JP7613110B2 - CONTROLLER, SETTING DEVICE, CONTROL METHOD, AND PROGRAM - Google Patents

Description

The present invention relates to a controller, a setting device, a control method, and a program for setting the propagation delay time of a signal in a field network.

In the field of factory automation (FA), various types of devices that share work processes are controlled. In order to operate various controllers, remote I/O, and manufacturing devices used in work in a certain area such as a factory facility in a coordinated manner, an industrial network, also called a field network, that connects these devices has been constructed.
In a field network, the devices that make up the system are connected by cables. A propagation delay occurs in the signals transmitted between the devices, which is roughly proportional to the length of the cables. Meanwhile, among the processes that each device must execute, there are fixed-period tasks that must be completed within a given control period.

JP 2013-137251 A JP 2018-19454 A JP 2017-102900 A Japanese Patent Application Publication No. 8-202759

Conventionally, a generous cable length (e.g., 1000 meters) was assumed as a default, and control was performed so that periodic tasks were completed within a control period, taking into consideration the propagation delay time corresponding to the assumed cable length. This resulted in the propagation delay time being set longer than necessary, which put a strain on the time available for actual processing of periodic tasks within a control period. To solve this problem, users would manually set the propagation delay time based on the length of the cable actually being used. However, this was time-consuming for users, and it was also difficult to set the propagation delay time to an accurate value.
Although the above-mentioned patent documents disclose techniques for measuring cable length, they do not disclose any consideration of propagation delay time.

In view of the above, the present invention aims to provide a technology that allows users to set an appropriate propagation delay time accurately in a field network without any effort on their part.

In order to solve the above problems, a controller according to one embodiment of the present invention is a controller connected to a field network that connects multiple slave devices with cables, and includes an SQI value acquisition unit that acquires an SQI (signal quality indicator) value measured in the physical layer communication circuit of each slave device, a total cable length calculation unit that calculates the cable length between each slave device based on the SQI value acquired by the SQI value acquisition unit and calculates the total cable length in the field network, and a propagation delay time setting unit that sets the propagation delay time of a signal in the field network based on the total cable length.

According to the above configuration, the total cable length can be calculated accurately without any effort on the part of the user, and the signal propagation delay time can be calculated accurately from the calculated total cable length. This makes it possible to set an appropriate propagation delay time, and as a result, it is possible to increase the time that can be used for the actual processing of periodic tasks within a control period.

The controller according to the above aspect may further include a scheduling unit that instructs the SQI value acquisition unit to perform the SQI value acquisition process, the total cable length calculation unit to perform the total cable length calculation process, and the propagation delay time setting unit to perform the propagation delay time setting process at a predetermined timing.

With the above configuration, the controller sets the propagation delay time at a predetermined timing even without a trigger, so the propagation delay time can be set at an appropriate timing without placing a burden on the user.

The controller according to the above aspect may further include an execution instruction unit that instructs the SQI value acquisition unit to execute the SQI value acquisition process, the total cable length calculation unit to execute the total cable length calculation process, and the propagation delay time setting unit to execute the propagation delay time setting process in response to an instruction input from outside.

With the above configuration, the user can reset the propagation delay time when necessary, such as when starting up the system or replacing a cable.

In addition, in the controller according to the above aspect, the SQI value acquisition unit may acquire the SQI value from each of the slave devices multiple times, and the total cable length calculation unit may calculate the cable length between each of the slave devices based on the average value of the SQI values acquired multiple times.

According to the above configuration, the SQI value may temporarily become large due to the influence of noise, etc., but as described above, by calculating the cable length based on the average value of values obtained multiple times, the propagation delay time can be set more accurately.

To solve the above problem, a setting device according to one aspect of the present invention may be a setting device that is communicatively connected to a controller, and may include an execution instruction sending unit that sends instructions to the execution instruction unit in response to an instruction from a user to execute an SQI value acquisition process in the SQI value acquisition unit, a total cable length calculation process in the total cable length calculation unit, and a propagation delay time setting process in the propagation delay time setting unit.

With the above configuration, the user can reset the propagation delay time when necessary, such as when starting up the system or replacing a cable.

