JP2004221905A - Method for monitoring network system, monitoring system, repeater, and monitoring device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a network system monitoring method for easily recognizing to which repeater a slave connected to the downstream side of the repeaters belongs, in a network system including repeaters. <P>SOLUTION: At least one repeater 30 is connected between a master unit 12 and a slave 20 to constitute the network system. The master unit 12 issues a status read command to the slave 20. The slave 20 receiving the status read command returns a response to the master unit 12. In repeating the response, the repeater adds specific information for specifying the repeater itself to the response. A device acquiring the response recognizes connection relation between the slave 20 and the repeater from the contents of the specific information stored in the response and monitors the constitutional information of the network. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a monitoring method and a monitoring system for a network system, and a repeater and a monitoring device.
[0002]
[Prior art]
PLC (programmable controller) used in factory automation (FA) inputs ON / OFF information of input devices such as switches and sensors, and performs logical operations according to a sequence program (user program) written in a ladder language or the like. Execute. The PLC is controlled by outputting ON / OFF information signals to output devices such as relays, valves and actuators in accordance with the obtained calculation results.
[0003]
As one form of such a PLC, there is a type in which a plurality of units generated for each function are prepared and electrically and mechanically connected. There are various units such as a power supply unit, a CPU unit, an I / O unit, and a master unit as units for configuring such a type.
[0004]
The master unit is connected to a control network and can communicate with various slaves connected to the control network via the control network. An example of this type of slave is a remote IO. That is, the input devices and output devices described above may be connected to the I / O units constituting the PLC, but if all the input / output devices are directly connected to the I / O units, the input / output devices may be connected to the input / output devices. The number of wirings connecting the I / O unit to the I / O unit is the same as the number of input / output devices, and such a large number of wirings are routed inside the factory starting from the PLC (I / O unit). .
[0005]
Therefore, a remote IO serving as a terminal block for connecting input / output devices is installed near the control target, and various input / output devices are connected to the remote IO. Then, each remote IO is connected to a network cable connected to a PLC (master unit). Then, I / O data is transmitted and received between each remote IO and the PLC through master-slave communication or the like, and information is transmitted to actual input / output devices via the remote IO. I have.
[0006]
By the way, in order to monitor the configuration of a network system including slaves such as remote IOs connected via a network as described above, for example, DeviceNet (registered trademark) which is a form of a control network is connected to a network. A function is provided to monitor the master and slave node numbers and models using software on a personal computer. FIG. 1 shows an example of a monitor screen displayed by the monitoring function. As shown in this drawing, each slave is arranged in the order of node addresses, for example, # 00, # 01, # 02,....
[0007]
As a display device for displaying the configuration of a network system to which a plurality of PLCs are connected, for example, there is a “communication data display device and method, storage medium” disclosed in Patent Document 1. Also in this Patent Document 1, as shown in FIG. 6 and the like of the publication, the PLCs constituting the network are displayed in a state where they are arranged in the order of node addresses.
[0008]
An apparatus that creates a network configuration diagram in consideration of the connection relationship of network devices such as a computer and a printer connected to the network, but is not an FA network, and displays the network configuration on a monitor is disclosed in Japanese Patent Application Laid-Open No. H10-163,086. Network Configuration Display Method and System ". In this patent document 2, a network relay device having a plurality of connection ports is arranged at a predetermined position on a network, and each network device is connected to a network via the network relay device. The network relay device has information about a device connected to itself such as a so-called “hub”. Therefore, the management computer uses the network relay device to collect the connection status of the network devices, and when displaying the objects of the network relay device and the network device on the display screen, associates the predetermined objects with each other in accordance with the collected connection status. By making the connections, a network configuration diagram is created.
[0009]
[Patent Document 1]
JP-A-11-154004
[Patent Document 2]
JP 2001-308873 A
[0010]
[Problems to be solved by the invention]
In an FA system, a device called a repeater is mounted on a network, and a master unit and a slave sometimes transmit and receive data via the repeater. In other words, if the communication lines that make up the network are long, the signal level will be low, and noise will be easy to get on, so that the waveform will be disturbed. Therefore, there is a problem that accurate information cannot be transmitted. In order to solve such a problem, by disposing a repeater for shaping a waveform called a repeater at an appropriate position, the disturbed waveform is corrected to a 1/0 clear pulse waveform, and the transmission distance is lengthened. ing. In addition to increasing the transmission distance in this way, for example, connecting a plurality of slaves under a repeater in a case where a plurality of slaves that control the same device are managed as one group There is also. Note that this repeater has a function of shaping the waveform of a signal input from one side and outputting it to the other side, but does not have the function of a relay device such as a hub described in Patent Document 2.
