1.
And 1b. In order to construct this configuration, it is only necessary to newly install the host processing device 1b in addition to the already installed host processing device 1a and connect the host processing device 1b to the wireless communication network 4 without special wiring processing. Further, in order to achieve the triple operation, it is only necessary to install a new host processing device 1 and connect it to the wireless communication network 4. The installation position may be any position as long as it can be wirelessly connected to any of the wireless terminals constructing the wireless communication network 4, and the installation position can be moved.

For the multiplexed host processor 1, P
The IO station 2-1 is normally connected to the host processor 1a.
When the operator determines that an error has occurred in the host processing device 1a due to a hardware error, a hang-up of an application, or the like, the host processing device 1a is changed to the host processing device 1b and processing is continued. . As described above, since both the host processing apparatuses 1a and 1b can intercept the information of the entire system via the wireless communication network 4, even if an abnormality occurs in the host processing apparatus 1, another multiplexed operator is required. Host processing unit 1
By moving to, business can be continued.

FIG. 8 is a diagram showing an example in which the PIO station 2 is duplicated using the wireless communication network 4.
FIG. 8 shows an example in which the input / output of each sensor connected to the PIO station 2a is also connected to the PIO station 2b to be duplicated.

In this case, as in the case of the duplexing of the host processor 1 in FIG. 7, in order to construct a configuration in which the PIO station 2 is duplicated, it is necessary to use the same sensor as the PIO station 2a already installed. It is only necessary to provide the PIO station 2b in which inputs and outputs are connected in parallel, and to connect to the wireless network 4 without special wiring processing. Further, in order to achieve the triple operation, it is only necessary to install a new PIO station 2 and connect to the wireless communication network 4.

For the multiplexed PIO station 2, the host processor 1 normally operates the PIO station 2a.
Is used to collect data from each sensor, and when an abnormality occurs in the PIO station 2a, the PIO station 2b
To continue the business.

At this time, it is also possible to adopt a configuration in which the wireless network 4 automatically switches, instead of the operator intentionally switching from the host processing device 1. For example, even if a frame is transmitted from the host processing device 1 to the active PIO station 2a, the transmission frame is transmitted to the host processing device 2a.
Or if there is no response to the transmission frame, the transmission frame may be automatically retransmitted to the standby PIO station 2b.

As described above, in the present embodiment, the duplex system can be easily constructed by the wireless network 4. The network connection of the dual system is the same as that of the duplex system. Therefore, the use of the wireless network 4 makes it possible to easily construct the system.

In the present embodiment, the host processing device 1 transmits a frame at a specific period to the multiplexed partner and performs polling, and each host processing device 1 operates normally within the communication frame. A monitoring status area indicating whether or not the monitoring status has been provided is provided, and a function of detecting an abnormality of a multiplexed partner by monitoring a change in the monitoring status is provided.

FIG. 9 is a sequence diagram showing a monitoring process based on the monitoring status of the multiplexed host processing devices 1. The figure shows a duplicated host processing device 1
An example is shown in which a frame including a monitoring status is transmitted between two host processing devices 1 and 1b and the status is monitored with each other to monitor a multiplexed partner. Although FIG. 9 shows an example of duplexing, the same can be realized for more than tripled printing by increasing the number of corresponding status bits in the monitoring status described later and performing polling.

The host processor 1 transmits a frame to another host processor 1 or PIO station 2 at a specific period, receives a response frame to the frame, and performs polling. In this embodiment, 500 ms
In this example, a frame is transmitted from the host processing device 1a to the host processing device 1b every time.

In the figure, the monitoring status is included in the host processing device 1b, which is duplicated with itself, from the processing unit that issues a control instruction to the system and each PIO station 2 to the communication unit that performs processing as the wireless network 4. Send an SP command to send a frame. In this figure, this frame is preceded by “SP” indicating the type of the frame, followed by an ID value indicating the transmission destination, the number of bytes of data to be added to the frame, and “D” indicating that the frame is a requested frame. EOT indicating the end of transmission at the end
The code is stored.