The setting device according to the above aspect may further include a setting information transmission unit that acquires the propagation delay time set by the propagation delay time setting unit and transmits the propagation delay time to the controller together with setting information for the controller.

With the above configuration, the user can send the propagation delay time to the controller along with the controller's configuration information.

In order to solve the above problems, a control method according to one aspect of the present invention is a control method for a controller connected to a field network that connects multiple slave devices with cables, and includes an SQI value acquisition step of acquiring an SQI (signal quality indicator) value measured in a physical layer communication circuit of each of the slave devices, a total cable length calculation step of calculating the cable length between each of the slave devices based on the SQI value acquired by the SQI value acquisition step and calculating the total cable length in the field network, and a propagation delay time setting step of setting a propagation delay time of a signal in the field network based on the total cable length.

The above configuration can achieve the same effect as the above controller.

In order to solve the above problem, a controller program according to one aspect of the present invention may be a controller program for causing a computer to function as the controller, and may be a program for causing a computer to function as each of the above parts.
According to the above configuration, it is possible to achieve the same effects as the above controller.

To solve the above problems, a control program according to one aspect of the present invention may be a configuration program for causing a computer to function, and may be a configuration program for causing a computer to function as each of the above parts.

The above configuration can achieve the same effect as the setting device.

According to one aspect of the present invention, in a field network, the total cable length can be accurately calculated without any effort on the part of the user, and an appropriate propagation delay time can be set from the total cable length. As a result, the time during which a user's program can be executed within a control period can be increased.

1 is a diagram showing a configuration of a group of devices belonging to a field network to which a controller according to an embodiment of the present invention is connected; 2 is a block diagram showing a functional configuration of a controller and an installation device included in FIG. 1 . 2 is a graph showing the relationship between the SQI value and the cable length in the slave device included in FIG. 1 . 5 is a flowchart showing a flow of a propagation delay time setting process executed in the controller and the setting device according to the embodiment of the present invention. FIG. 2 is a diagram showing an example of a setting screen in the setting device included in FIG. 1 .

Below, an embodiment of the present invention will be described with reference to the drawings.

§1 Application example <System configuration>
1 is a configuration diagram showing a system 100 including a controller according to this embodiment and connected via a field network. The configuration of the system 100 will be described below with reference to FIG.

As shown in FIG. 1, the system 100 includes a plurality of devices connected by a field network. More specifically, the system 100 includes a controller (e.g., a programmable logic controller (PLC)) 101, a plurality of slave devices 102a-102f, a setting device 105, an HMI (Human Machine Interface) 104, and a hub device 103. The plurality of slave devices 102a-102f are collectively referred to as slave devices 102. The controller 101 and the plurality of slave devices 102a-102f are connected by a communication network such as EtherNET (registered trademark)/IP or EtherCAT (registered trademark) via the hub device 103, and work together to realize factory automation (FA). Note that the type of communication network is not limited to the above.

The controller 101 controls the operations of a plurality of slave devices 102a to 102f included in the entire system 100. The HMI 104 is an interface that displays the operating state of the controller 101 and accepts various operational instructions given to the controller 101 by a user.
The setting device 105 is configured with a notebook PC or the like, and is connected to the controller 101 via a USB (Universal Serial Bus). The setting device 105 stores configuration information of the system 100, and sets various setting information and programs used for control in the controller 101 in response to user instructions.

Some of the programs executed by the devices included in the system 100 need to be executed at a certain control period. On the other hand, signals transmitted and received through cables between the devices will have a propagation delay depending on the length of the cable. Therefore, it is necessary to control the timing so that the execution of the program is completed within the time obtained by subtracting the propagation delay time from the control period. In this embodiment, the controller 101 calculates the cable length connecting each device from the SQI value measured by each slave device 102a to 102f. Next, the controller 101 calculates the total cable length of the entire system 100 by adding up these cable lengths based on the configuration information of the system 100, and accurately calculates the propagation delay time from the total cable length. The controller 101 schedules control so that each device operates within the control period based on the calculated propagation delay time.

§2 Configuration Example The functional configuration of the controller 101 and the setting device 105 will be described below with reference to FIG.