[0011]
Therefore, for example, slaves having different numbers such as slaves # 0, # 3, # 7, and # 21 are connected to the repeater A, and slaves # 2, # 8, # 9, and # 31 are connected to the repeater B. If the network configuration is monitored for the network system using the invention disclosed in Patent Document 1, the slaves are arranged in the order of the node addresses, and the association between the slave and the repeater cannot be monitored. For this reason, when the number of nodes is large, there is a problem that it is not possible to grasp which device the slave is using even by looking at the configuration displayed on the personal computer.
[0012]
On the other hand, aside from whether the invention disclosed in Patent Document 2 can be directly applied to an FA system, a relay device such as a hub is provided in place of a conventional repeater, and information of a slave connected downstream of the relay device is stored. By storing and holding the information of the slaves held by the relay device, a specific network configuration can be known. However, adopting such a configuration causes information related to the relay device to be held only for monitoring, so that the cost of the relay device is increased and is not practical.
[0013]
The present invention makes it easy for a network system including a repeater to determine which repeater a slave connected downstream of a repeater is located downstream of without having the repeater itself hold information of a slave connected downstream. It is an object of the present invention to provide a network system monitoring method, a monitoring system, a repeater, and a monitoring device that can be recognized.
[0014]
[Means for Solving the Problems]
A monitoring method for a network system according to the present invention is a monitoring method for a network system including a configuration in which at least one repeater is interposed between a master and a slave, wherein the master issues a status read command to the slave. The slave that has received the status read command returns a response to the master, and the repeater, when relaying the response, adds identification information identifying itself to the response, The device that has obtained the information recognizes the connection relationship between the slave and the repeater based on the presence or absence of the specific information stored in the response and the content thereof, and monitors the network configuration information.
[0015]
The monitoring system according to the present invention is a monitoring system in a network system including a configuration in which at least one repeater is interposed between a master and a slave, wherein the master issues a status read command to the slave. When the slave receives the status read command addressed to itself, the slave has a function of returning a response to the master, and the relay repeats the response when relaying the response. The device that has a function of adding specific information for specifying the response, recognizes the connection relationship between the slave and the repeater from the presence or absence of the specific information stored in the response and the content thereof, and It has a function to output configuration information to output means. It was. The master may constitute, for example, a programmable controller, and the device may be a monitor device connected to the programmable controller. Of course, the device may be a programmable controller such as a master.
[0016]
Furthermore, the repeater of the present invention is a repeater that is mounted between a master and a slave that constitute a network system, and that relays data transmitted between the master and the slave, wherein the repeater issues a status read command issued from the master. When the received slave relays a response returned to the master, the slave is provided with a function of adding identification information identifying itself to the response.
[0017]
Still further, the monitor device of the present invention includes a configuration in which at least one repeater intervenes between a master and a slave, and the repeater receives a status read command issued from the master, and the slave receives the status read command from the master. Is a monitoring device for monitoring configuration information of a network system having a function of adding specific information for identifying itself to a response when relaying a response returned to the network. Then, while acquiring the response returned by the slave, the function of analyzing the content and the presence or absence of the specific information stored in the response determine whether the slave is connected under a predetermined repeater. A function for recognizing the connection relationship between the slave and the repeater by determining from which repeater the slave is connected based on the content of the specific information, and a function based on the recognized connection relationship. A function of outputting network configuration information to an output unit.
[0018]
The output unit is a display device in the embodiment, and such a configuration is preferable. However, the present invention is not necessarily limited to the display device, and may be a printing device, a storage device, a communication device, or the like. It can be realized by various things.
[0019]
Although the specific information is the node address of the repeater in the embodiment, the present invention is not limited to this, and various types such as a serial number and other ID numbers provided in the repeater and a logical name may be used. it can.