The communication unit of the host processor 1a that has received the frame transmits, to the wireless network 4, a frame in which a data area of the size specified by the data byte number area in the frame is provided before the EOT code of the frame. Send.
This data area is a variable length area of a maximum of 128 bytes and has an area for storing the monitoring status therein. FIG.
In the case of (1), a 1-byte monitoring status is provided at the head of the data area. The remaining area in the data area may be used for another communication purpose or may store monitoring / control information.

The monitoring status is a set of status bits for monitoring the status of the host processor 1, and each bit in the monitoring status corresponds to each host processor 1. In this case, bit 0 is the host processor 1a.
Is the status bit of the host processor 1b. Among them, the status bit of the host processing device 1b corresponding to the destination of the frame has already been set to a value (FIG. 9).
In this case, '1') is set, and the processing unit of the host processing device 1a stores this value. In the status bit corresponding to the transmission source, a value (“0” in FIG. 9) obtained by inverting the value in the previous monitoring status exchange with the host processing device 1b is set.

The communication unit of the host processing device 1b that has received this frame from the wireless network 4 sends this to the processing unit as an RP result. The processing unit extracts the monitoring status from this frame. And the host processing device 1a
Is the inverted status bit value in the frame received immediately before, the host processor 1b confirms that the host processor 1a is operating normally. Then, it generates a frame including the monitoring status with its status bit inverted, and sends it to the communication unit as an SP command. In this figure, this frame is prefixed with “SP” as a frame type, followed by an ID value indicating a destination, the number of bytes of data to be added to the frame, and “I” indicating a response frame. , A data area including a monitoring status, and finally an EOT code indicating the end of transmission.

When the communication unit receives the SP command from the processing unit, the communication unit converts the SP command into a data packet and outputs the data packet to the wireless network 4.
Pour into If the radio unit does not receive a response from the processing unit within a certain time after receiving the frame including the monitoring status,
As a time-out process, a frame including the same monitoring status as the received frame is returned to the host processing device 1a.

The communication unit of the host processing device 1a that has received the reply frame from the host processing device 1b sends this to the processing unit as an RP result. The processing unit fetches the monitoring status from this frame and compares it with the value of the monitoring status stored in the transmission frame to determine whether the multiplexing partner host processing device 1b is operating normally.
If the status bit corresponding to the host processing device 1b in the received frame is an inverted value of the value in the transmission frame, it indicates that the host processing device 1b is operating normally, and if the value is the same as the value in the transmission frame. Host processing device 1
It is determined that an abnormality such as a hardware error or a hang-up of the application has occurred in the processing unit b. If there is no response from the host processing device 1b, it means that the host processing device 1b has some sort of abnormality in the communication unit.

As described above, the host processing device 1 performs polling processing on a multiplex partner with a frame including a monitoring status, thereby monitoring whether the multiplex partner is operating normally. Also, a multiplexing system based on the master-slave method or majority logic can be easily constructed by using this monitoring status. In the above example, the host processor 1a monitors the host processor 1b, which is the multiplexing partner of the host processor 1a. However, a status bit corresponding to the PIO station 2 is provided in the monitoring status, and the host processor 1a performs control by itself. The PIO station 2 may be polled to monitor whether the PIO station 2 is operating normally. Further, the configuration may be such that polling is performed not only between the host processing apparatuses 1 but also between the multiplexed PIO stations 2 and monitored.

[0058]

According to the present invention, a multiplexed system can be easily constructed by using a system using a wireless network, and even if the system has been constructed once, the configuration can be changed or the installation position of the equipment in the facility can be changed. A process control system that can flexibly respond to changes can be constructed.

Further, since the construction of the network is only required to place the wireless terminal around, the construction cost can be reduced as compared with a case where a wired cable is provided. Also, the price of the wireless terminal alone is low, and the maintenance of the infrastructure can be performed at a lower cost than other network systems of the same scale.

Furthermore, when multiplexing is performed on an already constructed system, if a cable is installed, the location and space of the installation are restricted. However, in the present invention, since a wireless network is used, only a wireless terminal is used. , There are fewer restrictions for multiplexing than wired connections.