<Functional configuration of controller and setting device>
Fig. 2 is a block diagram showing the functional configuration of the controller 101 and the setting device 105. As shown in Fig. 2, the controller 101 includes an SQI value acquisition unit 1011, a total cable length calculation unit 1012, a propagation delay time setting unit 1013, a scheduling unit 1014, and an execution instruction unit 1015. The SQI value acquisition unit 1011, the total cable length calculation unit 1012, and the propagation delay time setting unit 1013 are also collectively referred to as an execution unit 1010.

The execution unit 1010 of the controller 101 performs the process of setting the propagation delay time. The scheduling unit 1014 and the execution instruction unit 1015 instruct the execution unit 1010 when to start the process of setting the propagation delay time. Note that it is sufficient for the controller 101 to include at least one of the scheduling unit 1014 and the execution instruction unit 1015.

The SQI value acquisition unit 1011 acquires an SQI (signal quality indicator) value measured in the physical layer communication circuit of each slave device 102. The total cable length calculation unit 1012 calculates the cable length between each slave device 102 based on the SQI value acquired by the SQI value acquisition unit 1011, and calculates the total cable length in the field network. The propagation delay time setting unit 1013 sets the propagation delay time of signals in the field network based on the total cable length. The controller 101 controls the operation timing of each device within a control period based on the set propagation delay time.

The scheduling unit 1014 instructs the SQI value acquisition unit 1011 to perform the SQI value acquisition process, the total cable length calculation unit 1012 to perform the total cable length calculation process, and the propagation delay time setting unit 1013 to perform the propagation delay time setting process at a predetermined timing. For example, the scheduling unit 1014 may instruct the execution unit 1010 to start the above propagation delay time setting process at a certain cycle (for example, at a fixed time every day, every specified number of days, a specified date and time every month, etc.). Alternatively, the scheduling unit 1014 may detect the start-up of the controller 101, the replacement of the cable, etc., and instruct the execution unit 1010 to start the above propagation delay time setting process at that timing. That is, the controller 101 automatically performs the calculation of the total cable length and the propagation delay time setting process at a set timing even without an external trigger. According to the above configuration, even if the cable is replaced or the configuration of the system 100 is changed, the optimal propagation delay time for that configuration can be automatically set. It can also deal with deterioration of the cable over time.

Alternatively, the execution instruction unit 1015 may instruct the SQI value acquisition unit 1011 to execute the SQI value acquisition process, the total cable length calculation unit 1012 to execute the total cable length calculation process, and the propagation delay time setting unit 1013 to execute the propagation delay time setting process in response to an instruction input from outside. For example, the user may send a predetermined message from the setting device 105 to instruct the controller 101 to start the propagation delay time setting process. The execution unit 1010 of the controller 101 may start the propagation delay time setting process using the reception of the message as a trigger.

When the user sends a trigger to start processing to the controller 101, for example, when starting up the system 100 or replacing a cable, the user may use the setting device 105 to send a specific message to the controller 101, and the controller 101 may use this as a trigger to start executing the propagation delay time calculation process.

The setting device 105 may include an execution instruction sending unit 1051 that sends instructions to the execution instruction unit 1015 of the controller 101 to execute the SQI value acquisition process in the SQI value acquisition unit 1011 of the controller 101, the total cable length calculation process in the total cable length calculation unit 1012, and the propagation delay time setting process in the propagation delay time setting unit 1013 in response to an instruction from the user. As described above, the execution unit 1010 of the controller 101 may start the propagation delay time setting process using an instruction from the user as a trigger. With the above configuration, the user can instruct the controller 101 to execute the propagation delay time setting process when necessary, such as when replacing a cable.

The setting device 105 may further include a setting information transmission unit 1052 that acquires the propagation delay time set by the propagation delay time setting unit 1013 of the controller 101 and transmits the propagation delay time to the controller 101 together with various setting information for the controller 101. The controller 101 executes control of each device based on the acquired propagation delay time and setting information.

The following describes in order the calculation of the SQI value, the calculation of the cable length, the calculation of the total cable length, and the setting of the propagation delay time performed by the execution unit 1010 of the controller 101.