[0020]
A slave connected below the repeater always sends a response returned by the slave through the repeater before reaching the master. Therefore, the response is provided with specific information for specifying the repeater. Conversely, if there is a slave that directly communicates with the master without passing through the repeater, such specific information is not added to the response.
[0021]
Therefore, it can be determined whether or not the slave goes through the repeater based on the presence or absence of the specific information. Furthermore, when the specific information is included, it is possible to know under which repeater the slave is connected by recognizing the content of the specific information. Therefore, the connection relationship between the slave and the repeater can be known. Further, even when the number of nodes is large, the target slave can be easily found by grouping by inserting repeaters at appropriate positions.
[0022]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 2 shows an example of a network system including a repeater to which the present invention is applied. As shown in FIG. 2, the PLC 10, the various slaves 20, and the repeater 30 are connected via a field bus 40 to form a network system. The slave 20 includes a remote IO and other devices. The slave 20 may be directly connected to the field bus 40 connected to the PLC 10, or may be connected to the field bus 40 a connected to the repeater 30 and communicate with the PLC 10 via the repeater 30. . A terminating resistor 41 is connected to the ends of the field bus 40 and the field bus 40a.
[0023]
Although the repeater 30 is also provided with a node address and is a kind of slave in a broad sense, the slave 20 in the present embodiment means a device having a function for controlling the FA system, It is separated from the repeater 30 that relays data transmitted through the bus 40 and the like. In the example shown in FIG. 2, only the slave 20 is connected downstream of the repeater 30. However, another repeater is arranged downstream of the repeater 30. Of course, there may be a form in which a plurality of repeaters 30 exist between the PLC 10.
[0024]
Further, a personal computer 42, which is a monitor / setting tool, is connected to the PLC 10 to collect and monitor information on each device connected to the network via the PLC 10, and to download programs to the PLC 10, the slave 20, and the like. And data settings.
[0025]
The PLC 10 is configured by connecting units generated for each function, and includes, for example, a CPU unit 11, a master unit 12, and the like. The master unit 12 is connected to the field bus 40 and communicates with each slave 20 and the repeater 30. Further, the CPU 10 accesses the IO memory of the CPU unit 11 via the internal bus of the PLC 10 to read and write IO data and the like.
[0026]
In addition, a personal computer 42 as a monitor device connected to the PLC 10 is connected to the CPU unit 11 in the example of FIG. However, the present invention is not limited to this. The connection may be made via a network. Further, the connection may be made to the master unit 12 or to a special function unit provided on the field bus 40. it can.
[0027]
As shown in FIG. 3, the master unit 12 is connected to a field bus and communicates with the communication interface 12a that actually transmits and receives data. The master unit 12 performs master-slave communication via the communication interface 12a. ASIC 12b for transmitting / receiving I / O data to / from, transmitting a predetermined command, and receiving a response based on the command, an MPU 12d for performing various controls, and a work area when executing various controls. RAM 12c, an EEPROM 12e storing a program for performing the above control, various setting data, and the like; an interface 12h for communicating with other units (for example, a CPU unit); an operation state (communication state); LED display section 12f indicating abnormality / normality and address And a setting switch 12g for performing such as a constant.
[0028]
As control performed by the MPU 12d, the MPU 12d communicates with the CPU unit 11 and other units, and operates the master ASIC 12b. Particularly in the context of the present invention, a status read request is received from the personal computer 42 received via the CPU unit 11, a status read command is sent to the slave 20 connected to the network, and a response from the slave 20 is sent. Upon receipt, it has a function of analyzing it and returning it to the personal computer 42 via the CPU unit 11. At this time, since the command handled by the CPU unit 11 or the personal computer 42 and the command handled by the repeater 30 or the slave 20 are different, the conversion processing is appropriately performed by the master unit 12. Note that the basic hardware configuration and the like are the same as those of the conventional master unit, and a detailed description thereof will be omitted.