Further, in the present invention, repair and maintenance can be performed only by replacing the wireless terminal, so that the network can be easily repaired and the maintenance work is hardly required. Further, since no special specialist for maintenance and management is required, the operation cost can be reduced to a low level.

In the network system used in the present invention, even if a communication failure occurs in a part of the network, the whole network does not go down. Furthermore, even when some devices on the wireless communication network are disconnected from the network for replacement of devices, the wireless communication network itself can be operated during the processing, so that there is no need to stop the system. Therefore, a system with a high operation rate can be constructed.

[Brief description of the drawings]

FIG. 1 is an overall view illustrating a process processing system according to an embodiment.

FIG. 2 is a diagram illustrating a configuration of a PIO station.

FIG. 3 is a diagram illustrating a situation where wireless terminals C and I transmit a presence notification packet.

FIG. 4 is a diagram showing system configuration information of a wireless terminal A;

FIG. 5 is a diagram illustrating an example of a topology of a wireless communication network.

FIG. 6 is a diagram illustrating configuration information of wireless terminals B, C, and D having a direct communication path with the wireless terminal A, which is managed by the wireless terminal A.

FIG. 7 is a diagram illustrating an example in which a host processing device is duplicated using a wireless communication network.

FIG. 8 is a diagram illustrating an example in which PIO stations are duplicated using a wireless communication network.

FIG. 9 is a sequence diagram illustrating a monitoring process based on a monitoring status between duplicated host processing devices;

FIG. 10 shows a PIO in a conventional process control system.
FIG. 3 is a diagram illustrating a configuration in a case where stations are duplicated.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1, 101 Host processing apparatus 2, 102 PIO station 3 Relay communication device 4 Wireless communication network 21 Control CPU 22 Wireless part 23 Input / output part 24 Internal bus 103 Wired network

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yoshiyuki Saito 1-1, Tanabe-Nitta, Kawasaki-ku, Kawasaki-shi, Kanagawa Prefecture Inside Fuji Electric Co., Ltd. (72) Inventor Takaaki Hatakeuchi 1, Tanabe-Nitta, Kawasaki-ku, Kawasaki-shi, Kanagawa Prefecture No. 1 Fuji Electric Co., Ltd. F term (reference) 5H209 AA01 AA05 BB01 CC01 CC07 CC13 DD11 GG11 SS01 SS04 SS07 TT01 5K033 AA06 AA09 BA08 CA01 DA01 DA17 EA03 EA07 5K048 AA00 AA07 BA23 DC01 EB10 EB12 FA01 GA03 GA12

Claims (5)

[Claims] 1. PI for controlling process input / output
In a process control system including an O station and a host that issues an instruction to the PIO station, the process control system includes a plurality of wireless terminals that perform wireless data communication, and each of the wireless terminals is connected via one or more other wireless terminals or directly. A process control system, comprising: a wireless communication network capable of communicating with all other wireless terminals; and a multiplexed host connected to the wireless communication network. 2. The multiplexed host, a monitoring status transmitting means for transmitting a frame including a monitoring status to its own multiplexing destination host, and a host receiving the frame includes: 2. The process control system according to claim 1, further comprising monitoring status returning means for rewriting the monitoring status and returning the frame. 3. The monitoring status transmitting means also transmits the frame to a PIO station controlled by its own host, and the PIO station receiving the frame rewrites the monitoring status in the frame to update the frame. The process control system according to claim 2, further comprising a monitoring status return unit that returns a response. 4. A PI for controlling process input / output
In a process control system including an O station and a host that issues an instruction to the PIO station, the process control system includes a plurality of wireless terminals that perform wireless data communication, and each of the wireless terminals is directly or via one or more other wireless terminals. A wireless communication network capable of communicating with all other wireless terminals; and a multiplexed P connected to the wireless communication network.
A process control system, comprising: an IO station. 5. The multiplexed PIO station includes: a monitoring status transmitting unit that transmits a frame including a monitoring status to a multiplexing partner PIO station; and a PIO station that receives the frame includes: 5. The process control system according to claim 4, further comprising a monitoring status returning means for rewriting the monitoring status in the frame and returning the frame.