<Calculation of SQI value>
The SQI value acquisition unit 1011 of the controller 101 acquires the SQI value. The SQI value is measured in the physical layer communication circuit of the slave device 102. The SQI value may be measured in the physical layer communication circuit of the controller 101. Each slave device 102 stores the measurement result of the SQI (signal quality indicator) value in the signal communication between the device directly connected by the cable. The SQI value is a numerical value indicating the signal quality, and is calculated from the ratio of noise to normal signals. The SQI value can be measured at all times without stopping the communication between the devices. Here, it is sufficient to provide the physical layer communication circuit of one of the two devices connected by the cable with the function of measuring the SQI value. However, it is more preferable to provide this function to the controller 101 connected to more devices.

<Calculating cable length>
The total cable extension calculation unit 1012 of the controller 101 calculates the cable length between each slave device 102 based on the SQI value acquired by the SQI value acquisition unit 1011. The SQI value is related to the cable length. A data sheet stored in the PHY communication circuit of each device stores a table showing the relationship between the SQI value and the cable length for a standard cable. For example, the data sheet table shows the relationship that an SQI value of 2.0 to 2.5 corresponds to a cable length of 50 m, and an SQI value of 3.0 to 3.5 corresponds to a cable length of 100 m. The total cable extension calculation unit 1012 of the controller 101 receives the SQI value from each device and calculates the cable length.

The longer the cable length, the higher the SQI value increases almost linearly. The SQI value acquisition unit 1011 may acquire the SQI value from each slave device 102 multiple times, and the total cable length calculation unit may calculate the cable length between each slave device 102 based on the average value of the SQI values acquired multiple times. Since the SQI value varies due to the influence of noise during measurement, it is possible to improve accuracy when calculating the cable length by averaging tens of thousands of SQI value data.

Furthermore, when the cable total length calculation unit 1012 calculates the cable length from the SQI value, a graph showing the relationship between the SQI value and the cable length may be used. Fig. 3 shows an example. In the graph of Fig. 3, the horizontal axis represents the cable length, and the vertical axis represents the SQI value. It can be seen from Fig. 3 that the SQI value increases almost linearly as the cable length increases. The following formula may be derived in advance by performing a regression analysis on the relationship between the cable length and the SQI value based on the actual measured values of a cable of a specified standard.
Cable length = (SQI value - a) / b
In the above conversion formula, the values of a and b vary depending on the type of cable. For a cable of a standard specification, a = 1.1216 and b = 0.0109, respectively. When a cable of a non-standard specification is used, the above conversion formula may be calculated in advance for each type of cable in order to set a more accurate propagation delay time.

The total cable length calculation unit 1012 of the controller 101 calculates the total cable length in the field network. That is, the controller 101 acquires the SQI value from each slave device 102, calculates the length of each cable based on the above table, graph, or conversion formula, and calculates the total cable length by adding up these cable lengths.

<Calculation of propagation delay time>
The propagation delay time setting unit 1013 of the controller 101 sets a propagation delay time of a signal in the field network based on the calculated total cable length. The propagation delay time increases approximately in proportion to the total cable length.

In the setting device 105, as an example, the propagation delay time is set by default with the total cable length set to 1000 m. If the setting is changed using a value calculated based on the measurement results from the above SQI value, an appropriate propagation delay time can be set.

<Explanation of processing flow>
4 is a flowchart showing a process flow for setting a propagation delay time in an embodiment of the present invention. The process flow for setting a propagation delay time will be described below with reference to FIG.

(Step S110)
First, the total cable length calculation unit 1012 of the controller 101 sets (calculates) the total cable length in the field network. If the user manually instructs the start of the total cable length calculation process, the process proceeds to step S120, and if the controller 101 automatically starts the total cable length calculation process, the process proceeds to step S220.
Steps S120 to S170 below show the flow when the user manually instructs the start of the above process.