[0029]
As shown in FIG. 4, the slave 20 is connected to a field bus and communicates with the master unit 12 by actually transmitting and receiving I / O data and various messages, and via the communication interface 20a. The obtained master-slave communication, transmission and reception of I / O data, reception of a predetermined command, and transmission of a response based on the command, an ASIC for slave 20b, an MPU 20d for performing various controls, and the above-described control An EEPROM 20e storing programs, various setting data, IO data, etc., an I / O unit 20j for connecting to an I / O device and transmitting / receiving I / O data, an operation state (communication state), and an abnormal / normal state LED display unit 20f for indicating the status and the like, and a setting switch 20g for setting a node address and the like. That. Further, a power supply unit 20i that reduces the input voltage (24V) to 5V and supplies power to each element in the slave 20 is provided.
[0030]
In relation to the present invention, the slave 20 has a function of analyzing a status read command sent from the master unit 12 and issuing a response and returning it to the master unit 12 when addressed to itself. Therefore, when the master unit 12 and the personal computer 42 issue the status read command to a certain node address, if there is a response, the slave of the node address exists, and if there is no response, the slave of the node address does not exist. The node address of the slave 20 connected to the network can be known. Note that the configuration, operation, and effect of the slave 20 are the same as those of the conventional one, and a detailed description thereof will be omitted.
[0031]
The repeater 30 has communication interfaces 31 and 32 connected to the master side and the slave side, respectively, as shown in FIG. 5, and is mounted between the two communication interfaces 31 and 32 to transmit a predetermined data (signal). An ASIC for a repeater 33 for performing processing is provided. Further, the power supply unit 34 includes a power supply unit 34 that reduces the input voltage (24 V) to 5 V and supplies power to each element in the repeater 30. Further, an LED display unit 35 for indicating an operation state (communication state) and an abnormal / normal state and a setting switch 36 for setting a node address are provided.
[0032]
Further, the ASIC 33 for a repeater basically has a function of adjusting the waveform of a transmitted signal (disturbed), restoring it to a beautiful 1/0 digital signal, and outputting the digital signal. This function is a basic function of a conventional repeater, and a description of a specific configuration and processing procedure will be omitted.
[0033]
In the present invention, as a function of the repeater ASIC 33, when data is received from the master-side communication interface 31, the above-described waveform shaping is performed and the data is transferred to the slave-side communication interface 32. When data (response) is received from the slave-side communication interface 32, the above-described waveform shaping is performed, and after adding its own node address to the response, the response is passed to the master-side communication interface 31. . Further, when passing through a plurality of repeaters 30, the node addresses of the repeaters 30 are added in the order of passing (for example, always added at the end).
[0034]
As a result, in the case of the slave 20 that directly transmits and receives data to and from the master unit 12 without the intervention of the repeater 30, the response issued to the status read command reaches the master unit 12 without passing through the repeater 30, The node address of the repeater 30 is not given to the response. On the other hand, in the above-mentioned response issued from the slave 20 on the downstream side of at least one or more repeaters 30, the node address of the repeater 30 is added when passing through the repeater 30. Therefore, the master unit 12 and the personal computer 42 determine whether the slave 20 is directly connected to the field bus 40 connected to the master unit 12 based on whether or not the acquired response includes the node address of the repeater 30. In addition, when connected below the repeater 30, the network configuration such as which repeater 30 is connected can be recognized from the node address.
[0035]
Then, in order to monitor the network configuration, the personal computer 42 as a monitoring device acquires the connection status of each device (slave 20, repeater 30) configuring the network via the PLC 10 and displays it on the display device 42a. That is, the personal computer 42 is connected to the CPU unit 11 and communicates with the CPU unit 11. Therefore, the personal computer 42 can know the network configuration based on the obtained response, for example, by sequentially requesting the status read from the node having the node address # 0.
[0036]
Specifically, the entire network system performs monitoring by performing communication according to the flowchart shown in FIG. FIG. 7 shows a data flow (timing chart) between the respective devices at that time. That is, first, the personal computer 42 requests a status read from the next node (ST1). That is, in the case of a network system in which node addresses are assigned from # 0 to #N, first, a status read request is made to the node # 0 and a response is received or when a timeout occurs, the node # 1 is sent to the node # 1. Request a status read. Thereafter, the process is repeatedly executed in order up to #N while increasing the node address values one by one. Such processing is performed in step (1) shown in FIG.