(Step S120)
An instruction from the user to execute the above process is transmitted from the execution instruction transmission unit 1051 of the setting device 105 to the execution instruction unit 1015 of the controller 101. For example, the user may transmit a predetermined message from the execution instruction transmission unit 1051 of the setting device 105 to the execution instruction unit 1015 of the controller 101. The execution instruction unit 1015 of the controller 101 uses this as a trigger to issue an instruction to start the propagation delay time setting process.

(Step S130)
The execution instruction unit 1015 of the controller 101 issues an instruction to the execution unit 1010 (SQI value acquisition unit 1011) to measure the cable length (issues an instruction to measure the SQI value).

(Step S140)
The SQI value acquisition unit 1011 that receives the instruction acquires the SQI value measured by the function of the PHY communication circuit from each slave device 102. That is, each device returns the measured SQI value to the SQI value acquisition unit 1011 of the controller 101. As described above, since the SQI value varies, accuracy can be improved by averaging tens of thousands of pieces of data.

(Step S150)
The total cable length calculation unit 1012 of the controller 101 calculates the cable length based on the SQI value received from the SQI value acquisition unit 1011. The total cable length calculation unit 1012 further calculates the total cable length in the system 100 by adding up each cable length.

(Step S160)
The controller 101 transmits the calculated total cable length to the setting device 105. The setting device 105 stores the calculated total cable length in the [total cable length] field. Fig. 5 shows an example of a display/input screen of the setting device 105 for setting information for the controller 101. In this example, a default value of 1000m is set for the total cable length, but this value is rewritten to the total cable length value calculated by the controller 101.

(Step S170)
The setting device 105 transmits the set value of the total cable length to the controller 101 together with setting information for the controller 101 based on an instruction from a user. The propagation delay time setting unit 1013 of the controller 101 sets the propagation delay time of a signal in the field network based on the calculated total cable length. Note that in the controller 101, the calculation result of the total cable length by the total cable length calculation unit 1012 may be sent directly to the propagation delay time setting unit 1013 to set the propagation delay time.

When the user replaces a cable, modifies the system, or otherwise needs to do so, the setting device sends a triggering instruction in step S120, and the controller 101 (execution unit 1010) executes the processes from S130 to S170 to reset the propagation delay time.

Next, we will explain the process (steps S220 to S270) when the controller 101 automatically calculates the propagation delay time.

(Step S220)
The scheduling unit 1014 of the controller 101 instructs the execution unit 1010 of the controller 101 to execute at a predetermined timing. That is, the calculation process of the total cable length is executed (started) inside the controller 101. Unlike the case of the manual process (step S120) described above, the controller 101 starts the setting process without a trigger.

(Steps S230 to S250)
The processes from steps S230 to S250 are the same as those from steps S130 to S150 described above, and therefore will not be described repeatedly here.

(Step S260)
The propagation delay time setting unit 1013 of the controller 101 sets a propagation delay time based on the calculated total cable length. The controller 101 schedules control based on the set propagation delay time.

(Step S270)
According to the preset timer, the controller 101 returns to step S220 and repeats the series of propagation delay time setting processes.

With the above configuration, the propagation delay time can be reset to an appropriate value at a specified timing without the user having to send a trigger to the controller 101. The timing may be regular or irregular.

<Calibration>
The above describes an example of the propagation delay time setting process in a field network using a cable of a standard specification. However, the present invention is not limited to the above example, and can also be applied to a case where a propagation delay time is set in a field network using a cable of a non-standard specification. In this case, a more appropriate propagation delay time can be calculated by performing calibration according to the cable of the non-standard specification.

First, the SQI value is measured for cables of non-standard specifications, and the relationship between the measured SQI value and each cable length is obtained. Next, the relationship between the total cable length calculated from the cable length and the propagation delay time is confirmed by experiment. Regarding the relationship between the SQI value and cable length, a graph such as that shown in Figure 3 may be created, or a conversion formula or table showing the relationship between the SQI value and cable length may be created. As described above, the total cable length can be calculated from the SQI value, and an appropriate propagation delay time can be set from the total cable length.