[0037]
Next, the status read request issued from the personal computer 42 is output to the field bus 40 via the CPU unit 11 and the master unit 12, and received by the slave 20 directly or via the predetermined repeater 30 (ST2). Such processing is performed in steps (2) to (5) in FIG. Note that the example shown in FIG. 7 shows a standard example. If the repeater 30 does not exist before the slave 20, the process (4) is omitted, and a plurality of repeaters exist. In this case, the process of step (4) is executed a plurality of times.
[0038]
Then, when the slave 20 having the desired node address specified in step (1) receives the status read command and confirms that the command is addressed to itself, it returns its own status information (issues a response) (ST3). . Such processing is performed in step (5) shown in FIG.
[0039]
This response is transmitted over the network. Then, when the signal passes through the repeater 30 (Yes in ST4), the repeater 30 adds its own address to the response (ST5). Therefore, when the repeater 30 no longer exists with the master unit 12 (No in ST4), the repeater 30 is received by the master unit 12 as it is, and the received response is given to the personal computer 42 via the CPU unit 11. (ST6).
[0040]
Accordingly, the personal computer 42 analyzes the acquired response, and recognizes whether or not the node address of the repeater 30 is included in the response, and if so, recognizes the specific number of the node address. , It is possible to recognize whether the slave 20 that has issued the response is connected under which repeater, or the like. The repeater 30 is also assigned a node address, and the personal computer 42 must also make a status read request to each repeater 30 to know which node address of the repeater 30 is present on the network. Can be.
[0041]
The above-described series of processing is performed in steps (6) to (9) in FIG. Note that the example shown in FIG. 7 shows a standard example. If the repeater 30 does not exist up to the master unit 12, step (6) is omitted, and a plurality of repeaters exist. If so, the process of step (6) is executed a plurality of times.
[0042]
FIGS. 6 and 7 show a standard one on the assumption that there is a target slave. However, usually, there is almost no slave at every node address, and an empty number is set. There is also a node address. In this case, since no response is returned, naturally, in the example of FIG. 7, the process ends with a timeout until the process (3) or (4). In this case, since there is no response in step 6 in FIG. 6, it is recognized that there is no slave having the node address on the network, and the process returns to step 1 to check the next node.
[0043]
As a specific example, as shown in FIG. 8, when the master transmits a status read command (EVE_frame) to the slave # 30, the slave # 30 that has received the status read command immediately returns a response frame (▲). 1 ▼). Then, while the EVE_frame is being repeated for the master, the repeater # 5 writes the node address of its own station in the response. As a result, since the data changes, the CRC (sum check) is recalculated, and the updated response (of course, waveform shaping) is output to the master unit after recalculation ((2)).
[0044]
Similarly, the updated response (including: the node address of the repeater # 5) is taken into the repeater # 15, so that the same processing as that of the above-described repeater # 5 is performed, and the node address of the repeater # 5 is obtained. After that, a response (CRC is also updated) in which the node address of the repeater # 15 is added is generated and output to the master unit 12 ((3)).
[0045]
Therefore, in the master unit 12 (personal computer 42) receiving the response, since the repeaters # 5 and # 15 are written in the data area of the EVE_frame, the two repeaters between the slave # 30 and the repeater # 15 → It can be recognized that the connection is made in the order of # 5 → slave.
[0046]
In the status data in the response to the status read request, addresses of three repeaters can be sequentially stored as shown in FIG. 9, for example. Then, each repeater adds its own address to a predetermined storage area of the status information. Specifically, if the address information of the repeater is not stored in the obtained response, the own address is stored in the storage area of the address information of the first repeater. If the node address of another repeater is already stored in the storage area of the address information of the first repeater and the node address is not stored in the storage area of the node address information of the second repeater, the second repeater is used. Stores its own node address in the node address of. Similarly, if the node address of another repeater is already stored in the address information area of the first and second repeaters, and the node address is not stored in the storage area of the node address information of the third repeater, 3 The node address of the repeater is stored in the node address of the repeater. Whether or not a node address is stored in the storage area of each node address information can be easily determined by, for example, providing a flag indicating whether or not the node address has been stored or a flag indicating a next storage area. Of course, the additional form of the node address is not limited to the illustrated one, and various forms can be applied.