[Software implementation example]
The control blocks of the controller 101 and the setting device 105 (particularly the SQI value acquisition unit 1011, the total cable length calculation unit 1012, the propagation delay time setting unit 1013, the scheduling unit 1014, the execution instruction unit 1015, the execution instruction transmission unit 1051, and the setting information transmission unit 1052) may be realized by a logic circuit (hardware) formed in an integrated circuit (IC chip) or the like, or may be realized by software.

In the latter case, the controller 101 and the setting device 105 are provided with a computer that executes the instructions of a program, which is software that realizes each function. This computer is provided with, for example, one or more processors, and a computer-readable recording medium that stores the program. The object of the present invention is achieved by the processor reading the program from the recording medium and executing it in the computer. The processor can be, for example, a CPU (Central Processing Unit). The recording medium can be a "non-transient tangible medium", such as a ROM (Read Only Memory), as well as a tape, a disk, a card, a semiconductor memory, a programmable logic circuit, etc. The computer may further include a RAM (Random Access Memory) that expands the program. The program may be supplied to the computer via any transmission medium (such as a communication network or a broadcast wave) that can transmit the program. Note that one aspect of the present invention can also be realized in the form of a data signal embedded in a carrier wave, in which the program is embodied by electronic transmission.

The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. The technical scope of the present invention also includes embodiments obtained by appropriately combining the technical means disclosed in different embodiments.

100 System 101 Controller 102 Slave device 103 Hub device 104 HMI
105 Setting device 1010 Execution unit 1011 SQI value acquisition unit 1012 Cable total extension calculation unit 1013 Propagation delay time setting unit 1014 Scheduling unit 1015 Execution instruction unit 1051 Execution instruction transmission unit 1052 Setting information transmission unit

Claims (9)

A controller connected to a field network that connects a plurality of slave devices with cables,
an SQI value acquisition unit that acquires an SQI (signal quality indicator) value measured in a physical layer communication circuit of each of the slave devices;
a total cable length calculation unit that calculates a cable length between each of the slave devices based on the SQI value acquired by the SQI value acquisition unit, and calculates a total cable length in the field network;
a propagation delay time setting unit that sets a propagation delay time of a signal in the field network based on the total cable length;
A controller comprising: The controller according to claim 1, further comprising a scheduling unit that instructs the SQI value acquisition unit to perform an SQI value acquisition process, the total cable length calculation unit to perform a total cable length calculation process, and the propagation delay time setting unit to perform a propagation delay time setting process at a predetermined timing. The controller according to claim 1 or 2, further comprising an execution instruction unit that instructs the SQI value acquisition unit to execute the SQI value acquisition process, the total cable length calculation unit to execute the total cable length calculation process, and the propagation delay time setting unit to execute the propagation delay time setting process in response to an instruction input from outside. The SQI value acquisition unit acquires the SQI value from each of the slave devices a plurality of times,
4. The controller according to claim 1, wherein the total cable length calculation unit calculates the cable length between each of the slave devices based on an average value of the SQI values obtained multiple times. A setting device communicatively connected to the controller according to claim 3,
A setting device comprising: an execution instruction transmission unit that transmits instructions to the execution instruction unit to execute an SQI value acquisition process in the SQI value acquisition unit, a total cable length calculation process in the total cable length calculation unit, and a propagation delay time setting process in the propagation delay time setting unit in response to an instruction from a user. The setting device according to claim 5, further comprising a setting information transmission unit that acquires the propagation delay time set by the propagation delay time setting unit and transmits the propagation delay time to the controller together with setting information for the controller. A method for controlling a controller connected to a field network that connects a plurality of slave devices with cables, comprising the steps of:
an SQI value acquisition step of acquiring an SQI (signal quality indicator) value measured in a physical layer communication circuit of each of the slave devices;
a total cable length calculation step of calculating a cable length between each of the slave devices based on the SQI value acquired in the SQI value acquisition step, and calculating a total cable length in the field network;
a propagation delay time setting step of setting a propagation delay time of a signal in the field network based on the total cable length;
A control method comprising: A controller program for causing a computer to function as the controller according to any one of claims 1 to 4, the controller program causing the computer to function as each of the above-mentioned units. A setting program for causing a computer to function as the setting device according to claim 5 or 6, the setting program causing the computer to function as each of the above-mentioned parts.

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