[0047]
Then, by repeatedly executing the above-described processing for each slave, for example, a network configuration diagram as shown in FIG. 10 can be created, and such a configuration diagram can be displayed on the monitor screen of the display device 42a. As is clear from FIG. 10, since it is possible to know under which repeater the slave is located on the network, a configuration diagram close to the actual network wiring can be displayed on the personal computer 42.
[0048]
【The invention's effect】
As described above, according to the present invention, in a network system including a repeater, a slave connected downstream of the repeater can easily recognize which repeater is located downstream. Moreover, since the repeater itself can perform such processing without holding the slave information connected downstream, the configuration of the repeater can be simplified and inexpensive.
[Brief description of the drawings]
FIG. 1 is a diagram showing an example of a conventional monitor screen.
FIG. 2 is a diagram illustrating an example of a network system configuration according to an embodiment of the present invention.
FIG. 3 is a diagram illustrating an example of an internal configuration of a master unit.
FIG. 4 is a diagram illustrating an example of an internal configuration of a slave.
FIG. 5 is a diagram showing an example of the internal configuration of a repeater.
FIG. 6 is a flowchart illustrating the operation of the entire network system for implementing the monitoring method.
FIG. 7 is a time chart for explaining the operation of the entire network system for implementing the monitoring method.
FIG. 8 is a diagram illustrating the function of a repeater.
FIG. 9 is a diagram illustrating information on a node address of a repeater in a data structure of a response.
FIG. 10 is a diagram showing an example of a monitor screen displayed by performing the monitoring method of the present invention.
[Explanation of symbols]
10 PLC
11 CPU unit
12 Master unit
12a Communication interface
12b Master ASIC
12c RAM
12d MPU
12e EEPROM
12f LED display
12g setting switch
12h interface
20 slaves
20a Communication interface
ASIC for 20b slave
20d MPU
20e EEPROM
20f LED display
20g setting switch
20h interface
20i power supply
20j I / O section
30 repeaters
31, 32 Communication interface
ASIC for 33 repeaters
34 Power supply section
35 LED display
36 Setting switch
40 Fieldbus
40a Field bus
41 Terminating resistor
42 PC
42a display device

Claims (5)

A monitoring method in a network system including a configuration in which at least one repeater intervenes between a master and a slave,
The master issues a status read command to the slave,
The slave receiving the status read command returns a response to the master,
When relaying the response, the repeater adds identification information identifying itself to the response,
The network system characterized in that the device that has obtained the response monitors the network configuration information by recognizing the connection relationship between the slave and the repeater based on the presence or absence of the specific information stored in the response and the content thereof. Monitor method. A monitoring system in a network system including a configuration in which at least one repeater intervenes between a master and a slave,
The master has a function of issuing a status read command to the slave,
The slave has a function of returning a response to the master when receiving the status read command addressed to itself,
The repeater has a function of adding identification information identifying itself to the response when relaying the response,
The device that has obtained the response has a function of recognizing the connection relationship between the slave and the repeater from the presence or absence and the content of the specific information stored in the response, and outputting network configuration information to an output unit. A monitoring system characterized by the following. The master constitutes a programmable controller,
The monitoring system according to claim 2, wherein the device is a monitor device connected to the program controller. A repeater mounted between a master and a slave configuring a network system, and relaying data transmitted between the master and the slave,
When the slave that has received the status read command issued from the master relays a response returned to the master, the slave has a function of adding identification information identifying itself to the response. Characteristic repeater. A relay including a configuration in which at least one repeater intervenes between a master and a slave, wherein the repeater receives a status read command issued from the master, and relays a response returned to the master. A monitoring device for monitoring configuration information of a network system having a function of adding identification information identifying itself to the response,
A function of acquiring the response returned by the slave and analyzing the content thereof;
From the presence or absence of the specific information stored in the response, it is determined whether or not the slave is connected under a predetermined repeater, and from the content of the specific information, the slave is connected under any repeater. A function of recognizing the connection relationship between the slave and the repeater by determining whether
A monitor device having a function of outputting network configuration information obtained based on the recognized connection relationship to an output unit.

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